# 3D Muscle Lab — full text > The online course for learning the muscles of the human body The pages and articles listed in https://3dmusclelab.com/llms.txt, in the same order. --- Source: https://3dmusclelab.com/ For Pilates teachers, yoga teachers, massage therapists & trainers # Learn your muscles. Actually remember them. Most anatomy resources were written for medical students. This one wasn’t. **65 muscles taught in 3D, with a quiz at every stage.** Used inside teacher training programs in the US, Mexico, Germany, and Australia. ![3D model of the psoas contracting to raise the leg](https://3dmusclelab.com/wp-content/uploads/2026/09/psoas-clip.jpg) 65 muscles covered 79 lessons 15 hrs of video 30 day money-back guarantee Why anatomy doesn’t stick ## Flat diagrams. Dense text. Forgotten by Friday. You learned the muscles once. You could name them for an exam. Then a client walks in with a shoulder that doesn’t move the way it should, and the picture in your head is a page from a textbook rather than a body. That isn’t a memory problem. It’s a format problem. A flat illustration of a muscle tells you where it sits. It doesn’t show you what happens when it shortens, what it pulls on, or why the movement you’re watching looks the way it does. Anatomy sticks when you can see it move, hear it explained, and then be asked to recall it. That's what this course is built around. ## 65 muscles. Every one of them like this. ![Deltoid Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/deltoid-mus.jpeg) ![Trapezius Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/trapezius-mus.jpeg) ![Biceps Brachii](https://3dmusclelab.com/wp-content/uploads/2018/10/biceps-brachii-muscle.jpg) ![Gluteus Maximus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/gluteus-maximus-mus.jpeg) ![Iliopsoas Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/iliopsoas-mus.jpeg) ![Rectus Abdominis Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/rectus-abdominus-mus.jpeg) ![Gastrocnemius Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/gastrocnemius-mus.jpeg) ![Sternocleidomastoid Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/sternocleidomastoid-2-mus.jpeg) How each lesson works ## Four steps. One muscle. Locked in. 1. 01 **Bony landmarks** Before the video, you preview the attachment points on the skeleton. Try to recall where the muscle attaches before opening each toggle. That retrieval attempt is the first layer of memory work. 2. 02 **Watch the lecture** David walks through origin, insertion, action, and clinical relevance, with the 3D model on screen the whole time. Plain language. No jargon for its own sake. 3. 03 **Look, listen, read** Each muscle gets its own 3D image with audio narration. Look at the model, listen, and read at the same time. Three input channels at once. 4. 04 **Test yourself** Multiple quiz styles — recall, recognition, image-based — reinforce the material in different ways. This is what separates knowing a muscle from having read about one. That's the format for all 65 muscles. [Work through one free →](https://3dmusclelab.com/free-hamstring-lesson/) No signup, no card. ![David Keil, M.S. Exercise Physiology, LMT, NMT](https://3dmusclelab.com/wp-content/uploads/2018/07/david-keil-profile-800px.png) Who teaches it ## David Keil — M.S. Exercise Physiology, LMT, NMT Kinesiology was the first course I taught, back in 1999, at a massage school in Miami. I was handed a complex subject and a room full of students from every background, and I had to make it land. That’s been the work ever since — in the studio, in workshops around the world, and in *Functional Anatomy of Yoga*. Take something complicated and explain it so people actually keep it. This course is that method built in 3D, with the models I always wished I’d had in the classroom. From practitioners like you ## What happens when anatomy finally clicks. > "Before 3D Muscle Lab, I couldn’t make muscles, their attachments, and the related actions come alive in my mind’s eye. I could only find flat pictures with words, words, words. 3D Muscle Lab showed me the body moving and how the muscles are attached. It all comes alive and makes sense." > > Kate Harper Yoga teacher & anatomy student > "I used to have headaches just trying to learn the names and terminology. David’s instruction is so clear. Even for someone like me who speaks Spanish and not much English — I could understand the whole program. Learning anatomy couldn’t be easier." > > Paulina R. Pilates instructor, Spain Two ways in ## Which one are you? Learning it yourself ### You want the anatomy in your own head Full access to all 12 modules and 79 lessons. Every 3D model, every bony landmark, every audio card and quiz. Monthly, annual, or lifetime — and a 30-day money-back guarantee either way. [See pricing →](https://3dmusclelab.com/pricing/) Teaching it to trainees ### You run a teacher training program License the course for your students instead of building an anatomy module yourself. Pre-recorded, self-paced, quizzed at every stage — the format certifying bodies permit for anatomy. Programs in the US, Mexico, Germany, and Australia already run it. [See program licensing →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) Start here ## See one lesson before you decide anything. A complete hamstring lesson, free and ungated. No email, no card. Work through it the way your students would, and see whether the 3D models do what a textbook can’t. [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) Or [see everything that’s in the course](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) first. --- Source: https://3dmusclelab.com/about/ # About David Keil ![David Keil, anatomy educator and author of Functional Anatomy of Yoga](https://3dmusclelab.com/wp-content/uploads/2018/07/david-keil-profile-800px.png) ## This is about YOU learning your muscles. As far back as I can remember, I have enjoyed deconstructing and reconstructing things. Whether I was pulling apart a radio in our garage or building a bike out of various pieces, I love understanding how things work. From an educational perspective, I enjoy the challenge of taking complex topics and making them simple and understandable to everyone. This is the challenge that I've taken on for myself since 1999, when I taught [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) for the first time. The reward has been tremendous! Developing content on anatomy so that people not just understand it but also benefit from it, leaves me fulfilled. Because I know that when therapists, and teachers understand their anatomy, it helps them to help others. ## Functional Anatomy of Yoga This mission to make the complex simple is exactly what I did in my book, *Functional Anatomy of Yoga*. I took the complexity of anatomy and the complexity of yoga and brought them together in a conversational tone. Why? So that the people reading the book would understand it! ![Functional Anatomy of Yoga book cover](https://3dmusclelab.com/wp-content/uploads/2019/06/faoy-book-transparent-shadow.png) [![Yoganatomy.com logo](https://3dmusclelab.com/wp-content/uploads/2019/06/yoganatomy-logo.jpg)](https://www.yoganatomy.com) ## Yoganatomy.com - Where I sharpened my skills Since 2000, teaching anatomy in the yoga world has been my passion and it has literally taken me around the world. I started practicing yoga and Tai Chi back in 1988 when I was still in High School. That was years before yoga became popular and learning resources were extremely limited. While teaching kinesiology at Educating Hands, I realized that yoga teachers also needed to learn their anatomy in order to work with their students. I created yoganatomy.com and mixed my passion for yoga and anatomy. It's been a very fulfilling journey. ## More about David ![David Keil](https://3dmusclelab.com/wp-content/uploads/2026/09/david-keil-headshot.jpg) David Keil - M.S. Exercise Physiology - LMT, NMT - E-RYT 500 · YACEP - Authorized Level 2, Ashtanga Yoga 1. 1988 Yoga and Tai Chi, at 17 2. 1999 Teaching Kinesiology, Miami 3. 2001 Meets John Scott 4. 2002 First trip to Mysore 5. 2004 Authorized, Ashtanga Yoga David Keil was introduced to yoga in 1988 by his Tai Chi Chuan teacher. Both the Tai Chi and Yoga practice at the ripe age of 17 began his research into his own mind-body connections. His search continued through massage therapy where he discovered many insights and affirmations of what he had been exploring and finding on his own through his practices. One of the most important elements was the specific understanding of the musculoskeletal system and how fascinating, beautiful, and amazing the body is on the scientific level and how that directly played into and off of his own understanding of the human body. He was given names and explanations for some of the things he had been experiencing and feeling. As an instructor of Kinesiology (the study of movement and musculoskeletal anatomy) at Miami’s Educating Hands School of Massage from 1999–2003, David developed a fun, informal and informative style of teaching. By repeatedly teaching incoming students who had no prior understanding of anatomy, David was confronted with the problem of making such a complex and beautiful system accessible and understandable to the average person. David brings his unique style and ability to make things simple to the yoga world. Because of his passion and desire to share the human body with everyone, he delivers this complex and sometimes frustrating topic in a way that is very accessible and understandable to yoga practitioners. Over the years David has used his skills as a Neuromuscular Therapist to help people reduce their chronic pain patterns. He often brings this information into his workshops where students are regularly uncovering painful patterns or injuries in their bodies. --- Source: https://3dmusclelab.com/anatomy-for-pilates-teacher-training/ For Pilates Teacher Training Programs # The Anatomy Module for Your Pilates Teacher Training 65 muscles. 79 lessons. 3D video, built-in quizzes — self-paced, foundational kinesiology, muscles, where they attach, what they do. Technique stays with you. Assign the foundation, and spend your hours on the method that makes your program unique. [Start a 30-Day Trial](https://my.3dmusclelab.com/join/trial/) [Try a free hamstring lesson](https://3dmusclelab.com/free-hamstring-lesson/) ![Pilates teacher training students studying functional anatomy](https://3dmusclelab.com/wp-content/uploads/2025/03/pilates-teacher-training.jpg) 65 muscles covered 79 lessons 12 mo student access 1999 teaching anatomy since ## Anatomy is required. It’s also the hardest part of your program to staff. What it costs you now Every cohort, the same problem comes back around. Somebody has to teach anatomy, and that somebody is usually you. - **Prep time you don’t have.** Building and refreshing anatomy lectures runs 20–30 hours a cohort. - **A subject outside most teachers’ depth.** Excellent Pilates teachers aren’t necessarily confident teaching origins, insertions, and actions — and students can tell. - **Inconsistency between cohorts.** What gets covered depends on who taught it and how much time was left. - **Assessment you have to build yourself.** Writing and grading anatomy quizzes is its own project. - **Scheduling.** Bringing in an outside anatomy instructor means paying $1,500–3,000 and bending your calendar around their availability. What changes You assign a module. Your students work through it on their own time and arrive sharing the vocabulary. You teach your method. - **Zero prep.** It’s built, tested, and running in programs now. - **Consistent every cohort.** Same content, same language, same standard — every time. - **Assessment included.** Quizzes are part of the course. - **No calendar impact.** Self-paced. Students start when they enroll. - **$80 per student.** Roughly 1–2% of what they’re already paying you in tuition. Where it stops The course covers foundational kinesiology and nothing past it. No technique, no cueing, no repertoire, no application. Those are yours, and every teacher explains them differently. Students arrive knowing what the muscles are and what they do, so your teaching time goes to the part only you can teach. Built for how anatomy is actually allowed to be taught ## Anatomy is the part of your curriculum you’re meant to be able to hand off Whichever body your program answers to, the pattern is the same: repertoire, apparatus work, and special populations need a live component. **Anatomy doesn’t.** It’s the one block that can be delivered as structured, self-paced content — as long as it’s properly assessed. **The clearest example is [NPCP](https://3dmusclelab.com/npcp-anatomy-requirements-2027/), and it has a date on it.** Their updated eligibility requirements take effect on **January 1, 2027**. Under them, Pilates Repertoire and Special Populations must have an in-person or live virtual component, while **History of Pilates and Anatomy may be pre-recorded — provided a quiz supports the learning outcome.** The decision is closer than the date suggests. A comprehensive program runs 9 to 18 months, so any cohort you enroll now will graduate under the new standards. The curriculum needs to be settled before they start, not before January. **This course is built to exactly that specification: pre-recorded, self-paced, and quizzed at every stage.** Lesson quizzes are part of the course, so the assessment requirement is satisfied without you writing a single question. **There's a reason the standards draw the line where they do.** Foundational anatomy is identical in every program, so it can be standardized, recorded and tested. Technique can't be, which is why it still needs a live component. This course sits entirely on the side that's meant to be handed off. **And it travels.** Whether your program is working toward NPCP eligibility in the US, [PMA-ITTAP accreditation](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/) internationally, PAA recognition in Australasia, or registration through EuropeActive or CIMSPA, the anatomy content is the same body of knowledge — origins, insertions, actions, and how muscles produce and control movement. You can see [the full module and lesson breakdown here](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/#modules) to map against whichever standard you're working to. **One more thing standards bodies are asking for: verification.** Programs are increasingly required to verify and document what a candidate actually completed. Because quiz and test results are recorded per student, you have that documentation ready if you’re audited. See how it maps to your curriculum → Requirements vary by certifying and accrediting body and change over time. Always confirm current standards with your own organization. For reference: [NPCP Comprehensive requirements](https://nationalpilatescertificationprogram.org/NPCP/NPCP/Get_Certified/Requirements.aspx) · [NPCP Mat requirements](https://nationalpilatescertificationprogram.org/NPCPMAT/NPCPMAT/Get_Certified/Requirements.aspx) · [PMA ITTAP standards](https://www.pilatesmethodalliance.org/international-teacher-trainer-accreditation-for-pilates) ## How the course is built 1. 01 **Foundations** Musculoskeletal system, planes of movement, anatomical terminology, muscle contraction types. Everyone starts on the same page regardless of background. 2. 02 **Joint by joint** Each area of the body introduced as a whole, then broken into its bony landmarks — so muscles attach to something students can already picture. 3. 03 **Muscles** 65 muscles. Origin, insertion, and action, shown on rotating 3D models rather than a flat textbook plate. Video, written reference, and review tools in every lesson. 4. 04 **Tested** Lesson quizzes using 3D images. Students prove they retained it, and you don’t have to write a single question. ## How it fits into a program you’ve already built You don’t have to restructure anything. The course is modular, and directors run it three different ways. ### Flexible sequencing - Align modules with your repertoire blocks — shoulder module alongside shoulder work, hip module alongside turnout. - Assign lessons as stand-alone pre-work before in-person weekends. - Teach in the order provided, or rearrange to match your existing syllabus. Every module is plug-and-play. ### Three ways directors use it - **Pre-work for trainees.** Assign lessons ahead of contact hours so students arrive prepared. Recovers classroom time you’re currently spending on foundations. - **Faculty reference.** Standardize anatomical terminology across your teaching team — everyone using the same words for the same structures. - **Assessment.** Built-in quizzes work as baseline checks going in, or as a supplement to your own testing. ### Getting your students in 1. 1 **Start a free 30-day trial.** Full access, no card. Look at it properly before you commit anyone. 2. 2 **Register your students.** One form, used as many times as you need — register one student or a whole cohort. Each gets their own login and starts immediately. 3. 3 **Track completion.** Every quiz grade and every certificate is recorded, and you can download the full record for all your students at any time, so you can confirm the anatomy component is done before you certify. **Want the video inside your own LMS?** We can license it for embedding under a program agreement, whatever your size. That path includes quarterly enrollment reporting. If you’d rather not build anything, hosted access is less work for you and there’s nothing to maintain. ## Who’s teaching it ![David Keil, anatomy educator and author of Functional Anatomy of Yoga](https://3dmusclelab.com/wp-content/uploads/2018/07/david-keil-profile-800px.png) **David Keil**M.S. Exercise Physiology, LMT, NMT - Teaching kinesiology since 1999 - Author, *Functional Anatomy of Yoga* - Thousands of Pilates teacher trainees have completed this course - Programs running this course in the US, Mexico, Germany, and Australia Kinesiology was the first course I taught, back in 1999, at a massage school in Miami. The challenge then is the same one you’re facing now: take a genuinely complex subject and make it land for students from every possible background — dancers, athletes, career changers, people who haven’t opened a science textbook in twenty years. I’ve spent the years since teaching functional anatomy to movement professionals around the world, and writing *Functional Anatomy of Yoga* to do the same thing in print: take the complexity out without dumbing the content down. This course is that approach, built for Pilates teacher trainings that need anatomy handled properly and don’t have the faculty hours to build it from scratch. > “Students don’t struggle with anatomy because it’s hard. They struggle because nobody showed them what it looks like.” ## Simple per-student pricing ## Per Student $80 per student · 12 months access - Register students one at a time or a full cohort - No minimum, no contract, no commitment - Full course, all 79 lessons, all quizzes - Best for programs enrolling fewer than 15 students a year - Refund or exchange any student within 30 days [Register students](https://my.3dmusclelab.com/join/trial/) You'll start with a free 30-day trial, then register your students from your dashboard. ## Program Agreement Tiered pricing volume discounts start at 15 students - Your per-student rate drops at each enrollment tier - From $76 per student at 15 down to $52 at 201+ - Option to embed the video in your own LMS - Annual agreement, reconciled against actual enrollment - Best for programs running 15+ students a year [Talk to David →](mailto:admin@3dmusclelab.com?subject=Program%20Agreement%20Inquiry) Not sure yet? [**Try the full course free for 30 days**](https://my.3dmusclelab.com/join/trial/) and see how it fits your next training. No card required. ## Is this the right fit for your program? - I want to stop spending faculty hours on lecture-style anatomy - I want consistent anatomy language across every cohort and every teacher - I want faculty hours going to method and technique, not to naming muscles - I want 3D visuals and animation that go beyond what I can do in a classroom - I want assessments built in, with no prep on my end - I want something modular I can map to my existing syllabus - I want my students to keep the reference after they certify If three or more sound like you, this fits. ## Questions directors ask ### Does this satisfy my certifying body’s anatomy requirement? Requirements vary by organization and you should confirm against your own. The general pattern across bodies is that repertoire and special populations need a live component while anatomy can be delivered as structured self-paced content with proper assessment. NPCP is the clearest documented case: their updated standards, effective January 1, 2027, allow History of Pilates and Anatomy to be pre-recorded provided a quiz supports the learning outcome. This course is pre-recorded and quizzed at every stage. [The full module and lesson breakdown is here](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/#modules) if you want to review it against your standards. To be clear, we’re a curriculum provider, not an accrediting body. ### I’m outside the US — does this still work for my program? Yes. The anatomy is the same wherever you teach: origins, insertions, actions, and how muscles produce and control movement. Programs use this course in the US, Mexico, Germany, and Australia. Whether you’re working toward PMA-ITTAP accreditation, PAA recognition in Australasia, EuropeActive or CIMSPA registration, or NPCP eligibility for your graduates, send us your standard and we’ll map the curriculum against it. Course content is in English. ### What changes on January 1, 2027? NPCP’s updated eligibility requirements take effect then. Repertoire and Special Populations will need an in-person or live virtual component, while History of Pilates and Anatomy can remain pre-recorded with a supporting quiz. Graduates of programs that don’t meet the new standards get a six-month grace period from the effective date to apply. If you’re auditing your curriculum against the new rules, anatomy is the piece you’re permitted to hand off. Worth noting the timing: a cohort you enroll today will graduate under the new standards, so the decision is a now decision, not a 2027 one. ### How do I document that my students completed the anatomy component? Every trainee’s work is recorded: each lesson they complete and every quiz grade. Your teacher dashboard shows it at a glance, and you can download the full record as a spreadsheet at any time: progress, the grade on every quiz, and their certificate. Trainees who complete every lesson and score 75% or better on each quiz earn a certificate of completion with a unique code that anyone, including an auditor, can verify online. ### What does one student seat include? Everything: all 12 modules and 79 lessons, every quiz, the flip cards and drills, and a certificate on completion, for 12 months from the day the student joins. As lead teacher, your own access doesn’t expire. ### How long does it take a student to complete? Most students work through it over several weeks alongside the rest of your program. It’s self-paced, and access runs a full 12 months, so it doesn’t force a schedule on anyone. ### Do my students need any prior anatomy background? No. The course starts with fundamentals — terminology, planes of movement, how muscles work — before covering a single named muscle. ### How long do my students have access? 12 months from registration. That covers a comprehensive program running 9 to 18 months part-time, so students keep access through the whole of your training and for a while after. ### Is this Pilates-specific? It’s musculoskeletal anatomy and kinesiology — the foundation underneath Pilates, yoga, massage, and strength training alike. You teach the Pilates application; this handles the anatomy your students need to understand it. ### Can we describe it as the anatomy component of our program? Of course. The videos carry our branding, so describe it in your program however suits you. The one thing to avoid is calling it “NPCP-approved”: NPCP doesn’t approve courses. It was built with the updated NPCP requirements in mind. ### Can I embed the videos in my own platform? Yes, under a program agreement. That path includes quarterly enrollment reporting. For smaller programs we generally recommend hosted access — it’s less work for you. ### What are the program agreement tiers? The price per student drops as your year’s total grows, and the whole year is priced at the tier you reach: 1–14 students $80 · 15–25 $76 · 26–40 $72 · 41–60 $68 · 61–100 $64 · 101–150 $60 · 151–200 $56 · 201–400 $52. The same tiers apply whether you register students as you go or sign a program agreement. ### What if my enrollment changes mid-year? Per-student registration has no reconciliation at all — you pay for the students you register, when you register them. Program agreements reconcile at year end, so you’re credited or invoiced against actual enrollment. ### Further Reading - [What the NPCP anatomy requirement actually asks for in 2027](https://3dmusclelab.com/npcp-anatomy-requirements-2027/) - [Pilates accreditation bodies, compared](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/) - [How many anatomy hours does a Pilates teacher training need?](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/anatomy-hours-pilates-teacher-training/) - [Teach anatomy yourself, or outsource it?](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/teach-anatomy-yourself-or-outsource/) ## Take anatomy off your plate Your next cohort needs anatomy. You can build it again, or you can assign it. Questions about fit, pricing, or curriculum mapping? Email David directly at [admin@3dmusclelab.com](mailto:admin@3dmusclelab.com) — you’ll get a real answer from the person who built the course. --- Source: https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/ For Pilates teacher training programs # Pilates accreditation bodies, compared The Pilates world has two organizations with similar names doing genuinely different jobs, and the confusion costs program directors real time. Here’s the plain version. ## The one distinction that matters NPCP credentials individual teachers. PMA accredits programs. Everything else follows from that. If you remember nothing else, remember that sentence. NPCP ### Credentials teachers - **What it certifies**: individual teachers - **How**: the NCPT exam - **Who applies**: your graduates - **Categories**: Mat · Comprehensive - **Result**: a teacher holds the NCPT - **Renewal**: 16 CE hours every 2 years PMA (ITTAP) ### Accredits programs - **What it certifies**: teacher training programs - **How**: curriculum review and accreditation - **Who applies**: you - **Categories**: Mat · Reformer · Comprehensive - **Result**: your program is listed as ITTAP-accredited - **Renewal**: periodic re-review ## Why they have the same history The reason the names get tangled is that they used to be the same thing. NPCP began in **2005** as a program inside the Pilates Method Alliance. It ran under PMA governance for over fifteen years, which is why older articles refer to “the PMA exam.” Same credential, former name. In **2021** it spun off as an independent nonprofit. The split clarified the roles rather than creating new ones. PMA now runs ITTAP for school-level curriculum accreditation. NPCP focuses solely on credentialing individual teachers. If you trained before 2021 and remember a single organization doing both, you’re not misremembering. It did. The teacher credential ## NPCP, in detail The **NCPT**, Nationally Certified Pilates Teacher, is the credential NPCP issues. What sets it apart from a school’s own certificate of completion is that it’s **third-party and NCCA-accredited.** NPCP is the only NCCA-accredited certifying body for Pilates teachers, which means the certification isn’t tied to any single school or lineage. A school certifying its own graduates is attesting they completed its program. The NCPT is an independent assessment of whether they know the material. **Eligibility.** Completion of a comprehensive program of at least **450 hours**, covering Mat, Reformer, Trapeze Table (Cadillac), Wunda Chair, Ladder Barrel, Spine Corrector and Magic Circle. **The exam.** 125 multiple-choice questions over three hours: 100 scored, 25 unscored pilot items. Taken at a testing center or via online proctoring. **Cost.** $300, plus $105 outside the US and Canada. Retake $155. **Maintaining it.** 16 hours of NPCP-approved continuing education every two years, focused on Pilates-related topics, anatomy, or special populations. **What changes in 2027.** From January 1, 2027, eligibility requirements change: Repertoire and Special Populations need an in-person component, while History of Pilates and Anatomy may remain pre-recorded with a supporting quiz. Observation, practice teaching and self-practice may be live-virtual under school supervision. A six-month grace period applies. [Full detail here.](https://3dmusclelab.com/npcp-anatomy-requirements-2027/) The program accreditation ## PMA and ITTAP, in detail **ITTAP**, International Teacher Training Accreditation for Pilates, is the PMA’s accreditation program for Mat, Reformer and Comprehensive teacher trainings. It replaced the earlier PSAP program. ### What it evaluates The educational structure of a program: curriculum, instructional requirements, student assessments, teacher trainer qualifications, and supporting documentation. ### What you get Accredited programs are listed on the PMA’s website, which is where prospective students go to compare programs. For a school competing for enrollments, that listing is the practical value. ### What it deliberately doesn’t Teaching style, method, or lineage. ITTAP is designed to establish minimum educational standards while respecting the diversity of approaches across the profession. It isn’t trying to make everyone teach the same way. ### What applying involves Each category (Mat, Reformer, Comprehensive) has its own Standards Guide setting out exactly what’s required. The application asks for a **narrative** covering: - Your rationale for curriculum structure and sequencing - [How you determined your modules and total hours](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/anatomy-hours-pilates-teacher-training/) - A detailed description of how each required module is delivered **It isn’t enough to teach the material. You have to be able to explain why your curriculum is structured the way it is.** Programs that have grown organically over years often find this the hard part, because the honest answer to “how did you determine your total hours” is sometimes “we didn’t, it evolved.” Complete educational manuals are submitted in English, in a consistent format. Submissions have strict formatting requirements, and incorrectly formatted ones get delayed. Read the Standards Guide for your category before you write anything. ## Which applies to you ### You run a training program ITTAP is the accreditation available to you. NPCP still matters, because your graduates will sit the NCPT and your curriculum has to make them eligible for it. The two aren’t alternatives. You’d be working within NPCP’s eligibility requirements whether or not you pursue ITTAP. ### You’re a teacher The NCPT is your credential. Your program’s ITTAP status doesn’t certify you, though it’s a reasonable signal about the quality of the training you received. ### You’re choosing a program Check both. ITTAP tells you the curriculum has been independently reviewed against a published standard. NPCP eligibility tells you whether you can sit the exam afterward, which matters, because not every program’s hours qualify. Outside the United States ## Australia and New Zealand: the PAA If you’re outside the US, NPCP’s rules aren’t yours. Australasia has its own structure, and it’s stricter than most people expect. The **Pilates Alliance Australasia (PAA)** was established in 2000 as an independent nonprofit regulatory body overseeing the quality and integrity of Pilates education in the region. It sits somewhere between the two American organizations. It approves training providers *and* it registers teachers and studios. What it expects of a course The PAA has publicly stated it expects courses to run **at least 500 hours**, more than NPCP’s 450. More significantly, PAA-approved Professional courses must be **VET accredited**, delivered through a **registered training organization (RTO)**, and deliver graduates a **minimum AQF diploma qualification.** That ties Pilates teacher training into Australia’s national vocational education framework, which means accredited courses appear on the National Register at training.gov.au with their own national course code. The Diploma of Professional Pilates Instruction, for instance, is 10838NAT. What it expects of your faculty This is where the PAA is unusually specific. A course director or principal tutor needs a minimum of **10,000 teaching hours.** Faculty tutors need a minimum of **5,000.** There isn’t an equivalent numeric requirement in the American standards. **Membership tiers.** The PAA registers teachers at Group, Studio and Practitioner levels, with course requirements differing by tier. Studio-level courses must equip graduates to work with clients presenting specific musculoskeletal issues (lordosis, kyphosis, forward head, low back pain, neck, shoulder and knee problems) rather than just apparently healthy bodies. **One detail worth knowing if you deliver anything online.** The PAA’s professional development guidelines require online programs to include **8 to 10 multiple choice or true/false questions per hour of content**, with 1 PDP awarded per hour and a maximum of 15 per program. That’s a professional development standard rather than an initial teacher training one, so don’t map it directly onto your curriculum. But it tells you the PAA takes online assessment density seriously enough to quantify it, which few bodies do. ## AUSactive **AUSactive**, formerly Fitness Australia, handles industry registration for Pilates professionals in Australia. It’s a different layer again: not education accreditation, but professional registration. Registered Pilates Professionals must complete a recognized course, hold current nationally recognized **First Aid** (renewed every three years) and **CPR** (renewed annually), and accumulate Continuing Education Credits: a minimum of **10 CECs** for a 12-month registration, or **20** for 24 months. Usefully for programs working across regions, AUSactive recognizes education approved by the Australian Pilates Method Association, the Pilates Alliance Australasia, **and** the Pilates Method Alliance, so PMA-recognized education carries weight in Australia even though PMA is an American organization. ## Europe and the UK **EuropeActive** handles European professional registration, and **CIMSPA** is the UK’s chartered institute for sport and physical activity. Both publish their own standards and both operate as registration bodies rather than Pilates-specific accreditors. We haven’t reviewed their requirements in the detail we have the others, so check directly rather than taking a general reading. Be wary of any source that treats “the standards” as though there’s one set. **What travels, and what doesn’t.** The rules vary considerably. Hours differ, delivery formats differ, faculty requirements differ, and the whole structure differs. Australia routes Pilates education through a national vocational framework in a way the US simply doesn’t. The **content** doesn’t vary at all. Anatomy is anatomy. A program in Sydney and a program in Munich are teaching the same origins, insertions and actions on the same bodies. What changes is who’s allowed to teach it, in what format, and for how many hours. ## The glossary - **NPCP**: National Pilates Certification Program. Credentials individual teachers. - **NCPT**: Nationally Certified Pilates Teacher. The credential NPCP issues. - **PMA**: Pilates Method Alliance. Nonprofit membership organization, runs ITTAP. - **ITTAP**: International Teacher Training Accreditation for Pilates. Program-level accreditation. - **PSAP**: the predecessor to ITTAP, now phased out. - **NCCA**: National Commission for Certifying Agencies. Accredits certifying bodies. NPCP holds this. - **Comprehensive**: training covering all apparatus, 450+ hours. - **Mat**: training covering mat repertoire only, shorter. ## One thing worth being clear about **No anatomy course is “NPCP-approved” or “ITTAP-accredited.” Those bodies don’t approve curriculum providers.** NPCP credentials teachers. ITTAP accredits whole programs. Neither has a process for approving a [third-party anatomy module](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/teach-anatomy-yourself-or-outsource/), so anyone claiming that approval is describing something that doesn’t exist. What a course can honestly claim is that it **matches the format these standards permit**: pre-recorded with a supporting quiz, in the case of anatomy. That’s a meaningful claim, it’s checkable, and it’s a different one. Ours included. We’re a curriculum provider, not an accrediting body, and we’d rather say so plainly than let a director assume otherwise and find out later. ### Where to check - [NPCP Comprehensive Eligibility Requirements](https://nationalpilatescertificationprogram.org/NPCP/NPCP/Get_Certified/Requirements.aspx) - [NPCP Mat Eligibility Requirements](https://nationalpilatescertificationprogram.org/NPCPMAT/NPCPMAT/Get_Certified/Requirements.aspx) - [PMA ITTAP program and Standards Guides](https://www.pilatesmethodalliance.org/international-teacher-trainer-accreditation-for-pilates) Requirements change. Confirm the current version with whichever body governs your program. For teacher training programs ## The anatomy component, handled. Pre-recorded, self-paced, and quizzed at every module: the format NPCP permits for anatomy. 12 modules, 79 lessons, 15 hours, $80 per student for 12 months of access. [Our anatomy module for Pilates teacher trainings →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) --- Source: https://3dmusclelab.com/anatomy-for-pilates-teacher-training/teach-anatomy-yourself-or-outsource/ For Pilates teacher training programs # Should you teach anatomy yourself, or outsource it? We sell an anatomy course, so read this knowing that. We’ve also tried to write the version we’d want to read if we were on your side of it, because for a decent number of programs, teaching it yourself is the right answer. First, the distinction ## Split “anatomy” in two Most of this gets easier once you separate two things that usually get discussed as one. - **Foundational kinesiology is identical in every program:** what the muscles are, where they attach, what they do. There is no house style for the origin of biceps femoris. - **Applied anatomy is yours:** how you connect structure to repertoire, how you cue it, what you emphasize, the language your graduates leave with. Nothing below is about handing off the second one. The only question is whether the first one is a good use of your hours. The choices ## The four options 01 ### Teach it yourself The most common approach, and free in cash terms. Costs 20 to 30 hours of prep per cohort if you’re building it properly, and considerably more the first time. 02 ### Bring in an instructor Typically $1,500 to $3,000 for a weekend, plus scheduling around their availability. You get live teaching and questions answered in the room. 03 ### Assign a textbook Cheap and no prep. But no assessment, so if you’re working to a standard that requires a quiz supporting the learning outcome, a book alone doesn’t get you there. 04 ### License a course Fixed cost per student, no prep, assessment included. Covers the foundations so the applied teaching stays with you. You give up live teaching of the basics and gain the ability to tailor it in the room. The case for keeping it ## When teaching it yourself is the right call - **You’re genuinely good at it.** If you have an anatomy background and enjoy teaching it, your version will beat anything brought in, because you can connect it to your repertoire as you go, in language your trainees have already heard from you. - **It’s a differentiator.** Some programs are known for their anatomy teaching, and people enroll partly for it. That’s a real reason to keep it in-house. - **You want it woven through rather than blocked.** Much easier when you’re the one teaching, because you can pull an anatomy point into a repertoire session on the fly. ## When outsourcing makes more sense - **Anatomy isn’t your strength.** Excellent Pilates teachers are not necessarily confident on origins, insertions and actions, and trainees can tell. Teaching something you’re shaky on is worse than not teaching it. - **You’re teaching it inconsistently.** If what gets covered depends on who taught it and how much time was left at the end of the day, your graduates aren’t leaving with the same foundation. That’s a quality problem before it’s an accreditation problem. - **Faculty hours are the constraint.** Prep time spent on anatomy is time not spent on the things only you can teach. For most program directors, anatomy is not the highest use of their hours. - **You need documented assessment.** Building, administering and grading quizzes is its own project. If you need per-student records for verification, that’s ongoing work. - **You’re preparing for accreditation.** [ITTAP](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/) asks for documentation of curriculum, assessment and hours. A pre-built module comes with all three, already written. ## The cost comparison, honestly ### Teaching it yourself - **Cash cost**: $0 - **Your time**: 20–30 hrs prep per cohort - **Consistency**: varies by cohort - **Assessment**: you build it - **Live questions**: yes - **Tailored to your repertoire**: yes - **Accreditation docs**: you write them ### Outside instructor - **Cash cost**: $1,500–3,000 per cohort - **Your time**: scheduling and coordination - **Consistency**: varies by instructor - **Assessment**: usually not included - **Live questions**: yes - **Tailored to your repertoire**: sometimes - **Accreditation docs**: you write them ### Licensed course - **Cash cost**: per student - **Your time**: minimal - **Consistency**: identical every time - **Assessment**: included - **Live questions**: no - **Tailored to your repertoire**: no — that stays in your contact hours - **Accreditation docs**: provided Look at cost as a percentage of tuition, not as a number. Licensing is roughly 1 to 2% of what your students are already paying you, and that stays true at six students or sixty, because both sides scale together. Above 15 students, tiered pricing means the percentage drops. Your prep time doesn’t scale that way. It’s 20 to 30 hours whether you teach six students or sixty, which makes it a heavier cost per student at low volume, not a lighter one. Cost is rarely what decides this. What decides it is whether you’re good at teaching anatomy, and what else those hours could be doing. Two programs ## Two scenarios Six students, one cohort a year The director has a movement science background and enjoys teaching anatomy. Licensing would cost less than a weekend instructor but more than nothing, and she’d lose something her program is partly known for. **Keep teaching it.** The prep is amortized over years of reuse, and the material is already built. Thirty students, three cohorts Anatomy is taught by whichever senior teacher is available, which means three different versions a year and no consistent assessment. The director spends most of her prep time on it, and none of that is work only she can do. **License it**, and spend the recovered hours on the repertoire teaching that actually differentiates the program. Most programs are somewhere between these two. The question that usually settles it: *if anatomy took no preparation at all, what would you do with those hours instead?* If the answer is compelling, that’s your answer. ## The option people forget You don’t have to choose one. A common arrangement is to assign a pre-recorded module as **pre-work**, then spend your contact hours **applying** it: connecting anatomy to repertoire, answering questions, working on bodies. The knowledge acquisition happens on the student’s time. Your live hours go to the part that actually needs you in the room. Trainees arrive at a session already knowing where the muscle attaches, so you spend the session on what it means when they see it in a body. It works because the two layers behave differently. Foundational material is the same everywhere, so it can be recorded and tested. Technique can’t be, which is why it belongs in the room. That’s also the arrangement the 2027 NPCP changes push toward: anatomy pre-recorded, repertoire in person. [More on that here.](https://3dmusclelab.com/npcp-anatomy-requirements-2027/) Due diligence ## What to look for if you do license Four things worth checking before you commit. 01 ### Format and assessment Does the delivery format match what your standard permits, and does it include the assessment that permission is conditional on? 02 ### Documentation Can you get a [curriculum outline](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/anatomy-hours-pilates-teacher-training/) listing modules, lessons, hours and where assessment falls? You’ll need it for accreditation, and for mapping against your own syllabus. 03 ### Access period Does student access last long enough for a program running 9 to 18 months? A six-month access period on a fourteen-month program creates support problems you’ll be handling personally. 04 ### Records Can you demonstrate which students completed it, and when? Certifying bodies audit verification, and “we assigned it” isn’t evidence. ## What we’d actually say If you enjoy teaching anatomy and you’re good at it, keep teaching it. Nothing bought in will connect it to your repertoire the way you can, and there’s real value in a program whose director teaches the foundations personally. If you’re teaching it because someone has to, and it’s eating prep time you’d rather spend elsewhere, that’s the case for handing it off, and the format standards permit for anatomy makes it the easiest piece of your curriculum to hand off cleanly. Either way, keep the applied teaching. The only part worth handing off is the layer that’s identical in every program anyway. If you’re weighing the outsourced option ## 12 modules, 79 lessons, 15 hours. Foundational kinesiology only — no technique, no cueing, no repertoire. Quizzed throughout, $80 per student for 12 months of access. Pre-recorded and self-paced, the format certifying bodies permit for anatomy. Programs in the US, Mexico, Germany and Australia already run it. [Anatomy course for Pilates teacher trainings →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) --- Source: https://3dmusclelab.com/anatomy-for-pilates-teacher-training/anatomy-hours-pilates-teacher-training/ For Pilates teacher training programs # How many anatomy hours does a Pilates teacher training need? Short answer: **there isn’t a mandated number.** That surprises most people who go looking for one, and it’s the first thing worth understanding. ## What the standards actually specify NPCP’s comprehensive pathway requires **450 hours**, covering Mat, Reformer, Trapeze Table, Wunda Chair, Ladder Barrel, Spine Corrector and Magic Circle. The Mat pathway is shorter. What the requirements specify is which **categories** a program must cover, and **how each may be delivered**, not how many hours to spend on each. From January 1, 2027, Repertoire and Special Populations need an in-person component. History of Pilates and Anatomy may be pre-recorded with a supporting quiz. Observation, practice teaching and self-practice may be live-virtual under school supervision. [Full detail on the 2027 changes here.](https://3dmusclelab.com/npcp-anatomy-requirements-2027/) So the constraint on anatomy is a **format** constraint, not an **hours** constraint. Nobody is going to tell you twelve hours is enough and eight isn’t. The better question ## Which means the real question is different Not *how many hours do I have to teach?* but **how many hours does it take for a trainee to actually know this material?** A trainee finishing your program should be able to name the major muscles, say where they attach, describe what they do, and connect that to what they’re seeing in a body on a reformer. That’s the bar. It’s the same bar whether you spend eight hours on it or thirty. Which is a harder question than an hours count, and a more useful one. In practice ## What programs typically do There’s no published survey, so treat this as observation rather than data. Across the programs we work with, anatomy tends to occupy somewhere between **10 and 20 hours** of a comprehensive program. Some deliver it as a discrete block early on. More deliver it distributed: a module here, a module there, revisited alongside the repertoire it explains. **The distributed approach generally works better.** Anatomy taught once in week two and never mentioned again doesn’t stick. Anatomy taught alongside the movement it explains does, because the trainee has somewhere to put it. The practical version: teach the shoulder module in the block where you’re working on shoulder mechanics. Teach the hip module alongside turnout. The anatomy stops being a separate subject and becomes the explanation for what they’re already doing. Whether you [**teach that anatomy yourself or bring in a module**](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/teach-anatomy-yourself-or-outsource/) is a separate decision, and we’ve laid out both sides. ## Why hours are the wrong unit anyway Contact hours measure **delivery**, not learning. A trainee who sits through twelve hours of anatomy lecture and retains a third of it has technically met an hours requirement and hasn’t learned the material. A trainee who works through eight hours of well-structured content with retrieval practice built in may know it considerably better. This is why the standards specify **assessment** rather than duration. “A quiz must support the learning outcome” is asking whether they know it, not how long you spent telling them. If you’re designing an anatomy component, design it around what they’ll be able to do at the end. The hours will be whatever they need to be. ## What retention actually requires Worth a short detour, because it changes how you’d allocate time. Anatomy is a memorization-heavy subject taught to people who mostly didn’t come from a science background. Dancers, athletes, career changers, people who haven’t opened a textbook in twenty years. The failure mode isn’t that the material is too hard. It’s that it goes in and doesn’t stay. Three things reliably improve retention, and none of them is “more hours”: 01 ### Retrieval before reveal Asking a trainee to recall where a muscle attaches *before* showing them beats showing them twice. 02 ### Multiple input channels Seeing a structure, hearing it described, and reading it at the same time encodes better than any one alone. 03 ### Spaced repetition Meeting a muscle in week three and again in week nine beats meeting it twice in week three. An hours count captures none of that. Which is another reason the standards don’t set one. For accreditation ## What to document Whatever you allocate, be able to show: - **Which categories your anatomy content covers**, and how it maps to the requirement - **How it’s delivered**, and whether that format is permitted for the category - **How it’s assessed**, and that you hold the results - **Approximate hours**, because accrediting bodies ask even where they don’t mandate That last point matters more than it sounds. [**ITTAP applications specifically**](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/) **ask for a narrative explaining how your modules and total hours were determined.** If your honest answer is “it evolved,” that’s a gap to close before applying. Not because the hours are wrong, but because you need to be able to account for them. ## For reference Our own anatomy module runs **15 hours** across 12 modules and 79 lessons, with a quiz ending each module. That isn’t offered as the correct number. It’s offered because it’s a **documented** number. A program using it can put 15 hours in its ITTAP narrative and point at a curriculum outline that supports it. Which, for accreditation purposes, matters more than whether it’s 12 or 18. ### Where to check - [NPCP Comprehensive Eligibility Requirements](https://nationalpilatescertificationprogram.org/NPCP/NPCP/Get_Certified/Requirements.aspx) - [PMA ITTAP Standards Guides](https://www.pilatesmethodalliance.org/international-teacher-trainer-accreditation-for-pilates) Requirements change. Confirm the current version with whichever body governs your program. For teacher training programs ## 15 documented hours, quizzed throughout. 12 modules, 79 lessons, 15 hours, with a quiz at the end of every module. Pre-recorded and self-paced, the format NPCP permits for anatomy. $80 per student for 12 months of access. [The full module and lesson breakdown →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) --- Source: https://3dmusclelab.com/contact/ # Contact Us ## The most common questions Most of what people write in about is answered below. If yours isn’t here, the form at the bottom of this page comes straight to us. ### Having trouble logging in? Your username is the email address you signed up with, not a separate name you chose. Forgot password? [Reset it here](https://my.3dmusclelab.com/login/?action=lost) using that email address. If you get an invalid email error, it usually means a typo, or that you signed up with a different address than the one you're trying. Worth checking any other addresses you use. **Getting logged out repeatedly?** That's almost always a stale browser cache. [Refreshyourcache.com](https://www.refreshyourcache.com/en/home/) has clear instructions for every browser. ### Can't find your course? First, check whether you're actually logged in. Look at the top right of this page. If it says **Login**, you're not. [Log in here](https://my.3dmusclelab.com/login/) and you'll land on your courses. If it says **Logout**, you're already in. Click **Go To Course** and you're there. ### Videos not playing properly? Video is delivered through Vimeo, which has infrastructure worldwide, so playback problems are usually local. Check your connection first, then make sure your browser is up to date. Those two account for nearly everything we see. Lessons stream rather than download. That keeps your access working across every device you use without you having to manage files, and it means the library stays current as material is updated. If it's still not behaving after checking both, write to us below and tell us which lesson and which browser. ### How do I cancel my subscription? Log in, and you'll land on your course outline. At the bottom of that page, click **Account Details**. Under the **Subscription** heading, cancel the subscription. That stops the billing and leaves your account intact, so your history and any other access you hold stay where they are. Closing the account is a separate, permanent action further down the same page, and it isn't what you want if you're only stopping payments. ## Still need us? Send us a message and we’ll get back to you as soon as we can. Office hours are 9am to 5pm Eastern, Monday to Friday. We take weekends off, and we hope you do too. If you’d rather email directly: [admin@3dmusclelab.com](mailto:admin@3dmusclelab.com) --- Source: https://3dmusclelab.com/anatomy-and-muscle-online-course-details/ For Pilates teachers, yoga teachers, massage therapists & trainers # Learn your muscles. Actually remember them. Every anatomy course you've tried felt like it was written for a medical student. This one wasn't. **79 lessons. 65 muscles. Taught in 3D.** See it move. Understand it. Keep it. See what's inside [Try a free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ![3D anatomical model of the semimembranosus muscle showing origin and insertion](https://3dmusclelab.com/wp-content/uploads/2019/02/semimembranosus-mus.jpeg) 65 muscles covered 79 lessons 3D visual models 30 day guarantee ## Anatomy you can actually use in the room. Every other resource Flat diagrams. Dense text. Forgotten by Friday. Most anatomy books and courses are built for people studying to become doctors — not for the Pilates teacher who needs to cue a client's hip flexors precisely, the yoga teacher working out why a student's hamstring keeps pulling, or the massage therapist who needs to know exactly where the psoas attaches. The information is there. But it never sticks. 3D Muscle Lab See it move. Understand it. Keep it. Every muscle is taught in 3D — you see exactly where it sits, where it attaches, and what happens when it contracts. Then the quiz system reinforces it until it's genuinely in long-term memory. **Not memorized for a test. Actually known.** 65 Muscles covered in full 3D 79 Video lessons with David 4 Learning formats per muscle 30 Day money-back guarantee How each lesson works ## Four steps. One muscle. Locked in. 1. 01 **Bony landmarks** Before the video, you preview the attachment points on the skeleton. **Try to recall where the muscle attaches before opening each toggle.** That retrieval attempt is the first layer of memory work. ![3D render of the ischial tuberosity bony landmark](https://3dmusclelab.com/wp-content/uploads/2019/02/ischial-tuberosity-below-bl.jpeg) 2. 02 **Watch the lecture** David walks through origin, insertion, action, and clinical relevance — with the 3D model on screen the whole time. **Plain language. No unnecessary jargon.** ![3D anatomical model of the biceps femoris muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/biceps-femoris-mus.jpeg) 3. 03 **Look, listen, read** Each muscle gets its own 3D image with audio narration. Look at the model, listen, and read at the same time. **Three input channels at once — retention goes up significantly.** ![3D anatomical model of the semitendinosus muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/semitendinosus-mus.jpeg) 4. 04 **Test yourself** Multiple quiz styles — recall, recognition, image-based — reinforce the material in different ways. **This is what separates knowing a muscle from having read about one.** ![3D render of the pes anserine attachment site](https://3dmusclelab.com/wp-content/uploads/2019/02/pes-anserine-bl.jpeg) ## See what's inside No Signup ### A sample lesson The hamstring group, taught exactly the way the course teaches it. Bony landmarks in 3D, the video lecture, audio cards, and a quiz at the end. Nothing to fill in. Open it and start. [See the sample →](https://3dmusclelab.com/free-hamstring-lesson/) Three Full Lessons ### Free lessons inside the course Three complete lessons on your own login, working the way your students would. We'll need an email to set the account up. No card, nothing to cancel. [Three free lessons →](https://my.3dmusclelab.com/join/free-lesson/) What’s in the course ## 12 modules. 79 lessons. 15 hours. The course works joint by joint through the whole body. Every muscle is covered twice — once for its bony landmarks, once for its attachments and actions — and every module ends with a quiz. Click any module to see what's inside. ### 01 Introduction to Anatomy & Muscle Function 1 lesson Overview and intentions for the course. ### 02 Fundamental Anatomy Concepts 5 lessons Planes of the body · Directional terms · Basic movements · Joint types and shapes · **Quiz** ### 03 The Muscular System 3 lessons Muscle construction · Muscle contractions · **Quiz** ### 04 Muscles That Move the Forearm 8 lessons Biceps Brachii · Brachialis · Triceps Brachii — each covered as bony landmarks, then attachments and actions · **Quiz** ### 05 Muscles That Move the Scapula 12 lessons Levator Scapulae · Rhomboids · Trapezius · Serratus Anterior · Pectoralis Minor — each covered as bony landmarks, then attachments and actions · **Quiz** ### 06 Muscles That Move the Shoulder 12 lessons Rotator Cuff (supraspinatus, infraspinatus, teres minor, subscapularis) · Pectoralis Major · Latissimus Dorsi · Teres Major · Deltoids · **Quiz** ### 07 Muscles That Move the Knee 6 lessons Quadriceps Group (rectus femoris, vastus lateralis, vastus intermedius, vastus medialis) · Hamstrings Group (semitendinosus, semimembranosus, biceps femoris) · **Quiz** ### 08 Muscles That Move the Ankle 10 lessons Tibialis Anterior · Fibularis (Peroneus) Longus · Soleus · Gastrocnemius · **Quiz** ### 09 Muscles That Move the Hip 12 lessons Adductor Group (pectineus, adductor brevis, adductor longus, gracilis, adductor magnus) · Sartorius · Gluteal Group (minimus, medius, maximus) · Deep Six Lateral Rotators · Iliopsoas · **Quiz** ### 10 Muscles That Move the Neck 8 lessons Sternocleidomastoid · Scalenes · Splenius Group (capitis, cervicis) · **Quiz** ### 11 Muscles That Move the Trunk 8 lessons Abdominal Muscles Group · Quadratus Lumborum · Erector Spinae Group · **Quiz** ### 12 Muscles Involved With Breathing 4 lessons Diaphragm · External Intercostals · Internal Intercostals · **Quiz** ## Taught by someone who gets your world. ![David Keil, anatomy educator and author of Functional Anatomy of Yoga](https://3dmusclelab.com/wp-content/uploads/2018/07/david-keil-profile-800px.png) - Teaching kinesiology since 1999 - Author, *Functional Anatomy of Yoga* - Licensed Massage Therapist, Neuromuscular Therapist - M.S. Exercise Physiology - Programs using this course in the US, Mexico, Germany, and Australia David Keil — M.S. Exercise Physiology, LMT, NMT Kinesiology was the first course I taught, back in 1999, at a massage school in Miami. I was immediately confronted with the real problem: taking a genuinely complex subject and making it land for students from every walk of life — dancers, athletes, career changers, people who hadn't opened a science textbook in twenty years. I've spent the years since teaching functional anatomy to movement professionals around the world, and writing *Functional Anatomy of Yoga* to do the same thing in print: take the complexity out without dumbing the content down. > "I kept meeting brilliant practitioners who were held back by anatomy resources written for medical students. I built this course because seeing a muscle move in 3D is worth more than any diagram." From practitioners like you ## What happens when anatomy finally clicks. > "Before 3D Muscle Lab, I couldn’t make muscles, their attachments, and the related actions come alive in my mind’s eye. I could only find flat pictures with words, words, words. 3D Muscle Lab showed me the body moving and how the muscles are attached. It all comes alive and makes sense." > > Kate Harper Yoga teacher & anatomy student > "I used to have headaches just trying to learn the names and terminology. David’s instruction is so clear. Even for someone like me who speaks Spanish and not much English — I could understand the whole program. Learning anatomy couldn’t be easier." > > Paulina R. Pilates instructor, Spain For teacher training programs ## Running a Pilates teacher training? There’s a version of this for you. If you run a Pilates or movement teacher training, you can license this course for your students instead of building an anatomy module yourself. Pre-recorded, self-paced, and quizzed at every stage — the format certifying bodies permit for anatomy. Programs in the US, Mexico, Germany, and Australia already run it. [See program licensing →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) Ready to start? ## 65 muscles. One course. Yours to keep. Monthly, annual, or lifetime access — all plans include the full 79-lesson course with every 3D model, bony landmark, audio card, and quiz. **30-day money-back guarantee.** [See pricing and get started](https://3dmusclelab.com/pricing/) Or [try a free lesson first](https://3dmusclelab.com/free-hamstring-lesson/) — no signup required. --- Source: https://3dmusclelab.com/free-hamstring-lesson/ Free lesson - no signup required # THE HAMSTRINGS A complete 3D Muscle Lab lesson — the same format used in the full course. See how it works, then decide if it's right for you. What you’ll learn ## Your hamstrings in full 3D Most practitioners have a rough idea of what the hamstrings do — but **seeing them in 3D changes everything.** You'll learn exactly where each muscle attaches, what it does, and how to remember it. - Biceps Femoris - Semimembranosus - Semitendinosus This is the **bony landmark lesson** for the group — where each muscle attaches on the skeleton, in **3D with audio**, followed by a **quiz** so the information actually sticks. About 15–20 minutes. **Origin, insertion and action get their own lesson right after this one.** ## HOW THIS LESSON WORKS 1. 1 **Preview the bony landmarks**Click each toggle to reveal where the hamstrings attach on the skeleton. **Try to recall the answer before opening it** — that's the first layer of memory work. 2. 2 **Watch the lecture**David walks you through every hamstring attachment site on the skeleton, in plain language, with the 3D model on screen throughout. 3. 3 **Look, listen and read**Each landmark gets its own 3D image card with audio. Click play, look at the model, and read along. **Three input channels at once = better retention.** 4. 4 **Test yourself with the quiz**Five questions on what you just covered. Answer them and see your score — this is what makes the information stay with you, not just for the exam, but for when you're in the room with a client. The three muscles this group is built from ![Biceps Femoris Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/biceps-femoris-mus.jpeg) ***Biceps Femoris**long & short head* ![Semimembranosus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/semimembranosus-mus.jpeg) ***Semimembranosus**Medial hamstring* ![Semitendinosus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/semitendinosus-mus.jpeg) ***Semitendinosus*** 1 ## Preview the bony landmarks Click each section title to reveal — try to recall the answer before opening it ### ISCHIAL TUBEROSITY - Origin ![Ischial Tuberosity](https://3dmusclelab.com/wp-content/uploads/2019/02/ischial-tuberosity-below-bl.jpeg) ### Ischial Tuberosity All three hamstrings originate from the ischial tuberosity — the bony landmark you sit on. The long head of biceps femoris, semimembranosus, and semitendinosus all share this common origin point on the pelvis. ### LINEA ASPERA - Biceps Femoris Short Head Origin ![Linea Aspera](https://3dmusclelab.com/wp-content/uploads/2019/02/linea-aspera-wide-bl.jpeg) ### Linea Aspera The short head of biceps femoris has a separate origin — the linea aspera, a rough ridge running down the posterior femur. This is what makes the biceps femoris unique among the hamstrings: it crosses only the knee, not the hip. ### HEAD OF FIBULA - Biceps Femoris Insertion ![Head of the Fibula](https://3dmusclelab.com/wp-content/uploads/2019/02/head-of-fibula-zoom-bl.jpeg) ### Head of the Fibula Biceps femoris inserts on the head of the fibula at the lateral side of the knee. This is why biceps femoris can assist with lateral rotation of the knee — something the medial hamstrings can't do. ### PES ANSERINE - Medial Hamstring Insertions ![Pes Anserine](https://3dmusclelab.com/wp-content/uploads/2019/02/pes-anserine-bl.jpeg) ### Pes Anserine Semitendinosus inserts at the pes anserine — "goose foot" — on the medial tibia, alongside gracilis and sartorius. Semimembranosus inserts slightly higher on the medial tibial condyle. Both assist medial rotation of the knee. 2 ## Watch the lecture David walks through the bony landmarks of the hamstring group — every attachment site, in context 3 ## Look, listen and read Each landmark — click play on the audio, look at the 3D model, read along ![Ischial Tuberosity](https://3dmusclelab.com/wp-content/uploads/2019/02/ischial-tuberosity-below-bl.jpeg) **Ischial Tuberosity** ![Linea Aspera](https://3dmusclelab.com/wp-content/uploads/2019/02/linea-aspera-wide-bl.jpeg) **Linea Aspera** ![Head of the Fibula](https://3dmusclelab.com/wp-content/uploads/2019/02/head-of-fibula-zoom-bl.jpeg) **Head of the Fibula** ![Pes Anserine](https://3dmusclelab.com/wp-content/uploads/2019/02/pes-anserine-bl.jpeg) **Pes Anserine** ![Posterior Medial Tibial Condyle](https://3dmusclelab.com/wp-content/uploads/2019/02/post-medial-tibial-condyle-bl.jpeg) **Posterior Medial Tibial Condyle** ## See what's inside Three Full Lessons ### Free lessons inside the course Three complete lessons on your own login, working the way your students would. We'll need an email to set the account up. No card, nothing to cancel. [Three free lessons →](https://my.3dmusclelab.com/join/free-lesson/) What comes next This is the bony landmark lesson — where the hamstrings attach, and what those attachment sites are called. **The following lesson takes the same three muscles through origin, insertion, and action**, with its own video, its own 3D muscle cards, and its own quiz. Every muscle group in the course is built as a pair like this. 4 ## Test yourself Why the quiz matters Reading about a muscle once is not the same as knowing it. Retrieving it from memory is what moves it into long-term storage. **Five questions, no signup, no email.** Answer them the way your students would, and see how much of this stuck. That’s one muscle group ## There are 64 more in the full course Every muscle is taught the same way — 3D models, bony landmarks, audio, and quizzes. Built for yoga teachers, massage therapists, and trainers who need anatomy to actually stick. [See The Full Course](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [View Pricing](https://3dmusclelab.com/pricing/) --- Source: https://3dmusclelab.com/learn-muscles-blog/ # Learn Muscles Blog Need to learn your muscles? Studying kinesiology as part of a course or just want to understand your muscles? You're in the right place! [![pectoralis minor muscle](https://3dmusclelab.com/wp-content/uploads/2026/08/pectoralis-minor.jpg) Muscles The Pectoralis Minor Muscle The pectoralis minor muscle is a small deep muscle that contributes to balanced shoulder and arm position, and can even assist with respiration.](https://3dmusclelab.com/the-pectoralis-minor-muscle/) [![A curriculum document and calendar on a desk, representing Pilates teacher training programs reviewing their curriculum ahead of the January 2027 NPCP deadline](https://3dmusclelab.com/wp-content/uploads/2026/09/npcp-anatomy-requirements-2027.webp) How We Learn What the NPCP anatomy requirement actually asks for in 2027 NPCP's updated eligibility takes effect January 1, 2027. Repertoire and Special Populations need a live component. Anatomy can stay pre-recorded.](https://3dmusclelab.com/npcp-anatomy-requirements-2027/) [![Pelvic Floor Muscles](https://3dmusclelab.com/wp-content/uploads/2026/07/pelvic-floor-muscles.jpg) Muscles The Pelvic Floor Muscles Pelvic floor muscles support our organs above. Contraction and relaxation of these muscles are necessary for healthy urinary and bowel continence.](https://3dmusclelab.com/pelvic-floor-muscles/) [![Muscle Strengthening](https://3dmusclelab.com/wp-content/uploads/2026/06/muscle-strengthening.jpg) Anatomical Applications What Do We Mean By Muscle Strengthening? Exactly what happens during the multiple types of muscle strengthening is unclear, but maintaining muscle strength is clearly beneficial.](https://3dmusclelab.com/muscle-strengthening/) [![Pectoralis Major Muscle](https://3dmusclelab.com/wp-content/uploads/2026/05/pectoralis-major-muscle.jpg) Muscles The Pectoralis Major Muscle The pectoralis major muscle's arrangement in multiple overlapping myofascial bands contributes to its many types of actions.](https://3dmusclelab.com/pectoralis-major/) [![Deltoid Muscles](https://3dmusclelab.com/wp-content/uploads/2026/04/deltoid-muscle.jpg) Muscles The Deltoid Muscles The deltoid muscles are superficial muscles of the shoulder with three distinct sets of fibers that make them versatile for action and stabilization.](https://3dmusclelab.com/deltoid-muscles/) [![The Complex Lower Back](https://3dmusclelab.com/wp-content/uploads/2026/03/low-back.jpg) Anatomy And Physiology The Complex Low Back The complexity created by the many structures that relate to each other in the low back makes it vulnerable to potential dysfunction](https://3dmusclelab.com/the-complex-low-back/) [![Quadratus Lumborum Muscle](https://3dmusclelab.com/wp-content/uploads/2026/02/quadratus-lumborum.jpg) Muscles The Quadratus Lumborum Muscle The quadratus lumborum muscle attaches to our lumbar spine, 12th rib, and ilium of our pelvis. It affects a wide range of movements.](https://3dmusclelab.com/quadratus-lumborum-muscle/) [![Anatomical Effects of Sitting Posture](https://3dmusclelab.com/wp-content/uploads/2026/01/sitting-posture.jpg) Anatomical Applications Anatomical Effects Of Sitting Posture Reduce negative impacts of sitting posture by sitting with a more biomechanically ideal posture, and taking frequent breaks from sitting.](https://3dmusclelab.com/sitting-posture/) [![Hip Labral Tear](https://3dmusclelab.com/wp-content/uploads/2025/12/larbral-tear.jpg) Injuries What Is A Labral Tear? A labral tear happens when the labrum, fibrocartilaginous tissue that connects the cartilage that lines the socket of our hip and shoulder joints, tears.](https://3dmusclelab.com/labral-tear/) [![Whiplash Anatomy](https://3dmusclelab.com/wp-content/uploads/2025/11/whiplash-injury.jpg) Injuries An Anatomical Exploration Of Whiplash Whiplash occurs when our head and neck are thrown into an extreme series of hyperextension and hyperflexion movements after an impact.](https://3dmusclelab.com/whiplash/) [![Brachialis and Coracobrachialis Muscles](https://3dmusclelab.com/wp-content/uploads/2025/10/brachialis-coraco.jpg) Muscles Brachialis And Coracobrachialis Muscles Brachialis initiates flexion of the forearm at the elbow and coracobrachialis does arm adduction. Both of these muscles assist with additional actions.](https://3dmusclelab.com/brachialis-and-coracobrachialis-muscles/) [![Biceps brachii and triceps brachii](https://3dmusclelab.com/wp-content/uploads/2025/09/biceps-triceps.jpg) Muscles The Biceps and Triceps Muscles: Forearm Movers The biceps and triceps are important muscles for positioning our forearms in order to grasp things with our hands.](https://3dmusclelab.com/biceps-and-triceps/) [![Bones and Aging](https://3dmusclelab.com/wp-content/uploads/2025/08/aging-bone-structure.jpg) Anatomy And Physiology What Happens To Bones When We Age? Changes to our bones, including a decline in mass, happen as we age. Weight-bearing exercise and appropriate nutrition can slow that decline.](https://3dmusclelab.com/bones-when-we-age/) [![Muscles and Aging](https://3dmusclelab.com/wp-content/uploads/2025/07/muscle-aging.jpg) Muscles What Happens To Muscles When We Age? Skeletal muscle mass, strength, and tone decline when we age. We can slow the age-related decline of muscles with a variety of exercises.](https://3dmusclelab.com/muscles-when-we-age/) [![What Is A Meniscus Tear?](https://3dmusclelab.com/wp-content/uploads/2025/06/meniscus-tear.jpg) Injuries What Is A Meniscus Tear? A meniscus tear is a tear to the semi-circular pieces of cartilage located at the top of the tibia, where it meets the femur in our knee joint.](https://3dmusclelab.com/meniscus-tear/) [![An Exploration of the Ribcage](https://3dmusclelab.com/wp-content/uploads/2025/05/ribcage.jpg) Anatomy And Physiology An Exploration Of The Ribcage Our ribcage has several essential functions including protection of our organs, a role in breathing, and creation of red blood cells.](https://3dmusclelab.com/ribcage/) [![Muscular Actions of Breathing](https://3dmusclelab.com/wp-content/uploads/2025/04/diaphragm-breathing.jpg) Anatomy And Physiology Muscular Actions Of Breathing: What Happens When We Breathe? The muscular action of breathing always includes the diaphragm. We may also recruit secondary breathing muscles, like the SCM and scalenes.](https://3dmusclelab.com/muscular-actions-breathing/) [![Teaching Pilates aids musculoskeletal conditions](https://3dmusclelab.com/wp-content/uploads/2025/03/pilates-teacher-training.jpg) Anatomical Applications Kinesiology Applied: Teaching Pilates Aids In Managing Musculoskeletal Conditions Teaching Pilates exercises positively affected older adults with musculoskeletal issues like back pain, osteoporosis, neck pain, and osteoarthritis.](https://3dmusclelab.com/teaching-pilates-aids-musculoskeletal/) [![Quadriceps Muscles](https://3dmusclelab.com/wp-content/uploads/2025/02/quadriceps-muscle-h.jpg) Muscles This is where you enter the title of the new post The quadriceps are a group of four muscle bellies on the anterior thigh. These large muscles are important for powerful leg and hip movements.](https://3dmusclelab.com/quadriceps-muscles/) [![Sternoclavicular and Acromioclavicular Joints](https://3dmusclelab.com/wp-content/uploads/2025/01/shoulder-complex.jpg) Anatomy And Physiology The Sternoclavicular And Acromioclavicular Joints: Completing The Shoulder Complex The sternoclavicular and acromioclavicular joints are small but important joints that allow our shoulder complex to create a full range of movement.](https://3dmusclelab.com/sternoclavicular-and-acromioclavicular-joint/) [![An Ankle Sprain](https://3dmusclelab.com/wp-content/uploads/2024/12/ankle-sprain-1.jpg) Injuries What Happens In An Ankle Sprain? An ankle sprain happens when we over-stretch or tear the ligaments and sometimes tendons around our ankle joint after abrupt forceful movements](https://3dmusclelab.com/ankle-sprain/) [![Anatomical Terms for Movement](https://3dmusclelab.com/wp-content/uploads/2024/11/anatomical-terms-1.jpg) Anatomical Applications Anatomical Terms For Movements Anatomical terms for movement help us clearly communicate what and how we’re observing movement in the body.](https://3dmusclelab.com/anatomical-terms-for-movements/) [![Anatomical Terms For Body Location And Relative Position](https://3dmusclelab.com/wp-content/uploads/2024/10/anatomical-terms.jpg) Anatomical Applications Understanding Anatomical Terms For Location And Relative Position Anatomical terms for location help us describe where structures are located in the body and how they are positioned relative to other structures.](https://3dmusclelab.com/anatomical-terms-location-position/) 1 [2](https://3dmusclelab.com/llms-full.txt/page/2/) … [5](https://3dmusclelab.com/llms-full.txt/page/5/) [Next »](https://3dmusclelab.com/llms-full.txt/page/2/) --- Source: https://3dmusclelab.com/pricing/ # Choose the plan that's right for your pocket ## Monthly Recurring We offer a low monthly subscription price if you just need the information for a short time. - Instant access - Monthly recurring payment - Cancel anytime - Refund within 30 days **$20**/month [buy now](https://my.3dmusclelab.com/join/monthly/) RECOMMENDED ## 1 Year Access We offer a low annual subscription price if you need the information for up to 12 months. - Instant access - One time payment - Refund within 30 days **$120** [buy now](https://my.3dmusclelab.com/join/annual/) BEST VALUE ## Lifetime Access You can always have access to this information. This is the most cost effective option. - Instant access - One time payment - Refund within 30 days **$199** [buy now](https://my.3dmusclelab.com/join/lifetime/) Need more information? [Click here for more details](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What people are saying about the course > ### Easy to retain... > > David's anatomy course is easy to understand and follow. The information is clear and the videos provide imagery that is easy to retain. Overall, this course is a great tutorial for students or refresh course for experienced therapists. > > ![Adrian](https://3dmusclelab.com/wp-content/uploads/2019/08/adrian-testimonial.jpg) Adrian Massage Therapist > ### Essential > > David Keil’s way of sharing complex anatomical knowledge, with his simple and easy to assimilate approach, has found it’s pinnacle! > > The multiple layers of content delivery within the course will really help you to grasp/master deeper anatomy/movement principles and the bespoke graphical representations that David has created are stunning. This course will take your knowledge, understanding and ultimate confidence in really knowing anatomy to the next level. Essential! > > ![SCOTT JOHNSON](https://3dmusclelab.com/wp-content/uploads/2019/08/scott-johnson.jpg) SCOTT JOHNSON [Yoga Teacher - Stillpoint Yoga London](https://www.stillpointyogalondon.com/) ## Frequently Asked Questions ### How long will I have access? That depends on the method you choose at purchase. By far the best value is to purchase lifetime access. ### What if I want a refund? We are happy to offer you a refund within the first 30 days. ### Will I have access to the entire course all at once? Absolutely ### Do I need any books to go along with this course? No. However, if you are in school, it would be helpful to use your books to make sure you are using the same exact attachment points that your instructor uses. There are slight variations across the kinesiology world in the way that some attachment points are described. ### How do I cancel my monthly subscription? Log in at [my.3dmusclelab.com](https://my.3dmusclelab.com/) (your username is your email address) and click **Account** at the top of the page. Next to your Monthly plan, click **Cancel subscription**, then **Cancel my subscription**. Nothing more is charged, and you keep the full course until the end of the month you’ve already paid for. Your progress is kept if you come back. --- Source: https://3dmusclelab.com/sitting-posture/ Author: David Keil · Updated: 2026-05-21 Anatomical Applications # Anatomical Effects Of Sitting Posture ![Anatomical Effects of Sitting Posture](https://3dmusclelab.com/wp-content/uploads/2026/01/sitting-posture.jpg) What movement do we do more than any other these days? It’s sitting. We sit in the car, at our desk, and probably on the couch in front of the TV. Sitting is something we probably do for more hours than any other activity, possibly even more than sleeping. According to one reference, those in Western cultures typically sit for 8-11 hours per day, yet we probably haven’t considered its impacts. So what effect does all this sitting have on our body? What happens, anatomically, when we sit? Can we sit better? In this article, we’ll explore some answers to these questions and look more closely at sitting through the lens of anatomy. ## Anatomy of sitting posture There is one thing that’s true anatomically for all the ways that we sit. We remove the legs from the job they do in supporting us when we switch from standing to sitting. The pelvis becomes our base. In order to do that, we [flex our hip joints](https://3dmusclelab.com/anatomical-terms-for-movements/). If we’re standing or lying on our back, our [hip joints](https://3dmusclelab.com/whiplash/) are in roughly what we describe as neutral. That is, they’re not flexed and making the angle at the hip joint smaller. Neither are the hip joints extended, making the angle at the hip joint larger. ### Slumping However, not surprisingly, much of what happens to our body anatomically when we sit depends on how we sit. The biomechanics of what happens in our lumbar spine, for example, change depending on whether we’re slumped, either in a chair or on the floor, or whether we are sitting tall and erect on the edge of a chair or stool. If we slump, we typically roll onto the posterior part of our ischial tuberosities, or even behind them, and flex our lumbar spine. Then, in order to get our eyes gazing back out to the horizon, or computer screen, we make additional compensations along our thoracic and cervical spines [to lift our head](https://3dmusclelab.com/forward-head-posture/). ### Sitting tall In contrast, when we sit tall and erect in a chair or on the edge of a stool, we are sitting on the anterior portion of our ischial tuberosities, with our lumbar spine slightly extended. While we may still make creative compensations with the thoracic and cervical portions of our spine, it is generally easier to stack our torso and head over our pelvic and lumbar base if we have our pelvis and lumbar spine in this position. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Issues with sitting ### Negative effects of being sedentary Why does sitting get such a bad rap these days? There are really two separate issues with lengthy periods of sitting. One is that if we’re seated for a long period of time, obviously, we’re sedentary. And, regularly spending long stretches of time being sedentary has negative consequences for our health, regardless of what position our body is in. There are many problems associated with increased hours of being sedentary. Significant sedentary time is correlated with negative effects on cardiovascular and metabolic health, and is even associated with negative effects on cognitive function. ### Problems with sitting posture Separately, the issue is the posture of sitting itself. Sitting is not necessarily a bad posture per se, but specifically how we sit may be more or less ideal. Often, our choice of sitting posture is less biomechanically ideal. We slouch in chairs or lounge on couches. We stop training our body to hold itself upright when we sit. All of the postural adaptations to a lengthy session in a slumped seated position can add up to aches and pains. Negative effects of the many variations of slumping [postures](https://3dmusclelab.com/posture-and-smartphone/) include increased back and [neck pain](https://3dmusclelab.com/trapezius-computer-posture/), other body aches and pains, and increased [muscle](https://3dmusclelab.com/muscles-when-we-age/) fatigue, even for [daily functional tasks](https://3dmusclelab.com/functional-movement/). Poor sitting posture specifically can also increase pressure on the lumbar vertebral discs and exacerbate issues with the low back. Finally, there is the effect of maintaining any one posture for hours each day, a sitting posture in this case. If we want to do a desired activity, like run a marathon, for example, we typically need to train. If we spend many hours running every day, maintaining that one posture will affect our body. Some muscles will get tighter, making it easier to run long distances or run faster. But it will also make it harder to do other things, like reach into a deep forward fold in yoga. When we electively choose an activity, we probably accept its pros and cons. However, we likely haven’t thought much about how best to train our body to sit. ## Ideal sitting posture Can we sit better? The answer seems to be yes. The effects of being sedentary for long stretches, associated with prolonged sitting, may remain. However, anatomically, it seems that we can sit better and reduce some of the problems associated with sitting posture. [Tom Myers of Anatomy Trains](https://www.anatomytrains.com/) describes proper balance in sitting as maintaining an appropriate amount of the lordotic and kyphotic curves that should appear in our [spine](https://3dmusclelab.com/exploring-the-spine/), and give it some of its strength and resiliency. Ideally, there is a balance between the tissues on the front and [back of our body](https://3dmusclelab.com/erector-spinae-muscles/), holding us up. We can look for that balance in sitting posture by establishing our pelvic base on the anterior part of our ischial tuberosities. Several references suggest that we aim for an angle of 135 degrees between the thigh and spine when sitting on the edge of a chair or a stool. Then, with your spine in extension, stack the torso, head, and neck comfortably over one another. Optimally, our torso, head, and neck are not significantly in front of or behind the acetabulum of the hip joints. Arranging our body with this orientation and relationship lets gravity help us keep these heavy parts of our body resting over one another. ## Reducing the negative effects of sitting The obvious way to reduce the negative effects of sitting is to sit less. But we don’t always have a choice about how much we have to sit, especially in our work environments. So, the next best option is twofold. First, take frequent breaks from sitting during the day. Interrupt your time sitting as frequently as is practical by getting up to [stretch](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/), take a walk, or work from a different position. If sit-stand work stations are available in your work space, that’s one option for breaking up the long stretches of sitting and varying your position. Finally, when you do sit, practice using a more anatomically ideal sitting posture. ## Conclusion Many of us have to sit for hours every day, and often, some of the sitting we do is not optional. We may have little choice about how long we sit at work, for example. But we do have control over how we sit, and we can incorporate more frequent breaks to interrupt longer stretches of sitting. Incorporating just these two changes can help reduce the negative impacts of sitting posture. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 4: The Close Environment. In Clinical Application of Neuromuscular Techniques – The Lower Body. Volume 2 (Second Edition). New York, NY: Churchill Livingstone Publishing. [Cho, M., J.S. Han, S. Kang, et al. 2023. Biomechanical effects of different sitting postures and physiologic movements on the lumbar spine: A finite element study. Bioengineering (Basel). 10(9):1051.](https://pmc.ncbi.nlm.nih.gov/articles/PMC10525568/) [Kallings, L.V., V. Blom, B. Ekblom, et al. 2021. Workplace sitting is associated with self-reported general health and back/neck pain: a cross-sectional analysis in 44,978 employees. BMC Public Health. 21(1):875.](https://pubmed.ncbi.nlm.nih.gov/33957889/) [Lurati, A.R. 2018. Health issues and injury risks associated with prolonged sitting and sedentary lifestyles. Workplace Health Saf. 66(6):285-290.](https://pubmed.ncbi.nlm.nih.gov/29251259/) Myers, T. W. 2014. Chapter 10: Anatomy Trains in Training. In: Anatomy Trains. (New York: Churchill Livingstone). p.224-225. [Ten Broeke P., B. Gardner, D.G.J. Beckers, S.A.E. Geurts, and E. Bijleveld. 2023. Why do people sit? A framework for targeted behavior change. Health Psychol Rev. 17(4):641-654.](https://pubmed.ncbi.nlm.nih.gov/36343923/) --- Source: https://3dmusclelab.com/anatomical-terms-for-movements/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Anatomical Terms For Movements ![Anatomical Terms for Movement](https://3dmusclelab.com/wp-content/uploads/2024/11/anatomical-terms-1.jpg) An essential part of [learning](https://3dmusclelab.com/whats-your-learning-style/) and [studying kinesiology](https://3dmusclelab.com/5-tips-for-learning-kinesiology/) is being able to communicate about it. Similarly to what I discussed in my last article about the [anatomical terms we use for location](https://3dmusclelab.com/anatomical-terms-location-position/) in the body, we also have anatomical terminology for movement. In this article, we’ll explore the language we use to clearly describe different types of movements in the body. ## Basic movements In the world of anatomy and [kinesiology](https://3dmusclelab.com/what-is-kinesiology/), we have terms for basic movements that occur at multiple joints. We also have specialized terms for very specific movements that occur only at individual unique joints. Let’s start our tour of anatomical terms for movement with the basic movements that take us out of and return us to [anatomical position](https://3dmusclelab.com/anatomical-position/). You’re probably familiar with many of these already. ### Flexion and extension We use the terms flexion and extension to describe movement at several joints like the [knee](https://3dmusclelab.com/knee-joint/), hip, [elbow](https://3dmusclelab.com/elbow-and-forearm-in-movement/), [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/), and others. Most generally, the term flexion means a movement that reduces the angle of a joint. For example, if I flex my [elbow joint](https://3dmusclelab.com/elbow-joint-and-forearm/), I bring my forearm closer to my upper arm. That action decreases the angle of the [elbow joint](https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/). The term extension refers to the opposite. Extension describes a movement that increases the angle of a joint. If I extend my [knee joint](https://3dmusclelab.com/knee-hyperextension/), my lower leg moves farther away from my thigh. That action increases the angle of the knee joint. Flexion and extension are movements that happen in the [sagittal plane](https://3dmusclelab.com/planes-of-movement/). ### Other types of flexion We also have some variations on the term flexion that describe specialized movements that only occur at specific [joints](https://3dmusclelab.com/synovial-joint/). Lateral flexion is the anatomical term that we use to describe side bending. That movement happens in the frontal or coronal plane. It is used to describe side bending of our [spine](https://3dmusclelab.com/exploring-the-spine/) in the torso or the lateral bending of our head on our neck. Dorsiflexion and plantarflexion describe movements of the foot that happen at the ankle joint. If you plantar flex your ankle, you take your toes farther away from the front of your foreleg. Colloquially, we refer to this as “pointing our toes.” If you dorsiflex your ankle, you bring your toes closer to the front of your foreleg. The term dorsiflexion is also used along with the term palmarflexion to describe movements of the hand at the wrist. When we use the term dorsiflexion to describe wrist movement, we are referring to the movement at the wrist that brings the back of our hand closer to our forearm. Palmarflexion, as it’s name suggests, is the term for wrist movement that brings the palm side of our hand closer to our forearm. We can also use the more general terms flexion and extension to describe the movement of the hand at the wrist in the sagittal plane. But, you will sometimes see these more specific terms used, so it’s helpful to understand what they refer to. ### Adduction and abduction Adduction and abduction describe movements that happen at many joints in the frontal or coronal plane. Adduction is a movement that brings a structure closer to the midline of our body. Abduction is the opposite. If we abduct a structure, we move it farther from the midline of our body. If you lie on your back to make a snow angel in the winter, you are abducting your arms and legs when you take them away from you. You are adducting your arms and legs when you bring them back into your body. We are most familiar with adduction and abduction movements that happen at our [shoulder](https://3dmusclelab.com/shoulder-girdle/) and [hip joints](https://3dmusclelab.com/exploring-the-hip-joint/), but there are other joints in the body where these movements happen such as some of the small joints we use to move our fingers toward and away from each other. ### Other types of adduction Horizontal adduction is also sometimes referred to as horizontal flexion. It is a movement in the transverse or horizontal plane. It’s usually used to describe the action at the shoulder joint when our arm is already in a flexed position and we bring it closer to the midline horizontally. ### Rotation Rotation is the anatomical term for turning a structure around an axis in the transverse or horizontal plane. You are probably most familiar with the rotation that we do at the two ball and socket joints in our body, the hip and the shoulder joints. In addition to movement at our ball and socket joints, we can also use the anatomical term rotation to describe turning our head on our neck or twisting our spine. We can use more specific terms to describe the direction of rotation. Medial rotation, also called internal rotation, is the anatomical term used to describe rotating our leg or our arm toward the midline of our body. Lateral rotation describes the opposite movement. Lateral rotation, also referred to as external rotation, describes a rotational movement away from the midline of our body. ### Special types of rotation In addition to the general anatomical term rotation, we have some specific terms for particular types of rotation. Circumduction is a special type of rotation that combines flexion/extension with abduction and adduction movements to move a limb in a circle at a ball and socket joint. If we move our arm in a circle through what we might think of as its full range of motion, that is circumduction. Pronation and supination are anatomical terms specifically used to describe the rotation of the forearm at the radioulnar joints. When we rotate our forearm in the direction that brings our palm up, that is supination. When we rotate our forearm in the opposite direction which brings our palm down, that is pronation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Anatomical terms for specialized movements Throughout our body, we have examples of uniquely constructed joints that require specialized movements. Many of those movements have a name. While there are too many examples to include every one of these specialized movement terms here, I have included a few of the more common ones that you are more likely to encounter. ### Elevation and depression The anatomical terms for movement, elevation and depression, are used to describe movements of the [scapula](https://3dmusclelab.com/scapula/) as well as [the jaw](https://3dmusclelab.com/jaw-muscles/). When we draw our scapulae or our mandible down, that is called depression. The opposite, when we lift a scapula or our jaw, is called elevation. ### Inversion and eversion Inversion and eversion are anatomical terms for movement that happens at the [ankle joint](https://3dmusclelab.com/exploring-the-ankle-joint/), specifically the subtalar joint. Inversion and eversion are side-to-side movements that happen in the frontal plane. In eversion, we are bringing the top of our foot closer to the midline of the body. When we do inversion, we are bringing the top of the foot farther away from the body. ### Radial and ulnar deviation Deviation is a specialized movement that happens only at the [wrist joint](https://3dmusclelab.com/hand-and-wrist-anatomy/). This side-to-side movement at our wrist is a variation on abduction and adduction. Deviation happens when the carpal bones move relative to the radius (one of the two forearm bones). Sideways movement at the wrist toward the thumb side is called radial deviation. Sideways movement at the wrist toward the pinky side is called ulnar deviation. ### Protraction and retraction Like elevation and depression, protraction and retraction are anatomical terms used to describe the movement of the scapulae and the mandible. The term retraction describes the movement of bringing either a scapula or the jaw more posterior, closer to the back of our body. With respect to the scapulae, retraction would bring them closer to the spine. Protraction is the term for drawing either the scapulae or the mandible forward. ## Conclusion Our bodies are complex, with an array of unique movements that allow us to do everything from shrug our [shoulders](https://www.yoganatomy.com/shoulder-pain-injury-in-yoga/) to drive a car. Describing and communicating this complexity of movement requires a shared language. Anatomical terms for movement help us clearly communicate what and how we’re observing movement in the body. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/teaching-pilates-aids-musculoskeletal/ Author: David Keil · Updated: 2026-09-08 Anatomical Applications # Kinesiology Applied: Teaching Pilates Aids In Managing Musculoskeletal Conditions ![Teaching Pilates aids musculoskeletal conditions](https://3dmusclelab.com/wp-content/uploads/2025/03/pilates-teacher-training.jpg) Why learn anatomy and kinesiology? How does that knowledge come into play in real-world applications? Learning [how our body moves](https://3dmusclelab.com/functional-movement/) through the lens of [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) can help us understand what’s happening with our clients and students whether we’re teaching Pilates, yoga, working with personal training clients, or massage therapy clients. If you run a Pilates teacher training and need to cover this material with your trainees, we license our [anatomy for Pilates teacher training programs](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) to programs in the US, Mexico, Germany and Australia. In this series of articles, we’ll take a look at some of the many ways we apply kinesiology knowledge in sports, training, and physical activities. We’ll share interesting research that shows how important an [understanding of kinesiology](https://3dmusclelab.com/5-tips-for-learning-kinesiology/) is to a particular movement discipline, body therapy, or sport. In this article, we look at research showing how teaching Pilates exercises supports managing chronic musculoskeletal conditions. ## Background Older adults can be challenged to stay physically fit. Chronic musculoskeletal conditions like low back pain, [knee](https://3dmusclelab.com/knee-joint/) pain, and osteoarthritis can make it uncomfortable or painful to be active. Those kinds of chronic conditions can negatively impact physical function in day-to-day life as well as have negative psychological effects. Reducing physical activity makes it more likely that chronic [musculoskeletal](https://3dmusclelab.com/muscle-contractions/) conditions will arise. Starting and maintaining physical activity when we’re younger can help slow that circle of decline. However, once we reach middle age and older, the chance of experiencing some kind of chronic musculoskeletal condition increases. So, what kind of movement activities are appropriate for older adults with these conditions? The research team on the study we summarized here was interested in how Pilates affects people in that group. Pilates is a low-intensity movement practice that improves endurance, balance, and strength by training the body to initiate movement from the core [musculature](https://3dmusclelab.com/what-is-a-muscle/). Pilates is popular among a variety of populations from dancers looking to build core stability to older folks wanting to maintain strength, [flexibility](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/), and balance as they age. The researchers who conducted the study we have summarized chose to do a review study to investigate how teaching Pilates exercises to older adults with chronic musculoskeletal issues affects those conditions. A review study is a type of scientific study that collectively examines the results of many smaller studies on the same topic. By combining the results of many smaller studies, scientists can potentially see larger patterns that weren’t clear from the smaller individual studies. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Research question in the study Is Pilates helpful in managing chronic musculoskeletal conditions in older adults? ## Summary of methods The researchers who conducted this review study found the individual smaller studies that they included by doing a thorough database search of research published in peer-reviewed journals and research available from other types of publications. They used these database search tools: Cochrane Controlled Register of Trials, Cumulative Index of Nursing and Allied Health Literature, Google Scholar, PsycInfo, Pubmed, SCOPUS, Web of Science, Opengrey, and Worldcat. After they found all the studies that examined Pilates’ effects on musculoskeletal conditions, they conducted screenings to determine the scientific quality of each study. Then, they performed data extraction to calculate the effects of each Pilates intervention in the studies included in the review. The individual studies that the researchers included in their review study looked at the effects of Pilates on populations with back pain, osteoporosis, chronic [neck](https://3dmusclelab.com/the-deep-neck-muscles/) pain, and [knee](https://3dmusclelab.com/knee-hyperextension/) osteoarthritis. The participants across all of those individual studies combined had a mean age of 56.68 years old and 73% of them were female. The Pilates interventions in each of the individual studies the researchers included in their larger review were 60 minutes long. The frequency of how often participants were asked to complete Pilates exercises ranged from one to five times per week across each of the individual studies. The duration of each of those studies ranged from 10 days to one year. ## Summary of key findings Pilates reduced pain and disability in participants experiencing all chronic conditions evaluated ([low back pain](https://www.yoganatomy.com/low-back-pain-in-yoga-practice/), osteoporosis, neck pain, and knee osteoarthritis) compared to control groups. Additionally, teaching Pilates exercises improved physical functioning in participants with low back pain, osteoporosis, [neck](https://3dmusclelab.com/neck-muscles-superficial/) pain, and [knee](https://3dmusclelab.com/valgus-and-varus-knee-pain/) osteoarthritis compared to control groups. Quality of life also improved in those with low back pain and osteoporosis when they did Pilates exercises compared to control groups. (Quality of life wasn’t measured in the studies evaluating the other conditions.) ## Kinesiology application This review study shares some exciting findings that teaching Pilates exercises can positively influence several types of chronic issues for older adults. One of the important things about Pilates that makes it impactful, is how precise and specific each exercise is. You can imagine then, that teaching Pilates well, requires sufficient knowledge of anatomy and kinesiology. When it comes to working with special populations, like older adults experiencing chronic conditions and pain, understanding kinesiology and how to apply it in movement is even more important for Pilates teachers. ## Conclusion Pilates exercises positively affected older adults with musculoskeletal conditions including back pain, osteoporosis, chronic neck pain, and knee osteoarthritis. The Pilates interventions reduced pain, and improved functional movement and overall quality of life. Kinesiology knowledge was essential for finding the right Pilates approach for each of the populations evaluated in the studies included in the larger review. If you teach Pilates, teach yoga, offer personal training, or provide massage therapy, kinesiology knowledge can help take your skills to the next level. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## Reference [Denham-Jones, L., L. Gaskell, N. Spence, and T. Pigott. 2022. A systematic review of the effectiveness of Pilates on pain, disability, physical function, and quality of life in older adults with chronic musculoskeletal conditions. Musculoskeletal Care. 20(1):10-30.](https://pubmed.ncbi.nlm.nih.gov/34028164/) --- Source: https://3dmusclelab.com/palpating-your-iliopsoas-muscle/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Palpating Your Iliopsoas: Why? ![Palpating Your Iliopsoas Muscle](https://3dmusclelab.com/wp-content/uploads/2019/01/psoas-muscle-contact.jpg) As we noted in our previous article on [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/), this is a key postural muscle. Iliopsoas is a particularly important muscle, both with regard to its function and its dysfunction. Its activity can also feel subtle and difficult to detect in our body. As the iliopsoas is located deep in the body, it can be difficult to visualize just where this muscle is and how it relates spatially to other muscles and bony structures. Sometimes the felt sense is the best way to really understand where something is in the body, especially when it’s hard to see. So one way that we can add to your understanding of just where these core muscles are is by palpating your iliopsoas. Palpation, is a technical word for touch. You could think of it as touch with the purpose of gathering information. Massage therapists, osteopaths, physical therapists, chiropractors, and other professionals all use palpation in their work. Palpation can help those professionals locate bony landmarks and muscles in a client’s body. It can also help them determine that condition of a muscle or tissue. For example, palpation can help them determine if a muscle is engaged or relaxed. In your own body, palpation can help you locate muscles and bones too! So, let’s dive into palpating your iliopsoas. ## Cautions before palpating your iliopsoas Both the iliacus and the psoas major portions of the iliopsoas are core structures in our body. This means we have to reach through or around other structures in order to feel them. In this case we’ll be palpating your iliopsoas through your abdominals and just below many organs. For that reason, DO NOT try this exercise for palpating your iliopsoas if: - You’re pregnant. - You have any issues, dysfunction, or pain in the abdominal area, such as (but not limited to): colitis, constipation, or kidney disorders. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Finding iliopsoas Remember that iliopsoas actually refers to two muscles: [iliacus and psoas major](https://3dmusclelab.com/iliopsoas-muscle-anatomy/). Iliacus is the deep hip flexor that’s found along the inside of the ilium. Psoas major is the key core muscle that runs along your lumbar spine, continues over the front of the hip joint, and joins up with iliacus to attach to the lesser trochanter of the femur. We’ll be palpating each muscle of your iliopsoas separately. ### The set up Have a seat on the floor with your legs straight out in front of you. Let the legs relax and roll outwards, and let a little bend come into the knees. Fold forward at the hips a little and let the abdomen relax as you do so. ### Iliacus Bring each hand to find your hip points – the bony protrusions on the front of your pelvis, anatomically referred to as the anterior superior iliac spine (ASIS). Curl your fingers around the hip points toward the inside of the pelvic bowl and let them sink in about an inch. Press your fingers outward towards the bone from the inside of the pelvic bowl and then lift one leg. The tissues you feel contracting on each side of the body are the two iliacus muscles. ### Psoas major Keep your fingers at the same depth in your tissue, but change their direction. Move the direction of your fingers toward the spine. Again, lift one leg. You should feel a distinct band of tissue pushing up into your fingers. This is psoas major. ## Learn more about iliopsoas Now that you have a felt sense of where the two muscles that make up iliopsoas are located in the body, by palpating your iliopsoas, read more and explore how the [iliopsoas is involved in movement](https://3dmusclelab.com/iliopsoas-and-movement/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## Resources [Earls, J. and T. Myers. 2017. Chapter 6: The Hip. *In* Fascial Release for Structural Balance. Berkley, CA. North Atlantic Books.](https://bookshop.org/p/books/fascial-release-for-structural-balance-revised-edition-putting-the-theory-of-anatomy-trains-into-practice-thomas-myers/9560497?ean=9781623171001&gclid=CjwKCAjw69moBhBgEiwAUFCx2OhrF3m5iKZNz6V5BoBRHO4PAZ2NUckDNI_hGFjQWgpqm8hpMvUGvhoC1B0QAvD_BwE) --- Source: https://3dmusclelab.com/shoulder-joint-in-movement/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Let’s Break Down Some Real-life Shoulder Movements ![The Shoulder In Movement](https://3dmusclelab.com/wp-content/uploads/2019/11/shoulder-tennis.jpg) In the previous article, [What Is The Shoulder Girdle](https://3dmusclelab.com/shoulder-girdle/), we looked at the bones, joints, and basic movements of the shoulder girdle. But this only tells us so much about what’s happening at the shoulder joint in real-life movement. In this article we’ll cover what muscles attach to and move the shoulder joint, and we’ll apply that information to understanding movements of the shoulder in some daily life activities and common sports. To review: the shoulder joint is the ball and socket joint where the humerus (the upper arm bone) meets the depression in the scapula called the glenoid fossa. Its anatomical name is the glenohumeral joint. There are nine muscles that cross the glenohumeral joint, including: - Biceps brachii (long head) - Triceps brachii (long head) - Deltoid - Supraspinatus - Infraspinatus - Teres minor - Subscapularis - Teres major - Coracobrachialis There are a couple of other muscles that attach to and move the humerus, but don’t attach to the scapula, so they don’t technically cross the glenohumeral joint. However, they still contribute to moving the arm as part of the larger [shoulder complex](https://3dmusclelab.com/shoulder-girdle/). (Remember the whole shoulder complex includes muscles that go from the humerus to the scapula AND the muscles that go from the humerus to the clavicle and cross the acromioclavicular joint.) So, we could also include the following muscles in the group that move the shoulder joint: - Pectoralis major - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) If we group the muscles that move the shoulder by action we would have the following lists: Flexion of the shoulder: - Biceps brachii - Deltoid (anterior fibers) - Pectoralis major Extension of the shoulder: - Triceps brachii (long head) - Deltoid (posterior fibers) - [Teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - Teres minor - Infraspinatus Adduction of the shoulder: - Biceps brachii (short head) - Triceps brachii (long head) - [Teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - Pectoralis major Abduction of the shoulder: - Deltoid - Supraspinatus Medial rotation of the shoulder: - Deltoid (anterior fibers) - Teres major - Latissimus dorsi - Pectoralis major - Subscapularis Lateral rotation of the shoulder: - Deltoid (posterior fibers) - Teres minor - Infraspinatus ## Shoulder movements in daily life So, now that we’ve reviewed the movements of the glenohumeral joint and the muscles that move the humerus, let’s apply our knowledge to a few situations from daily life. Remember though, as we highlight what the shoulder joint is doing in a particular activity, that real-life actions are complex and are almost always a combination of multiple actions at more than one joint. If you were closing a door by pulling it towards you, then you would be extending the shoulder joint. The muscles involved would include: triceps long head, deltoid (posterior fibers), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), and teres minor. If you were opening a door by pushing it away from you, then you would be flexing the shoulder joint. The muscles involved would include: biceps brachii, deltoid (anterior fibers), and pectoralis major ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Shoulder movements in sports Now let’s take a look at a couple of actions in tennis and some weight-lifting exercises you might do in the gym. If you were doing a forehand stroke with your racket in tennis, you would be doing horizontal flexion (also called horizontal adduction) and medial rotation at the shoulder. The muscles involved would include: pectoralis major, [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), subscapularis, and deltoid (anterior fibers). If you were doing a backhand swing with your racket in tennis, you would be doing horizontal extension (also called horizontal abduction) and lateral rotation at the shoulder joint. The muscles involved would include: teres minor, infraspinatus, and deltoid (posterior fibers). If you were watching shoulder movements in the gym, you might see lateral movements like abduction and adduction. If you did a dumbbell lateral raise, you would be abducting your arm at the shoulder. That is, you would raise your arm with the dumbbell laterally to 90 degrees. The muscles involved would include the deltoids and supraspinatus at the start of the movement. If you did a wide-grip pull-up you would be adducting your arms at the shoulder joints to pull yourself up to the bar. The muscles involved would include primarily: triceps brachii (long head), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), and pectoralis major. As you look at shoulder movements in real-life actions you get an idea of how complex movement really is. If you want to challenge yourself to start applying anatomy, try this process for yourself. Take some real-life movements and see if you can break them down into their anatomical movements. Do you want to learn more about the shoulder? Check out our previous post, [What Is The Shoulder Girdle](https://3dmusclelab.com/shoulder-girdle/)? The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/trapezius-computer-posture/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Why Does My Neck Hurt When Sitting At The Computer? ![Trapezius Muscle During Computer Posture](https://3dmusclelab.com/wp-content/uploads/2020/01/desk-posture.jpg) These days, just about everyone spends some time at the computer each day. Along with all that time in front of the computer we might experience the seemingly ubiquitous tension on the back of the neck and shoulders. One culprit which can contribute to that tension and neck pain is the upper portion of the [trapezius muscle](https://3dmusclelab.com/trapezius-muscle/) (Amin et al., 2018; Ghaderi et al., 2019; Kelson et al., 2019). ## Where is the upper trapezius? Remember that [the trapezius](https://3dmusclelab.com/trapezius-muscle/) can, in a way, be considered to be three different muscles because it has three main sections which each have fibers running in a different direction from the other sections. It’s the upper portion of this muscle that we are most interested in here. This muscle attaches from the nuchal ligament, base of the occiput, and spinous processes of vertebrae C1-C7 to the lateral third of the clavicle and the acromion process. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What does the upper trapezius do? The upper trapezius can upwardly rotate and [elevate the scapula](https://3dmusclelab.com/scapula/). While the attachments at the nuchal ligament, occiput and cervical vertebrae are usually considered the origin, remember that muscle origin and insertion are simply a convenient way to organize what we know about a muscle’s attachments. Muscles can create movement in either direction depending on the circumstances. If we keep in mind the attachments of the upper portion of this muscle, then we could imagine that it could also contribute to extension of the head and neck. ## How are the upper traps involved in our computer posture? Let’s think for a moment about what movements the upper trapezius is contributing to when we sit at a computer. In this case, it’s the extension of the head and neck that it contributes to which is particularly relevant. When we sit at a computer, the upper portions of this muscle can shorten the back of the neck which shortens the distance between the head and the scapulae. In the case of sitting at a computer, we typically take our head forward and the upper trapezius has to resist that position by pulling the head back and shortening. Essentially, it’s regularly stabilizing the head and neck in a forward head position. Researchers have found that the upper [trapezius](https://3dmusclelab.com/trapezius-muscle/) is highly active when holding our shoulders, head, and neck in a posture typical of sitting at the computer (Bodin et al., 2019). The activity level of this muscle when sitting at a computer was even higher than when using a smartphone (Bodin et al., 2019). EMG studies also show that it is active when flexing and abducting the arm (Travel and Simons, 1993) as we might be doing when using a mouse at the computer. The chronic shortening and over-use of the upper trapezius in this way can potentially contribute to neck pain (Amin et al., 2018; Ghaderi et al., 2019; Kelson et al., 2019) and trigger points (Travel and Simons, 1993). In fact, Travel and Simons, 1993, note that the this muscle is the most common muscle in the body to present with active trigger points, which can refer pain to the neck and even the jaw. ## What to do at the computer? One research team found that eccentric exercises for the upper trapezius reduced neck pain (Heredia-Rizo et al., 2019), however, the most common recommendation from those who specialize in ergonomics and workplace health is simply to get up and move. Get up from the computer and change your posture frequently, at least every hour (Keown et al., 2018) and even as much as every 20 minutes (Amin et al., 2018). If you spend regular time in front of the computer, do your trapezius a favor — get up frequently, move around, and stretch to reduce neck pain. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Amin, I., A. Arshad, A. Rabia. 2018. An observational research to assess the onset of neck pain among various computer users working for various time durations on different types of computers. Indo American Journal of Pharmaceutical Sciences. 5(12):13956-13961.](http://www.iajps.com/pdf/december2018/68.IAJPS68122018.pdf) [Bodin, T., K. Berglund, M. Forsman. 2019. Activity in neck-shoulder and lower arm muscles during computer and smartphone work. International Journal of Industrial Ergonomics. 74:102870.](https://www.sciencedirect.com/science/article/abs/pii/S0169814118303500?dgcid=rss_sd_all) [Ghaderi, F., K. Javanshir, M. Asghari Jafarabadi, A. Nodehi Moghadam, and A. Masoud Arab. 2019. Chronic neck pain and muscle activation characteristics of the shoulder complex. Journal of Bodywork and Movement Therapies. 23:913-917.](https://www.ncbi.nlm.nih.gov/pubmed/31733782) [Heredia-Rizo, A.M., Petersen, K.K., Pascal, M., Arendt-Nielsen, L. 2019. Clinical outcomes and central pain mechanisms are improved after upper trapezius eccentric training in female computer users with chronic neck/shoulder pain. The Clinical Journal of Pain. 35(1):65-76.](https://www.ncbi.nlm.nih.gov/pubmed/30222615) [Kelson, D.M., S.E. Mathiassen, D. Srinivasan. 2019. Trapezius muscle activity variation during computer work performed by individuals with and without neck-shoulder pain. Applied Ergonomics. 81:102908.](https://www.ncbi.nlm.nih.gov/pubmed/31422258) [Keown, G.A., M. Chiro, and P.A. Tuchin. 2019. Workplace factors associated with neck pain experienced by computer users: A systematic review. Journal of Manipulative and Physiological Therapeutics. 41(6):508-529.](https://www.ncbi.nlm.nih.gov/pubmed/30025880) Travell, J.G. and D.G. Simons. 1993. Trapezius Muscle. *In* Myofascial Pain and Dysfunction —The Trigger Point Manual. Volume 1. --- Source: https://3dmusclelab.com/anatomical-terms-location-position/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Understanding Anatomical Terms For Location And Relative Position ![Anatomical Terms For Body Location And Relative Position](https://3dmusclelab.com/wp-content/uploads/2024/10/anatomical-terms.jpg) If you work with students or clients in a body-centered practice like yoga, Pilates, physical therapy, or personal training, then you know how important it is to be able to communicate about what you see and feel in someone’s body. For that reason, anatomists, medical practitioners, and others have developed a shared anatomical language to describe the location and relative position of structures in the body. This terminology helps us be specific and consistent about what we’re describing. Bodies are complicated. Using agreed upon anatomical terms helps us be clear in our communication about the complexity we’re describing. In this article, I’ll take you on a tour of the anatomical terms used to describe the location and relative position of structures in the body. ## Describing position and location in the body When we use positional anatomical terms, we commonly use them in one of two ways. We might refer to something in the body by its general location, for example on the front of the body. The other way we reference structures in the body is by describing their position relative to something else. For example, we might refer to a muscle as being above, below, underneath, or on top of another muscle. Keep that in mind as we walk through common anatomical terms for position and how we often use them. Additionally, sometimes there is more than one set of anatomical terms to describe particular positions and locations. Where there is more than one set of terms for a position in the body, we’ll discuss both. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Anatomical terms for position and location ### Superior and inferior The first set of terms we’ll discuss are anatomical terms for structures that are above or below another structure. We have two sets of terms we can use to describe parts of the body that are above or below something else. The term superior refers to something that is above something else. Inferior means that something is below something else. ### Cranial and caudal We have a second set of anatomical terms that aren’t used quite as often but have a similar meaning to superior and inferior. We can also use the terms cranial and caudal to describe the relative position of structures that are above or below something in the body. Something that is cranial means it is toward the head compared to another structure. Something that is caudal means it is towards your “tail,” or away from your head, which in the case of a human in anatomical position would be closer to your feet. Because we are describing the location of structures from [anatomical position](https://3dmusclelab.com/anatomical-position/), something that is above something else would also be closer to the head. A structure that is below another structure would also be closer to the feet. If we know the roots of these anatomical words, the meanings of the roots of these words can help us potentially understand and remember the anatomical terms. Cranial is related to the word cranium which you probably already know refers to the skull. So it makes sense that something that is in the cranial direction is something closer to the skull or head. Caudal is related to the word cauda which means tail. So, likewise, it makes sense that something that is in the caudal direction is closer to the tail. ### Lateral and medial The next set of anatomical terms we’ll look at involve describing the position of structures in relation to the midline of the body. If we draw a line from the top of our head to our feet that bisects the body into a right and left side in the [sagittal plane](https://3dmusclelab.com/planes-of-movement/), that is referred to as the midline of the body. Something that is closer to that midline positionally is referred to as more medial. Something farther from that midline or closer to the outside of the body is referred to as more lateral. ### Internal and external The terms internal and external are similar to the terms lateral and medial. The terms internal and external are used interchangeably with lateral and medial when we are describing a direction of movement. Movement such as rotation in the medial direction, describes movement that is going internally, or closer to the midline (inside) of the body. Movement in a lateral direction is movement externally, away from the center of the body, or towards the outside of the body. However, when we refer to a position of a structure, rather than a movement, we typically use the words lateral and medial. ### Anterior, posterior, ventral, and dorsal If we divide our body into a front and back half in the coronal plane, this is where we apply the anatomical terms anterior and posterior. A structure that is more anterior is closer to the front of the body. Something that is more posterior is closer to the back of the body. Additionally, there is another set of terms that are used similarly to anterior and posterior, but are used less often. Those terms are ventral and dorsal. Ventral, like the term anterior, is used to refer to a structure that is on the front of the body. Dorsal is similar to posterior and refers to a structure that is on the back of the body. ### Distal and proximal The next two terms, distal and proximal, are primarily used to describe only the relative position of structures on the appendicular skeleton in relation to their distance from the axial skeleton. Remember that the appendicular skeleton includes arms, legs, [shoulder girdle](https://3dmusclelab.com/shoulder-girdle/), and [pelvic girdle](https://3dmusclelab.com/exploring-the-pelvis/). The rest of your skeleton, including the [spine](https://3dmusclelab.com/exploring-the-spine/), ribcage, head, and [neck](https://3dmusclelab.com/neck-muscles-superficial/), is considered the axial skeleton. Distal is used to describe a structure on the appendicular skeleton that is farther away from the axial skeleton than something else (on the appendicular skeletal system). The term proximal is used to describe a structure that is closer to the axial skeleton than something else (on the appendicular skeletal system). For example, we could say that our fingers are distal to our elbow because they are farther away from the rest of our body (our axial skeleton) than our elbow. ### Ipsilateral and contralateral Ipsilateral and contralateral are two frequently confused words for the position of body structures. If we break down the roots of these two words it can help us understand their meaning. The prefix “ipsi” means the same. The prefix “contra” means opposite or against. Lateral means the side of something. So these are anatomical terms that describe whether something is located on, or happening on, the same side or opposite side as something else. These words can be used to describe relative position in the body or relative [movement](https://3dmusclelab.com/functional-movement/). For example, I could say my internal oblique muscles run from my iliac crest and inguinal ligament to my ipsilateral lower ribs because the [internal oblique muscle](https://3dmusclelab.com/abdominal-muscles/) travels between these attachments on the same side of the body. If I’m using these words to describe movement, I could say that when we walk, as we step with the right foot, our contralateral arm swings forward at the same time. We would use the word contralateral to describe that [movement in gait](https://3dmusclelab.com/what-is-the-gait-cycle/) because it is our opposite arm that swings forward when we take a step. ### Superficial and deep The anatomical terms superficial and deep describe the depth at which something is found in the body. Another way to say that is that these terms describe how close to the surface of the body something is relative to something else. Superficial refers to a structure that is closer to the surface of the body. Deep refers to a structure that is farther away from the body’s surface. For example, I could say my skin is superficial to my biceps brachii muscle. Or, I could compare the depth of two [muscles](https://3dmusclelab.com/what-is-a-muscle/). For example, the [brachialis muscle](https://www.yoganatomy.com/the-brachialis-muscle/) is deep to (underneath) the [biceps brachii muscle](https://3dmusclelab.com/elbow-and-forearm-in-movement/). ### Supine and prone The terms supine and prone are a little different from the terms I’ve explained so far. These two terms describe the position of the whole body in space. Supine is the anatomical term to describe lying face up. Prone is the anatomical term to describe lying face down. ## Conclusion The body is complex. An important part of learning about the body including the study of [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) is being able to communicate clearly what we see. Anatomical terms help us do that. Anatomical terms for position help us use precise language to describe where structures are located in the body and how they are positioned in relation to the front, back, top, bottom, inside, and outside of the body, as well as how they are positioned in relation to other structures. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscle-strengthening/ Author: David Keil · Updated: 2026-06-20 Anatomical Applications # What Do We Mean By Muscle Strengthening? ![Muscle Strengthening](https://3dmusclelab.com/wp-content/uploads/2026/06/muscle-strengthening.jpg) Muscle strengthening is a big topic in the media these days, and it’s not just for bodybuilders anymore. The importance of building and maintaining muscle strength has been emphasized for athletes, [older folks](https://3dmusclelab.com/muscles-when-we-age/), people recovering from [injuries](https://3dmusclelab.com/ankle-sprain/), women, and many other populations. But what do we mean when we say [muscle](https://3dmusclelab.com/what-is-a-muscle/) strengthening? In this article, we’ll take a look at what muscle strengthening is, what happens when we strengthen muscle tissue, and what some of the benefits are. ## What is muscle contraction? Depending on our particular context, when we say muscle strengthening, we probably think of lifting weights at the gym. Lifting weights is one type of strength training. But it’s not the only kind of muscle strength, because shortening to contract is not the only type of muscle action. Let’s start with the basics and briefly review skeletal [muscle contractions](https://3dmusclelab.com/muscle-contractions/). Remember that muscles don’t just contract and shorten. Muscles can act in several different ways. When a muscle shortens when we contract it, that’s called a concentric contraction. A muscle can also lengthen during a contraction. That’s called an eccentric contraction. Finally, we can contract a muscle in situations where it doesn’t change length at all. That’s called an isometric contraction. If we’re thinking about muscle strength, concentric muscle contractions are what happen when we lift a dumbbell at the gym to do a [bicep](https://3dmusclelab.com/biceps-and-triceps/) curl. Isometric contractions are what your biceps muscles are doing when you hold the dumbbell without moving it anywhere along the way. Eccentric contractions are what your biceps muscles are doing when you slowly lower the dumbbell back down. Each of those situations calls for a different kind of muscle strength. Additionally, there are other, more specific situations where we rely on muscle strength, like the dynamic muscle strength that we need to run up a steep hill, for example. Regardless of the type of contraction, when our [muscles are acting](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/), muscle cells are firing and using up ATP, or energy, at a cellular level, to do work. At a cellular level, when we challenge skeletal muscle tissue by using it, we have a fair idea of what happens. When our nervous system cues a muscle cell to activate through the release of calcium, the individual muscle cell proteins, actin and myosin, are attracted to each other like two magnets. The amount of muscle force is the total of each of the muscle cells that are activating at the same time to do a muscle contraction. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is muscle strengthening? Perhaps surprisingly, however, when we zoom out to a more macro level, our understanding of what happens when we feel stronger or show measurable gains on one or more strength tests is more murky. As with an [increase in flexibility](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/), an increase in strength comes from more than one type of change in our body. Those changes are both in the tissue itself and in our nervous system. Science doesn’t have a complete explanation of exactly what happens physiologically when we have the felt sense that we feel stronger. ### Hypertrophy and muscle strength When we strengthen [muscles](https://3dmusclelab.com/what-is-muscle-fascia/), at least some of the time, hypertrophy occurs. Hypertrophy is the name for an increase in muscle cell size. Increasing tension on our muscles is often correlated with an increase in the size of muscle cells. Interestingly, we can also increase muscle size without increasing strength. The increases we experience in muscle mass are not always correlated with increases in muscle strength. Muscles can increase in size for different reasons. The number of microfibrils can increase, or the fluid volume inside the muscle can increase. An increase in the number of microfibrils is associated with increased strength, but an increase in fluid volume alone is not. ### The nervous system and muscle strength Additionally, when we increase muscle strength in a way that we see an increase in measurements of strength, changes in our nervous system that affect nerve to muscle communication also happen. A recent review paper from 2018 (Suchomel et al., 2018) specifically reported aspects of nerve to muscle communication, including “motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition.” While these actions are more technical than we can cover here, what’s important to understand is that our nervous system also has a role to play in muscle strengthening. ## Applying muscle strength research Although every aspect of muscle strengthening physiology might not be worked out by researchers yet, we do know that the type of resistance training you might already do at the gym or in a fitness class focused on strength-building is effective at building muscle strength. Many research studies agreed, as you might expect, that greater load and frequency led to greater increases in muscle strength. ## Why strengthen our muscles? Although we may not yet have a complete explanation of what happens physiologically when we strengthen our muscles, it’s clear that there are benefits associated with measurable gains in many types of strength. Research found that increased muscle strength was correlated with many aspects of health and wellness, from reductions in diabetes symptoms, decreased obesity, increased longevity, and improved fibromyalgia symptoms, to decreased chances of a cancer diagnosis. All of those are great reasons to keep up with our favorite activities for maintaining muscle strength. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bennie, J.A., D. Lee, A. Khan, G.H. Wiesner, A.E. Bauman, E. Stamatakis, and S.J.H. Biddle. 2018. Muscle-Strengthening exercise among 397,423 U.S. adults: Prevalence, correlates, and associations with health conditions. American Journal of Preventive Medicine. 55 (6): 864-874.](https://www.sciencedirect.com/science/article/abs/pii/S0749379718321378) [Effects of muscle strengthening versus aerobic exercise program in fibromyalgia. 2008. Bircan, C., S.A. Karasel, B. Akgün, O. El, S. Alper. Rheumatol Int 28:527–532.](https://pubmed.ncbi.nlm.nih.gov/17982749/) [Enoka, 1988. Muscle strength and its development: New perspectives. Sports Medicine 6:146-168.](https://pubmed.ncbi.nlm.nih.gov/3055145/) [Foster C. and M.E.G. Armstrong. 2018. What types of physical activities are effective in developing muscle and bone strength and balance? J Frailty Sarcopenia Falls. 3(2):58-65.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7155324/) [Andrews, M. A.W. 2003. Oct. 27. How does exercise make your muscles stronger? Scientific American. Online. Accessed June 10, 2026.](https://www.scientificamerican.com/article/how-does-exercise-make-yo/) [Lopez P., R. Radaelli, D.R. Taaffe, R.U. Newton, D.A. Galvão, G.S. Trajano, J.L. Teodoro, W.J. Kraemer, K. Häkkinen, and R.S. Pinto. 2021. Resistance training load effects on muscle hypertrophy and strength gain: Systematic review and network meta-analysis. Med Sci Sports Exerc. 53(6):1206-1216.](https://pubmed.ncbi.nlm.nih.gov/33433148/) [Mcleod J.C., B.S. Currier, C.V. Lowisz, and S.M. Phillips. 2024. The influence of resistance exercise training prescription variables on skeletal muscle mass, strength, and physical function in healthy adults: An umbrella review. Journal of Sport and Health Science. 13(1): 47-60.](https://pubmed.ncbi.nlm.nih.gov/37385345/) [Reggiani C. and S. Schiaffino. 2020. Muscle hypertrophy and muscle strength: dependent or independent variables? A provocative review. Eur J Transl Myol. 30(3):9311.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7582410/) [Suchomel, T.J., S. Nimphius, and C.R. Bellon, et al. 2018. The importance of muscular strength: Training considerations. Sports Med 48:765–785.](https://link.springer.com/article/10.1007/s40279-018-0862-z) --- Source: https://3dmusclelab.com/ribcage/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # An Exploration Of The Ribcage ![An Exploration of the Ribcage](https://3dmusclelab.com/wp-content/uploads/2025/05/ribcage.jpg) Our ribcage is a critically important structure in our body. Its protective role is likely obvious as it covers some of our vital organs. Our heart and lungs, the organs for two of our most essential functions, breathing and blood circulation, are found in the thorax and protected by our ribcage. But did you know that the ribs are also one of the places where red blood cells are produced in our body? In this article, we’ll explore the structure and function of the ribcage. Keep reading to learn more! ## What structures make up the ribcage? The ribcage makes up the bony container of our thorax, the section of our body above the abdomen, which our shoulder girdle rests on. There are multiple bones and a large number of muscles that cross our thorax at some point. ### Bones Twelve pairs of rib bones come together to create our ribcage. Each rib is composed of a bony section and a cartilaginous section, called the costal cartilage. More specifically, the bony portion of each rib includes several key sections: - Rib head - One or two articular facets - Tubercle - Neck - Costal groove The rib head is the end that connects with the [spine](https://3dmusclelab.com/exploring-the-spine/) and articulates with the vertebrae. The specific places on the rib bone where that connection to the vertebrae happens are called the articular facets. Most of the ribs have two articular facets. However, the first rib only has one. Each rib also has a tubercle, a bony protuberance where the costotransverse [ligament](https://3dmusclelab.com/ligaments-and-tendons/) attaches. The rib neck is the section of the rib between the head and the tubercle. The length of the rib neck varies from rib to rib, and the eleventh and twelfth ribs do not have a neck at all. From the tubercle to the cartilaginous section is the main body of each rib. It’s called the rib shaft. Finally, each rib has a groove present along the bone called the costal groove. This is where the neurovascular bundle runs. #### Types of rib connections While the rib bones share many similarities, there are also a few differences between them. They are often grouped according to those differences. Based on the type of their connection to the sternum, the ribs are often grouped into true ribs, false ribs, and floating ribs. True ribs include ribs one through seven. They’re called true ribs because they connect directly to the sternum via an individual piece of costal cartilage. Ribs eight through ten are called false ribs because their costal cartilage doesn’t connect directly to the sternum. Instead, the costal cartilage for each of these ribs connects to the costal cartilage for rib seven, which then indirectly connects those ribs to the sternum. Finally, ribs eleven and twelve are called floating ribs because they don’t attach to the sternum or any other bone on the ventral side of our body. To form our ribcage, the rib bones attach to the spine on the dorsal (back) side of our body. And, with the exception of the floating ribs, the ribs attach to our sternum on the ventral side of our body. Our sternum has three main sections: the manubrium at the top, the body in the middle, and the small, pointy xiphoid process at the bottom. Ribs one and two attach to the manubrium of the sternum. Ribs three through seven attach to the body of the sternum via their costal cartilage. Ribs eight, nine, and ten attach to a common costal cartilage that then attaches to the costal cartilage of rib seven to indirectly attach these ribs to the body of the sternum. The last two ribs, eleven and twelve, don’t attach to the sternum. Although the spine is not part of the ribcage, per se, it’s where each of the ribs attaches at their posterior end. #### Other important bones Additionally, there are a couple of bones that have a particularly important relationship to the position of the ribcage. Those are the [scapula](https://3dmusclelab.com/scapula/) and the clavicle. The scapula floats in a sea of muscle and connective tissue on the back of the ribcage. It does not have a true articulation with the ribcage, but the position of the ribcage is so influential on scapular position that sometimes that indirect connection is referred to as the scapulothoracic joint. The clavicle is situated just a little superior and superficial to the first rib. It can articulate at a small connection with the first rib. It also articulates with the sternum at the sternoclavicular joint. In that way, movement at the clavicle is indirectly influenced by movement of the ribcage. ### Joints in the ribcage Several important types of joints allow the ribcage to have the kind of movement necessary for it to complete all of its functions. On our back, the ribs articulate with the vertebrae of the spine through costovertebral joints. The costovertebral [joint](https://3dmusclelab.com/synovial-joint/) is where the rib head articulates with the body of a vertebra above, the body of a vertebra below, and the vertebral disc in between those vertebrae. The exception to this is the first rib, which only attaches to one vertebra, T1. On the front side, ribs one through seven articulate with the sternum at joints called sternocostal joints. Additionally, the first rib can articulate with the clavicle at a joint called the [costoclavicular joint](https://3dmusclelab.com/sternoclavicular-and-acromioclavicular-joint/). Ribs eight, nine, and ten connect via cartilage with the seventh costal cartilage at what is called a costochondral joint. And of course, ribs eleven and twelve don’t attach onto anything on the front of our body, hence the term “floating ribs.” ### Muscles that connect to the ribcage Because the ribcage is so centrally located and is part of relating the pelvis below to the head above, many, many muscles attach to some point on the ribcage. However, some are more strongly related to the movement of the ribcage than others. The muscles that are part of moving the ribcage in [breathing](https://3dmusclelab.com/muscular-actions-breathing/) include: - Diaphragm - Internal and external intercostals - Levatores costarum - Subcostales - Innermost intercostals - [Scalenes](https://3dmusclelab.com/neck-muscles-superficial/) - Transversus thoracis - Serratus posterior superior - Serratus posterior inferior Some of these are tiny deep muscles that make only a small contribution to the movement of the ribcage during breathing, so you may not have heard of them. Other muscles that have a connection to the ribcage include: - Subclavius - Serratus anterior - Deep spinal muscles - [Erector spinae](https://3dmusclelab.com/erector-spinae-muscles/) - Quadratus lumborum - [External and internal obliques](https://3dmusclelab.com/abdominal-muscles/) - Pectoralis minor - Pectoralis major - [Rectus abdominis](https://3dmusclelab.com/abdominal-muscles/) - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Functions of the ribcage The ribs can also be grouped based on the other structures in the body that they’re connected to and most affected by. Tom Myers of [Anatomy Trains](https://www.anatomytrains.com/) groups the ribs into two neck ribs, three chest ribs, four abdominal ribs, and three pelvic ribs. Grouping the ribs in this way can give us a different perspective on the protective function of each section and how each section is affected by the movement of other connected structures and/or organs. The scalene muscles attach to the first and second ribs, the neck ribs, so those ribs are affected by neck movement. The chest ribs, ribs three, four, and five, house our heart and lungs. Those ribs are in a relationship to those organs. The abdominal ribs, ribs six, seven, eight, and nine, shelter several organs, including our liver, pancreas, and stomach. This is also where our diaphragm is found. Finally, our pelvic ribs, ribs ten, eleven, and twelve, help protect our kidneys and adrenal glands. ### Movement The ribs articulate with the spine to allow a certain amount of movement. If those joints didn’t allow any movement at all, we would be more fragile and prone to injury and issues. Instead, we have a certain amount of movement at those joints that allows for more resiliency. We can do a certain amount of [flexion/extension, side bending, and rotation](https://3dmusclelab.com/anatomical-terms-for-movements/) (twisting) with our spine, and our ribs follow along with these movements until either the ribs themselves or the vertebrae bump into each other. ### Protection and red blood cell production Protection is one key function of our ribcage. It helps protect our heart, lungs, liver, pancreas, stomach, and kidneys, as well as the network of connective tissue and neurovascular connections between them. But, while the protective function of the ribcage might be familiar to you, our ribcage also has other roles to play. As adults, the flat bones of our ribcage are a significant location for the production of red blood cells. ### Breathing Probably the most significant function that our ribcage has its association with breathing. The movements of our ribcage are essential for making space for our breath and for creating the change in pressure that draws air in and pushes it out. The ribs do somewhat more specialized movements when we breathe. There are two main motions that happen at our rib cage that allow it to expand in three dimensions, up and out in the front and back, and out laterally from the sides. Those motions have names that describe the movements. More space is created in our ribcage in the [mediolateral direction](https://3dmusclelab.com/anatomical-terms-location-position/) when we experience what is called bucket-handle motion of the ribs during breathing. You could imagine that it looks something like the motion of a bucket handle going from a resting position against the bucket to a lifted position. That motion happens primarily at ribs seven through ten. The upper ribs also do what is referred to as a pump-handle motion. This movement is our ribcage expanding up and out from the front and back, like the motion of a pump handle from resting to lifted. In addition to the function of breathing itself, movement of the ribs during breathing results in small movements of the spine, which help hydrate our vertebral discs. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Myers, T. 2014. The Three-Ring Circus: The Upper Two Rings, Part 2. In: Anatomist’s Corner: Issues in Structural Anatomy. Self-published. Pgs. 186-195.](https://www.anatomytrains.com/product/the-anatomists-corner/) Chaitow, L. and J. DeLany. 2008. Chapter 14: The Thorax. In Clinical Application of Neuromuscular Techniques. Volume 1 – The Upper Body (Second Edition). New York, NY: Churchill Livingstone Publishing. Gormon, D. 1981. The Thoracic Vertebral Column and Muscles of the Thorax. In The Body Moveable, Volume 1 – The Trunk and Head. Pgs. 114-133. [Tang A. and B. Bordoni. 2023. Anatomy, Thorax, Muscles. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538321/](https://www.ncbi.nlm.nih.gov/books/NBK538321/) --- Source: https://3dmusclelab.com/anatomical-terms-for-movements/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Anatomical Terms For Movements ![Anatomical Terms for Movement](https://3dmusclelab.com/wp-content/uploads/2024/11/anatomical-terms-1.jpg) An essential part of [learning](https://3dmusclelab.com/whats-your-learning-style/) and [studying kinesiology](https://3dmusclelab.com/5-tips-for-learning-kinesiology/) is being able to communicate about it. Similarly to what I discussed in my last article about the [anatomical terms we use for location](https://3dmusclelab.com/anatomical-terms-location-position/) in the body, we also have anatomical terminology for movement. In this article, we’ll explore the language we use to clearly describe different types of movements in the body. ## Basic movements In the world of anatomy and [kinesiology](https://3dmusclelab.com/what-is-kinesiology/), we have terms for basic movements that occur at multiple joints. We also have specialized terms for very specific movements that occur only at individual unique joints. Let’s start our tour of anatomical terms for movement with the basic movements that take us out of and return us to [anatomical position](https://3dmusclelab.com/anatomical-position/). You’re probably familiar with many of these already. ### Flexion and extension We use the terms flexion and extension to describe movement at several joints like the [knee](https://3dmusclelab.com/knee-joint/), hip, [elbow](https://3dmusclelab.com/elbow-and-forearm-in-movement/), [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/), and others. Most generally, the term flexion means a movement that reduces the angle of a joint. For example, if I flex my [elbow joint](https://3dmusclelab.com/elbow-joint-and-forearm/), I bring my forearm closer to my upper arm. That action decreases the angle of the [elbow joint](https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/). The term extension refers to the opposite. Extension describes a movement that increases the angle of a joint. If I extend my [knee joint](https://3dmusclelab.com/knee-hyperextension/), my lower leg moves farther away from my thigh. That action increases the angle of the knee joint. Flexion and extension are movements that happen in the [sagittal plane](https://3dmusclelab.com/planes-of-movement/). ### Other types of flexion We also have some variations on the term flexion that describe specialized movements that only occur at specific [joints](https://3dmusclelab.com/synovial-joint/). Lateral flexion is the anatomical term that we use to describe side bending. That movement happens in the frontal or coronal plane. It is used to describe side bending of our [spine](https://3dmusclelab.com/exploring-the-spine/) in the torso or the lateral bending of our head on our neck. Dorsiflexion and plantarflexion describe movements of the foot that happen at the ankle joint. If you plantar flex your ankle, you take your toes farther away from the front of your foreleg. Colloquially, we refer to this as “pointing our toes.” If you dorsiflex your ankle, you bring your toes closer to the front of your foreleg. The term dorsiflexion is also used along with the term palmarflexion to describe movements of the hand at the wrist. When we use the term dorsiflexion to describe wrist movement, we are referring to the movement at the wrist that brings the back of our hand closer to our forearm. Palmarflexion, as it’s name suggests, is the term for wrist movement that brings the palm side of our hand closer to our forearm. We can also use the more general terms flexion and extension to describe the movement of the hand at the wrist in the sagittal plane. But, you will sometimes see these more specific terms used, so it’s helpful to understand what they refer to. ### Adduction and abduction Adduction and abduction describe movements that happen at many joints in the frontal or coronal plane. Adduction is a movement that brings a structure closer to the midline of our body. Abduction is the opposite. If we abduct a structure, we move it farther from the midline of our body. If you lie on your back to make a snow angel in the winter, you are abducting your arms and legs when you take them away from you. You are adducting your arms and legs when you bring them back into your body. We are most familiar with adduction and abduction movements that happen at our [shoulder](https://3dmusclelab.com/shoulder-girdle/) and [hip joints](https://3dmusclelab.com/exploring-the-hip-joint/), but there are other joints in the body where these movements happen such as some of the small joints we use to move our fingers toward and away from each other. ### Other types of adduction Horizontal adduction is also sometimes referred to as horizontal flexion. It is a movement in the transverse or horizontal plane. It’s usually used to describe the action at the shoulder joint when our arm is already in a flexed position and we bring it closer to the midline horizontally. ### Rotation Rotation is the anatomical term for turning a structure around an axis in the transverse or horizontal plane. You are probably most familiar with the rotation that we do at the two ball and socket joints in our body, the hip and the shoulder joints. In addition to movement at our ball and socket joints, we can also use the anatomical term rotation to describe turning our head on our neck or twisting our spine. We can use more specific terms to describe the direction of rotation. Medial rotation, also called internal rotation, is the anatomical term used to describe rotating our leg or our arm toward the midline of our body. Lateral rotation describes the opposite movement. Lateral rotation, also referred to as external rotation, describes a rotational movement away from the midline of our body. ### Special types of rotation In addition to the general anatomical term rotation, we have some specific terms for particular types of rotation. Circumduction is a special type of rotation that combines flexion/extension with abduction and adduction movements to move a limb in a circle at a ball and socket joint. If we move our arm in a circle through what we might think of as its full range of motion, that is circumduction. Pronation and supination are anatomical terms specifically used to describe the rotation of the forearm at the radioulnar joints. When we rotate our forearm in the direction that brings our palm up, that is supination. When we rotate our forearm in the opposite direction which brings our palm down, that is pronation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Anatomical terms for specialized movements Throughout our body, we have examples of uniquely constructed joints that require specialized movements. Many of those movements have a name. While there are too many examples to include every one of these specialized movement terms here, I have included a few of the more common ones that you are more likely to encounter. ### Elevation and depression The anatomical terms for movement, elevation and depression, are used to describe movements of the [scapula](https://3dmusclelab.com/scapula/) as well as [the jaw](https://3dmusclelab.com/jaw-muscles/). When we draw our scapulae or our mandible down, that is called depression. The opposite, when we lift a scapula or our jaw, is called elevation. ### Inversion and eversion Inversion and eversion are anatomical terms for movement that happens at the [ankle joint](https://3dmusclelab.com/exploring-the-ankle-joint/), specifically the subtalar joint. Inversion and eversion are side-to-side movements that happen in the frontal plane. In eversion, we are bringing the top of our foot closer to the midline of the body. When we do inversion, we are bringing the top of the foot farther away from the body. ### Radial and ulnar deviation Deviation is a specialized movement that happens only at the [wrist joint](https://3dmusclelab.com/hand-and-wrist-anatomy/). This side-to-side movement at our wrist is a variation on abduction and adduction. Deviation happens when the carpal bones move relative to the radius (one of the two forearm bones). Sideways movement at the wrist toward the thumb side is called radial deviation. Sideways movement at the wrist toward the pinky side is called ulnar deviation. ### Protraction and retraction Like elevation and depression, protraction and retraction are anatomical terms used to describe the movement of the scapulae and the mandible. The term retraction describes the movement of bringing either a scapula or the jaw more posterior, closer to the back of our body. With respect to the scapulae, retraction would bring them closer to the spine. Protraction is the term for drawing either the scapulae or the mandible forward. ## Conclusion Our bodies are complex, with an array of unique movements that allow us to do everything from shrug our [shoulders](https://www.yoganatomy.com/shoulder-pain-injury-in-yoga/) to drive a car. Describing and communicating this complexity of movement requires a shared language. Anatomical terms for movement help us clearly communicate what and how we’re observing movement in the body. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscle-origin-insertion-and-action/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Do The Terms Muscle Origin, Insertion, And Action Mean? ![Muscle Origin, Insertion, Action](https://3dmusclelab.com/wp-content/uploads/2019/02/origin-insertion-action.jpg) It’s important to have a language with which we can describe human anatomy and kinesiology in a meaningful way. It’s also important as we continue to study kinesiology that we understand some of the limitations of that language. Let’s take a look specifically at the idea of muscle origin, insertion, and action. ## Let’s define muscle origin, insertion, and action Muscle origins and insertions describe the places where a muscle attaches on bones. Conventionally, a muscle origin describes the attachment of a muscle on the more stable bone. The insertion then, is the attachment of a muscle on the more moveable bone. The action of the muscle describes what happens when the more mobile bone is brought toward the more stable bone during a muscular contraction. But which is the more stable bone and which is the more moveable bone? The truth is, there are many examples where there is not one single answer to that question. Conventionally, the more stable bone and the more mobile bone are identified with the understanding that the body is in [anatomical position](https://3dmusclelab.com/anatomical-position/). It’s important that we all start with an understanding of muscle origin and insertion from the same place, so we can all communicate with the same understanding of basic muscle movements. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What happens to origin, insertion, and action outside of anatomical position? In everyday life, it’s actually pretty rare for us to be in anatomical position. So, how does this change how we understand muscle origin, insertion, and action? Let’s use the example of the [psoas major muscle](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) to take a look at this. From anatomical position, the origin of the psoas major muscle is considered to be the body of vertebrae T12 through L5 and the insertion is on the lesser trochanter of the femur. Psoas major acts to flex the hip joint, which is usually shown as bringing the thigh toward the torso. But what if we’re laying on the ground? If we’re laying on the floor with our legs straight out in front of us and we lift a leg to bring our femur toward our torso, we are moving what is typically considered the insertion toward the origin. Something similar happens if we are standing, as in the one leg balancing yoga pose, and we lift one leg toward our torso. But, if we are lying down and then sit up, we are bringing our spine toward our femur. Aren’t we still flexing the hip joint? But in that case, we’re bringing the torso toward the femur. So, now which attachments are the origin and which are the insertion? Similarly, would it be the femur bones resting on the floor or the bones of the spine moving through space that are the more stable bones now? ### What happens in rotation? Things can get even more complicated when we are looking at muscles that do rotation. Let’s look at another example using the piriformis muscle. Remember when we looked at the actions of the piriformis muscle that those actions were dependent on the position of the body. Piriformis acted from anatomical position to laterally/externally rotate the hip, but when we flexed the hip and changed the position of the bones in relationship to one another, the action of piriformis changed too. When the hip joint was flexed more than 90° piriformis acted to internally rotate the hip, the opposite action that the piriformis did when we were in anatomical position. ## Conclusion The terms origin, insertion, and action are important to the language of kinesiology. However, it’s also important to understand that these are conventions that are usually described from anatomical position. They can help us communicate with one another about body movement. Muscle origin and insertion are useful landmarks to help us understand where one thing is in relationship to something else, but they’re not necessarily fixed. A more open-minded way to think about this is that muscles have at least two attachments. Whichever one is more mobile will move toward the other when the muscle that connects them contracts. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/exploring-the-adductor-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Thigh # Exploring The Adductor Muscles The adductors are a group of five muscles that are important for stabilizing and balancing our pelvis when we're standing, walking, and running. As a group, the adductors weave together to form a fan of muscles on the medial part of the thigh between the quadriceps on the front and the hamstrings on the back. ![Adductor Muscles](https://3dmusclelab.com/wp-content/uploads/2022/12/adductor-anatomy.jpg) The adductors are a group of five muscles that are important for stabilizing and balancing our pelvis when we’re standing, walking, and running. We previously covered the largest muscle in this group: [adductor magnus](https://3dmusclelab.com/adductor-magnus-muscle/). In this article, we’ll take a look at the four other adductor muscles. ## Quick facts Origin · Insertion · Action - **Origin**: **Pectineus:** superior pubic ramus **Adductor brevis:** inferior pubic ramus **Adductor longus:** pubic ramus, just laterally to the pubic symphysis **Gracilis:** inferior pubic ramus - **Insertion**: **Pectineus:** pectineal line, a bony ridge along the femur from the lesser trochanter to the linea aspera **Adductor brevis:** upper third of the linea aspera **Adductor longus:** middle third of the linea aspera of the femur **Gracilis:** pes anserine of the tibia - **Action**: **Pectineus:** adduction of the thigh at the hip, flexion of the thigh at the hip **Adductor brevis:** adduction of the thigh at the hip, flexion of the thigh at the hip, medial rotation of the thigh at the hip (depending on position) **Adductor longus:** adduction of the thigh at the hip, flexion of the thigh at the hip, medial rotation of the thigh at the hip (depending on position) **Gracilis:** adduction of the thigh at the hip, flexing the knee when the knee is straight, medial rotation of the lower leg at the knee joint ## What are the adductor muscles? This is a large group of muscles in our thigh. If we include adductor magnus, this group covers about a quarter of the volume of space taken up by muscles in our thigh (Watanabe et al., 2009). The five muscles of the adductor group are: pectineus, adductor brevis, adductor longus, gracilis, and as I mentioned above, adductor magnus. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Where are the adductor muscles? ### Muscle attachments As a group, the adductors weave together to form a fan of muscles on the medial part of the thigh between the quadriceps on the front and the hamstrings on the back. They attach at their superior end to various places along the medial, and posterior aspects of the [pubic bone](https://3dmusclelab.com/exploring-the-pelvis/). With the exception of gracilis, each of these muscles attaches at their inferior end to a different point along a bony ridge on the back of the femur called the linea aspera. As you’ll see below, gracilis is the longest in this muscle group. It goes all the way to the tibia before it attaches at its inferior end. Let’s look at each of these [muscle’s attachments](https://3dmusclelab.com/muscle-origin-insertion-and-action/) more specifically. Pectineus attaches superiorly to the superior pubic ramus and inferiorly to the pectineal line. The pectineal line is a bony ridge that extends along the femur from the lesser trochanter to the linea aspera. Adductor brevis attaches superiorly to the inferior pubic ramus and inferiorly to the upper third of the linea aspera. Adductor longus attaches superiorly to the pubic ramus, just laterally to the pubic symphysis. Inferiorly, it attaches to the middle third of the linea aspera of the femur. Finally, gracilis attaches superiorly to the inferior pubic ramus. It’s unique among the adductors in that it is the only one of the group to cross two joints: the hip joint and the knee joint. This is because its inferior attachment is at the pes anserine of the tibia. ## Muscle actions As a group, all of the adductor muscles contribute to adduction of the thigh at the hip. Additionally, adductor longus, adductor brevis, and pectineus also assist with flexion of the thigh at the hip. Adductor longus and Adductor brevis can assist with medial rotation of the thigh at the hip as well, depending on the position that we’re in. Finally, gracilis, as I said, is the only one of this muscle group to cross the knee joint and the hip joint. So, it can also assist with flexing the knee when the knee is straight and with medial rotation of the [lower leg](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) at the [knee joint](https://3dmusclelab.com/knee-hyperextension/). It may not be obvious when we do adduction of the thigh at the hip in everyday movements. It’s important to remember that muscles don’t just [function to create movement](https://3dmusclelab.com/muscle-contractions/), they also function to control movement. Walking is an example where adduction is a necessary part of a chain of actions to control our movement. While we might not think of adduction right away as part of how we walk, it is part of the connected series of actions in walking. During walking, the adductors’ main action is to work in relation to their antagonists (the abductors) to help stabilize each side of the pelvis as we take a step. The adductors also work in relation to the abductors of each hip to help stabilize our pelvis when we are in a simple standing position. ## Conclusion Although they sometimes get overlooked when we give our attention to our more dynamic thigh muscles like the quadriceps or [hamstrings](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/), the adductor muscles are an important group to know. They have a key role in assisting those more dynamic muscles in their actions. They are also critical to maintaining a balanced posture in our lower body in stillness and in movement. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. Delany. 2011. Chapter 11: The Pelvis. In: Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body. (Second Edition). Churchill Livingstone Elsevier. New York, NY. Travell, J.G and D.G. Simons, 1993. Chapter 13: Pectineus Muscle and Chapter 15: Adductor Muscles of the Hip. In: Myofascial Pain and Dysfunction- The Trigger Point Manual. Vol. 2 – The Lower Extremities. Lippincott, Williams, and Wilkins Philadelphia, PA. [Watanabe, K., K. Katayama, K. Ishida, and H. Akima. 2009. Electromyographic analysis of hip adductor muscles during incremental fatiguing pedaling exercise. European Journal of Applied Physiology. 106:815-825.](https://pubmed.ncbi.nlm.nih.gov/19466446/) --- Source: https://3dmusclelab.com/exploring-the-ankle-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Exploring The Ankle Joint ![Exploring The Ankle Joint](https://3dmusclelab.com/wp-content/uploads/2023/07/ankle-joint-t.jpg) The ankle joint is a critical piece of our body for supporting [functional movement](https://3dmusclelab.com/functional-movement/). It’s part of what allows us to respond to walking or running on different types and uneven surfaces. It’s also a necessary component of other types of movement like jumping and kicking. And it also helps us maintain our balance and shift our weight as we’re doing all of those kinds of movements. So, as you might imagine, the ankle is complicated. In fact, if we include all the structures of the foot and ankle together, we have 28 bones, 34 muscles, and 112 ligaments that come together to create the whole [tensegrity](https://en.wikipedia.org/wiki/Tensegrity) of our foot and ankle. Let’s take a look at the structures that make up the ankle joint specifically, and the actions that happen there. ## What structures make up the ankle? It’s important to understand that what we refer to as the ankle joint, is actually two [joints](https://3dmusclelab.com/synovial-joint/). These two main joints work together to create the wide range of movements that we need at our ankles. The combination of movements from these two joints allows us to adapt to all kinds of different terrain under our feet. Additionally, we have a series of [muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) and ligaments that surround and connect each of these two joints, and connect the bones within these joints to other bones in the foot. These [muscles](https://3dmusclelab.com/muscle-contractions/) and ligaments are critical for maintaining the balance between mobility and stability that we need. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Bones in the ankle The tibia, fibula, talus, and calcaneus are all important bones to know when thinking about the ankle joint. What we often think of as the ankle is really more than one joint. So it’s important to know where these bones are and how they relate to one another to understand function and [dysfunction at the ankle](https://3dmusclelab.com/exploring-plantar-fasciitis/). The tibia is the larger of our lower leg bones. The fibula is the smaller of our lower leg bones. The talus is a wedge-shaped bone that is wider in the front than in the back. It sits just underneath the tibia and fibula and on top of the calcaneus. The calcaneus is our heel bone. It sits underneath (distal) and extends behind (posterior) the talus. ## Joints at the ankle The two main joints that make up what we think of as the ankle are the tibiotalar joint (also called the talocrural joint) and the subtalar joint. In practice, there are also additional articulations of bones of the foot that contribute to the full range of motion in our ankles and feet that I won’t go into in this article. Our ankles are complicated! ### Tibiotalar joint The tibiotalar joint is located where the tibia and the fibula meet the talus. The rounded bony prominence on the lateral side of our ankle (called the lateral malleolus) is the bottom of the fibula where it meets the talus. The rounded bony prominence on the medial side of our ankle (called the medial malleolus) is the bottom of the tibia where it meets the talus. The shape of the bones helps create a snug fit between the tibia, fibula, and talus. The way the malleoli of the ankle hug the tarsal bone creates a sort of biomechanical version of a mortise, like the way a perfectly shaped tab on a piece of wood inserts snugly into a hole to join to sections on a piece of furniture. You can imagine how that would add some stability to what can be a very mobile part of our body. The tibiotalar joint is a hinge joint. It is responsible for the hinging movements at our ankle joint. It does dorsiflexion and plantarflexion of the foot at the ankle. ### Subtalar joint We have a second joint that is necessary for the full range of movements we use at the ankle. The subtalar joint is located where the talus meets the calcaneus. It’s a gliding joint. It’s this joint that allows us to tilt our foot medially and laterally in eversion and inversion at the ankle. ## Movements at the ankle The main movements that we do at our ankle joints are: - Plantarflexion - Dorsiflexion - Eversion - Inversion Plantarflexion and dorsiflexion happen at the tibiotalar joint. Plantarflexion happens when we point our foot (like stepping on a gas pedal). Dorsiflexion happens when we flex our ankle to bring the foot up toward our body (like when we heel strike while walking). Eversion and inversion happen at the subtalar joint. Eversion happens when our foot rolls in to bring the big-toe side of our foot closer to the ground. Inversion happens when we roll our foot out to bring the pinky-toe side of our foot closer to the ground. You might have also heard the terms supination and pronation used in relation to the ankle. Supination and pronation are actually combinations of plantarflexion/dorsiflexion and eversion/inversion that happen during movement. It’s normal for our ankles to move in and out of moments of supination and pronation as we walk. However, if we have an excess of either supination or pronation and our ankle doesn’t return to neutral in a static standing position, then that can indicate an imbalance in the [connective tissues](https://3dmusclelab.com/what-is-connective-tissue/), an injury, or some other kind of issue with the ankle. ![Structures Of The Ankle Joint](https://3dmusclelab.com/wp-content/uploads/2023/07/ankle-joint-labels.jpg) ## Muscles at the ankle joint The ankle joint is one key place in our lower body kinetic chain that makes it possible for us to respond to all the changes that can happen in the ground beneath us. In order to provide that adaptability, there are a lot of structures that help hold the ankle joint together while allowing it to move in many different directions. Let’s take a look at the [muscles](https://3dmusclelab.com/what-is-a-muscle/) that cross the ankle joint. [Muscles](https://3dmusclelab.com/muscle-origin-insertion-and-action/) that move (or assist) the ankle into plantarflexion: - Gastrocnemius - Soleus - Plantaris - Tibialis posterior - Flexor digitorum longus - Flexor hallucis longus - [Fibularis longus](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) - Fibularis brevis Muscles that move (or assist) the ankle into dorsiflexion: - [Tibialis anterior](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) - Extensor digitorum longus - Extensor hallucis longus - Fibularis tertius Muscles that move (or assist) the ankle into eversion: - [Fibularis longus](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) - Fibularis brevis - Fibularis tertius Muscles that move (or assist) the ankle into inversion: - [Tibialis anterior](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) - Tibialis posterior ## Ligaments As much as we need many directions of mobility and adaptability at the ankle joint, we also need stability. Most of our body weight is passing through our ankles as we stand and walk. When we add momentum into the equation, by running or jumping for example, then we need even more stability at our ankle joints. One of the sources of that stability is a series of [ligaments](https://3dmusclelab.com/ligaments-and-tendons/) that fan out in many different directions to help hold things together at the ankle. Our ligaments work with our muscles and other soft tissue to help distribute load in a balanced way as we move. This makes our foot and ankle a great example of [tensegrity](https://en.wikipedia.org/wiki/Tensegrity)! ### Major ligaments of the tibiotalar and subtalar joints (Many of these ligaments can be separated into more than one distinct band which also have names, but are beyond the scope of this article.) - Deltoid ligament—this ligament connects the tibia to the navicular, calcaneus, and the talus - Anterior talofibular ligament—this ligament connects the talus to the fibula - Posterior talofibular ligament—this ligament connects the talus to the fibula - Calcaneofibular ligament—this ligament connects the fibula to the calcaneus - Lateral, medial, and posterior branches of the talocalcaneal ligament—these connect the talus to the calcaneus - Interosseous talocalcaneal ligament—this ligament connects the talus to the calcaneus - Anterior (or cervical) talocalcaneal ligament—this ligament connects the talus to the calcaneus ## Conclusion The ankle is a complex area of joints, muscles, and ligaments that allows us to be highly adaptable as we move over many different kinds of surfaces. We need healthy functioning ankle joints for walking, running, jumping and so many activities we do on our feet. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/elbow-joint-and-forearm/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Structures Are Found In The Elbow Joint And Forearm? ![The Elbow Joint](https://3dmusclelab.com/wp-content/uploads/2020/05/elbow-joint-structure.jpg) The elbow joints often don’t get as much attention as the more popular hip joints and shoulder joints, but we’d find it hard to do many daily tasks without them. In this article we’ll take a closer look at the elbow joint, the main muscles that cross it, and the movements that happen there. ## Bones of the elbow joint The elbow joint is a general name that is technically comprised of two joints: the humeroulnar joint and the humeroradial joint. There is a third joint that is sometimes referred to as a part of the elbow, but it is more often considered independent of the elbow joint itself because it does different movements. This is the proximal radioulnar joint. Let’s look at each of these individual joints a little closer. The humeroulnar joint is where the upper arm bone, the humerus, meets the ulna, the smaller of the two forearm bones. The second part of the elbow joint, the humeroradial joint, is where the humerus meets the radius, the larger of the two forearm bones. The third joint that we’ll discuss in relation to the elbow is the proximal radioulnar joint. This is where the proximal (closer to the head) end of the ulna and radius meet and articulate with one another, separately from the articulations with the humerus. There is also a distal (farther from the head) radioulnar joint which you’ll remember we already covered as part of the [wrist joints](https://3dmusclelab.com/hand-and-wrist-anatomy/). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Movements of the elbow joint The humeroulnar joint and humeroradial joint, which make up what we more generally know as the elbow joint, make a hinge joint that does the movements of flexion and extension of the elbow. At the proximal radioulnar joint, the articulation between the radius and ulna is a pivot joint which allows us to supinate and pronate (types of rotation) the forearm. ## Muscles of the elbow joint and forearm Let’s take a look at the muscles at the elbow joint that contribute to its actions. Flexors of the forearm: - Biceps brachii - Brachialis - Brachioradialis Extensors of the elbow: - Triceps brachii - Anconeus Pronators of the forearm at the proximal radioulnar joint: - Pronator teres - Pronator quadratus - Brachioradialis (assists pronation) Supinators of the forearm: - Supinator muscle - Biceps brachii (assists supination) The elbow joint makes so many important actions possible. It’s the link in the kinetic chain between our shoulder joint and our wrist and hand. So many movements that we take for granted each day rely on the movements of the elbow joint to make them possible, from turning a doorknob to drinking a glass of water. Hopefully you now have a better understanding of the structures that are found there. If you’d like to learn more about the surrounding joints in the kinetic chain of the arm, check out the articles [Hand And Wrist Anatomy](https://3dmusclelab.com/hand-and-wrist-anatomy/) and [What Is The Shoulder Girdle Or Shoulder Complex?](https://3dmusclelab.com/shoulder-girdle/) The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/erector-spinae-muscles/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Are The Erector Spinae Muscles? ![Erector Spinae Muscles](https://3dmusclelab.com/wp-content/uploads/2020/01/Erector-spinae-muscles.png) The erector spinae muscles are a group of muscles that belong to an even broader group of muscles called the paraspinal muscles. You can get a sense from breaking down the name where this larger group of muscles is located. ‘Para’ means alongside or beside. ‘Spinal’, of course, refers to the spine. So, the erector spinae muscles belong to a bigger group of muscles that are all located along the spine. Other muscles included in the paraspinal muscle group include the rotatores and the multifidi. The erector spinae muscles include three main muscles which themselves can also be divided into sections. The erector spinae muscles include: iliocostalis, longissimus, and spinalis. Each of these muscles can be divided into three sections. We have iliocostalis cervicis, iliocostalis thoracis, and iliocostalis lumborum. We have longissimus capitis, longissimus cervicis, and longissimus thoracis. Finally, we have spinalis capitis, spinalis cervicis, and spinalis thoracis. ## Where are the erector spinae muscles? As we described above, most generally we find the erector spinae muscles alongside the spine. The spinalis muscles are most medially located. That is, they are closest to the spine. Next to spinalis we find the longissimus muscles. The iliocostalis are located most laterally of the erector spinae muscles. Let’s break each of these muscles down into their three smaller muscles and look at their attachments. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle origins - Spinalis capitis: spinous processes of C7 to about T2 (but often hard to differentiate from semispinalis capitis) - Spinalis cervicis: nuchal ligament and spinous processes C6 or C7 - Spinalis thoracis: spinous processes T10 to L3 - Longissimus capitis: transverse processes of T1 to T5 and articular processes of C5 to C7 - Longissimus cervicis: transverse processes of T1 to T5 - Longissimus thoracis: sacrum, spinous and transverse processes of all lumbar and thoracic vertebrae - Iliocostalis cervicis: angle of ribs 3 through 6 - Iliocostalis thoracis: superior border of the lower 6 ribs - Iliocostalis lumborum: medial iliac crest, sacrum, and spinous processes of the lumbar spine ## Muscle insertions - Spinalis capitis: lateral nuchal line (but often hard to differentiate from semispinalis capitis) - Spinalis cervicis: spinous processes C2 to C4 - Spinalis thoracis: spinous processes T2 to T8 - Longissimus capitis: posterior mastoid process - Longissimus cervicis: transverse processes of C2 to C6 - Longissimus thoracis: transverse processes of all thoracic vertebrae - Iliocostalis cervicis: transverse processes C4 to C6 - Iliocostalis thoracis: superior border of the upper 6 ribs and transverse process of C7 - Iliocostalis lumborum: inferior border of the lower 6 or 7 ribs ## Muscle actions - All of the erector spinae muscles work bilaterally to extend the spine. - Longissimus thoracis and longissimus cervicis also function unilaterally to laterally flex the spine to the same side. - Longissimus capitis functions unilaterally to rotate the head to the same side. - The iliocostalis muscles and spinalis capitis work unilaterally to laterally flex the spine to the same side. While the erector spinae muscle group is very important for extending the spine, there are also many other muscles that contribute to moving the spine in different ways. If you want to learn more about other muscles that move the spine check out our post: [Exploring The Spine](https://3dmusclelab.com/exploring-the-spine/)! The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/exploring-the-hip-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Exploring The Hip Joint ![The Hip Joint](https://3dmusclelab.com/wp-content/uploads/2024/08/hip-joint.jpg) Although most people are familiar with the general location of the hip joint, the network of bones, muscles, and ligaments that support their function is actually quite complex. These two joints have to mediate between our legs’ ability to adapt to the ground below and the response of our pelvis to what’s happening with our torso above. To complicate things further, our right and left hip joints have to work together to coordinate our movement. Healthy mobile and stable joints are essential to our [functional gait](https://3dmusclelab.com/what-is-the-gait-cycle/). During each step we take, our two hip joints function independently, but still in coordination with each other. When we walk we transfer our weight to one leg, while swinging our other leg forward to take a step. These joints are involved in every part of that process. That’s a lot to ask of our hip joints! In this article, we’ll explore the structures that make up these joints and how they all work together to support movement. ## The hip joint The hip joint is where the top of our leg meets our [pelvis](https://3dmusclelab.com/exploring-the-pelvis/). We have two hip joints, of course, a right side and a left side. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What structures make up the hip joint? ### Bones On each of the right and left sides of the body, we have two bony connections that come together to create the hip joint. The top of the femur, which is the long bone of your thigh, ends in a knobby bit, called the head of the femur. That is the ball of the ball and socket joint. The femoral head fits into a depression in your pelvis, called the acetabulum. The acetabulum is the socket of the ball and socket joint. As you might guess, if you put the names of the two structures together, the technical name of the joint is the acetabulofemoral joint. ### Joint type The joint type of the hip joint is a ball and socket [synovial joint](https://3dmusclelab.com/synovial-joint/). One of the hallmarks of a ball and socket joint is the ability of the joint to move in all planes. So, the hip is considered a multiaxial joint. It can move, not only in all [three cardinal planes](https://3dmusclelab.com/planes-of-movement/), but in many directions in between them too. The multiplanar movement of the hip joint supports its function as a key joint in the lower body kinetic chain, all of which help us adapt to the changing nature of the ground under our feet. Its stability and the support of the strong musculature make this joint ideal for its function in weight-bearing and force transmission. ### Ligaments The hip joint is one of only two ball and socket-type joints in the body. The other ball and socket joint is your shoulder joint. In contrast to your shoulder joint, however, your hip joint is an incredibly stable joint. One reason for this is the depth of the hip socket that the head of your femur fits within. Another reason for the strength of this joint is the thick, dense [ligaments](https://3dmusclelab.com/ligaments-and-tendons/) that bind the pelvis to the femur. Three ligaments help maintain the stability of the joint. Those ligaments are the iliofemoral ligament, the pubofemoral ligament on the anterior side, and the ischiofemoral ligament on the posterior side. ### Labrum There is another structure that’s key to maintaining the integrity of each hip joint. Like the shoulder ball and socket joint, the hip joint is lined with an additional piece of cartilage called a [labrum](https://www.yoganatomy.com/yoga-tearing-labrums/) to help manage the balance of mobility and stability of the hip. ### Muscles that cross the hip joint Remember that [muscles can contract](https://3dmusclelab.com/muscle-contractions/) to create movement, resist movement, and work to stabilize joints. When it comes to the muscles of the hip joint (and many other muscles too), most of the [muscles can contribute to more than one action](https://3dmusclelab.com/muscle-origin-insertion-and-action/). In the next section where we list the [muscles](https://3dmusclelab.com/what-is-a-muscle/) by their action, you’ll see that they appear in more than one list. The muscles that cross the hip joint include: - Rectus femoris - [Psoas major](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) - [Iliacus](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) - Pectineus - Adductor brevis - Adductor longus - Gracilis - Adductor magnus - Biceps femoris (long head) - Semimembranosus - Semitendinosus - Sartorius - Gluteus maximus - Gluteus medius - Gluteus minimus - Tensor fascia latae - Obturator internus - Obturator externus - [Piriformis](https://3dmusclelab.com/piriformis-muscle/) - Quadratus femoris - Gemellus superior - Gemellus inferior ![Hip Joint Muscles](https://3dmusclelab.com/wp-content/uploads/2024/08/hip-joint-muscles.jpg) ## Movements at the hip joint The main movements at our hip joint are: - Flexion - Extension - Abduction - Adduction - Internal/medial rotation - External/lateral rotation - Circumduction However, it’s important to remember here that our bodies are complex and three-dimensional. Because the hip joint does tri-planar movement, as well as many movements like circumduction that are in addition to moving along the lines of the three cardinal planes, we need to think of movement at the hip joint more broadly than at other joints with a more limited scope of movements. ### Controversy at the hip joint Most main actions at the hip joint involve certain muscles whose primary job is to create that action. However, many other muscles may assist with each action. Exactly which muscles contribute to which movements depends on the starting position of the hip joint during the movement. If we change the position of the joint from [anatomical position](https://3dmusclelab.com/anatomical-position/) to flexed past 90 degrees, for example, the physics of how the muscles around the joint work on and adapt to forces on the joint also change. The variety of ways that some muscles assist particular movements at the hip joint are not fully understood by anatomists because the actions of many deeper muscles are hard to measure in a laboratory setting. There is some debate among researchers over the possible muscular contributions to movements at this joint. So, understand that although we list muscles and their associated movements below, researchers are still learning about the [kinesiology](https://3dmusclelab.com/anatomical-position/) of the hip joint. For that reason, you may see differences between references regarding which muscles assist which actions. ### Flexion Depending on the position of the hip joint, these muscles contribute to flexion: - Rectus femoris - [Iliacus](https://3dmusclelab.com/iliopsoas-and-movement/) - [Psoas major](https://3dmusclelab.com/iliopsoas-and-movement/) - Tensor fascia latae - Pectineus - Adductor brevis - Adductor longus Sartorius, gracilis, and the anterior fibers of gluteus minimus and medius may assist with hip flexion in some situations. ### Extension These muscles can contribute to extension: - Gluteus maximus - Adductor magnus - [Biceps femoris (long head)](https://3dmusclelab.com/anatomy-of-the-hamstrings/) - [Semimembranosus](https://3dmusclelab.com/anatomy-of-the-hamstrings/) - [Semitendinosus](https://3dmusclelab.com/anatomy-of-the-hamstrings/) The posterior fibers of the gluteus minimus and medius as well as the deep six lateral rotators acting bilaterally can potentially assist with hip extension in some circumstances. ### Abduction These muscles can contribute to [abduction at the hip joint](https://3dmusclelab.com/lateral-hip-muscles-in-movement/): - [Gluteus medius](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/) - [Gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/) - [Tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/) Under certain circumstances, piriformis and sartorius may assist with abduction of the hip. ### Adduction These muscles can contribute to [adduction at the hip joint](https://3dmusclelab.com/exploring-the-adductor-muscles/): - Pectineus - Adductor brevis - Adductor longus - Gracilis - [Adductor magnus](https://3dmusclelab.com/adductor-magnus-muscle/) In some situations gluteus maximus, quadratus femoris, obturator internus, and biceps femoris can also contribute to adduction. ### Lateral rotation These [muscles can contribute to external (lateral) rotation](https://3dmusclelab.com/deep-six-lateral-rotators-movement/): - [Obturator internus](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - [Obturator externus](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - [Piriformis](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - [Quadratus femoris](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - [Gemellus superior](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - [Gemellus inferior](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) - Gluteus maximus - Posterior fibers of gluteus medius and minimus In particular situations, the sartorius can also assist with lateral rotation. ### Medial rotation These muscles can contribute to internal (medial) rotation: - Tensor fascia latae - Anterior fibers of gluteus medius and minimus Medial, or internal rotation at the hip joint, is an interesting action because we don’t have a muscle or muscles whose primary action is internal rotation. Instead, we have smaller muscles that work together to create internal rotation. Depending on the position of the hip joint, it’s possible for adductor longus, adductor brevis, pectineus, and piriformis to assist with the action of internal rotation. ## Conclusion The hip joints might be among the joints in the body that people are most familiar with. However, their complexity is often far beyond what most people imagine. They are a crucial part of transferring force from the ground into the torso and from the upper body into the legs. The hip joints work with other key structures to make it possible for us to stand, walk, run, and do just about any other [functional movement](https://3dmusclelab.com/functional-movement/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 12: The Hip. In Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body (Second Edition). New York, NY: Churchill Livingstone Publishing. [Neumann, D.A. 2010. Kinesiology of the hip: A focus on muscular actions. Journal of Orthopaedic and Sports Physical Therapy. 40(2):82-94.](https://pubmed.ncbi.nlm.nih.gov/20118525/) --- Source: https://3dmusclelab.com/knee-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Structures Make Up The Knee? ![The Knee Joint](https://3dmusclelab.com/wp-content/uploads/2020/10/knee-joint.jpg) The knee is a complex and critical joint. When it works in cooperation with the hip and ankle joints, it makes it possible for us to walk and run. The knee can often be a site of injuries and dysfunction because of the nature of the demands from the body that it has to meet. The knee has to be stable enough to take our weight, even when we land with momentum, as in running and jumping. It also has to be mobile enough to allow us to place our feet and pivot as we do in tennis and basketball. Many sports ask a lot from this critical joint. Let’s take a closer look at the knee joint. ## Bones in the knee There are three bones that could be considered part of the knee joint: - Femur – This is the long bone of the thigh. - Tibia – This is the larger of the two lower leg bones. - Patella – This is the sesamoid-shaped bone that we usually know as the “knee cap”. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Joints at the knee The joint that we generally think of as the knee joint is the place where the femur, the long bone of the thigh, meets the tibia, the larger of the two lower leg bones. This joint is called either the femorotibial joint or the tibiofemoral joint. It’s a hinge joint, so it primarily does uni-axial movement, but keep reading to learn about the exceptions to this. We also have a second joint which could be considered part of the knee joint. This is where the patella, our knee cap bone, meets the femur. That joint is called the patellofemoral joint and it is a gliding joint. Two flat areas of the patella glide along the condyles of the femur to create this joint. ## Muscles, ligaments, and other structures at the knee There are a number of muscles, ligaments, and other structures that are important for supporting the knee joint in its function. Let’s start by taking a look at the muscles that cross the knee joint. #### Knee extenders: - Rectus femoris - Vastus lateralis - Vastus medialis - Vastus intermedius #### Knee flexors: - Semimembranosus - Semitendinosus - Biceps femoris - Gastrocnemius - Gracilis - Sartorius - Popliteus Besides the muscles that cross the knee joint, we also have a number of other structures that help create the right balance between stability and mobility at the knee joint. There are four strong ligaments, one on each side of the knee joint, and two between the two bones, that help maintain stability of the knee joint. Each of these ligaments allows or restricts movement at the knee joint in different ways: - Anterior Cruciate Ligament - Posterior Cruciate Ligament - Medial Collateral Ligament - Lateral Collateral Ligament On the lateral side of the knee joint we have another important structure that contributes to knee stability: the [iliotibial band](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/) (IT band). The IT band is a long section of ligamentous fascia that connects the hip to the knee. Among other functions, it helps prevent too much lateral or anterior movement at the knee joint when we’re walking or running. We also have a strong ligament that helps hold the patella in place where it connects to the femur. The patellar ligament is formed when the four quadriceps muscles (rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis) merge to form a common tendon just before they attach to the tibia. The knee joint uses a very specialized structure called a meniscus to help absorb force and distribute pressure coming through the joint, while still allowing the knee to move. Each knee joint has two of these semi-circular pieces of cartilage (menisci): a medial meniscus on the inside of the knee and a lateral meniscus on the outside of the knee. ## Movements at the knee Because the femorotibial joint functions primarily as a hinge joint, its main movements are flexion and extension of the lower leg. However, when it is flexed between 30 and 90 degrees, the knee can rotate, both medially and laterally, a small amount. When the knee is flexed between 30 and 90 degrees, it can rotate medially up to about 10 degrees and laterally up to about 45 degrees. When the movements of the hip, knee, and ankle are combined, it allows us to pick up our legs and feet and place them, so we can walk and run. ## Conclusion The knee joint is an especially important joint for our most basic functional movement, walking. While the demands that we place on the knee can make it vulnerable to injury and dysfunction, its unique shape and actions also allow us to move in a wide range of ways. The knee joint works with other joints in the body to make it possible for us to participate in activities from gymnastics to soccer to high jumping. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/exploring-the-pelvis/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Structures Make Up The Pelvis? ![Exploring the Pelvis](https://3dmusclelab.com/wp-content/uploads/2019/07/exploring-pelvis.jpg) The pelvic structure is the center of our body. Our center of gravity is found there. The movement (or lack of movement) at the pelvis directly influences the movement available to the legs below and the spine above. Its primary function is to support the spine above and facilitate movement of the legs below. ## Bones The overall shape of the pelvic structure varies in the population as a whole. It also varies between men and women because women’s pelvises are shaped to accommodate childbirth. There are two sides, or halves, to the pelvis. These two sides connect at the sacrum on the posterior side and at the pubic symphysis on the anterior side. Each half is composed of three bones: Ilium —— The ilium is the elephant ear-shaped, or fan-shaped, bone on the lateral side of each side of the pelvis. The crest or upper ridge of the ilium runs from the anterior superior iliac spine (ASIS – an important bony landmark for muscle attachment) on the front, to the posterior superior iliac spine (PSIS) on the back. Ischium —— The ischium is the posterior and inferior bony aspect. Pubic bone —— The pubic bone is the anterior, inferior bony part of the pelvis. The pubic bone is also an important bony landmark for muscle attachment. These three bones are truly separate bones at birth, when they are separated by cartilage, but they become fused by the time we reach adulthood. Additionally, there are two more bones which connect the two sides: Sacrum —— The sacrum is a triangular-shaped bone that is actually considered to be composed of five fused vertebrae. It fits like a wedge between the two ilia. Coccyx —— The coccyx is more commonly referred to as our “tail bone”. It’s made up of three, four, or sometimes five fused vertebrae. The sacrum and coccyx bones fit between each half of the pelvis on the posterior side. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Joints There are several important joints at the pelvis. They function to connect the two halves together and also to connect it to the rest of the body. Sacroiliac joints (SI joints) —— This is where the sacrum articulates with the ilium bone on each side of the pelvis. The SI joints connect the two halves on the posterior side of the body. The SI joints are also the points where the pelvis technically connects to the upper body because the sacrum is connected to the spine on its superior end. Pubic symphysis —— This is where the two halves articulate with one another on the anterior side of the body. Acetabulofemoral joints —— These two joints are better known as the hip joints. This is technically where the pelvis connects to the lower body. ## Muscles and ligaments Strong ligaments are an important part of what connects the two halves of the pelvic structure. They include: - Iliolumbar ligaments - Sacroiliac ligaments - Sacrotuberous ligaments - Sacrococcygeal ligaments - Sacrospinous ligaments As the pelvis is central to movement in both the legs below and the spine above, a long list of muscles connect to it both above and below. They include: - Gluteus maximus, gluteus medius, gluteus minimus, and tensor fascia latae - All five adductors - All three hamstrings - Rectus femoris - Sartorius - All six lateral rotators of the hip - A group of pelvic floor muscles - Iliopsoas - Quadratus lumborum - Rectus abdominis - External and internal obliques - Transverse abdominis - Latissimus dorsi - Erector spinae group ## Movements at the pelvis Since there are two halves of the pelvis, each of them can move independently of one another. This is important, as this independent movement is necessary for walking, running, and many other movements. - The pelvis can tilt anteriorly or posteriorly. That movement happens at the acetabulofemoral joints. - Each side of the pelvis can also do elevation and depression. Elevation is more commonly referred to as “hip hiking”. - Each side of the pelvis can rotate. - At the SI joints, the sacrum can move in relationship to the rest of the pelvis. This forward or back tipping movement is called nutation and counternutation. The pelvis is an important part of our body structure and necessary for our most basic movement. If you’d like to learn more about the muscles that attach to it, check out our posts on the [piriformis muscle](https://3dmusclelab.com/piriformis-muscle/) and the [iliopsoas](https://3dmusclelab.com/contact-your-iliopsoas-muscle/). If you want to dive deeper into this complex structure, these articles from the National Library of Medicine are a great resource: [https://www.ncbi.nlm.nih.gov/books/NBK482258/](https://www.ncbi.nlm.nih.gov/books/NBK482258/) and [https://www.ncbi.nlm.nih.gov/books/NBK551580/](https://www.ncbi.nlm.nih.gov/books/NBK551580/) The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/sacroiliac-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Exploring The Sacroiliac Joint ![Sacroiliac Joint](https://3dmusclelab.com/wp-content/uploads/2023/03/si-joint-back-pelvis.jpg) The sacroiliac joints, which connect our sacrum to our pelvis, are curious and particularly unique joints in our body. The sacrum forms the connection between our spine and our pelvis, physically connecting our upper and lower body. The joints where that connection happens are essential for shock absorption and load transfer between our torso and the legs. They make it possible for us to stand, walk, and run. Let’s take a look at what we know and what we don’t know about the anatomy and function of the sacroiliac (SI) joints. ## What structures make up the sacroiliac or SI joints? ### Bones of the SI joint We actually have two sacroiliac joints, one on each side of our [pelvis](https://3dmusclelab.com/exploring-the-pelvis/). The SI joints are found where the sacrum, the triangular bone at the base of our spine, meets our two ilium bones. Remember the ilium is the large, sort of elephant-ear-shaped bone of our pelvis. Where the sacrum articulates with the ilium on each side of our pelvis are our right and left SI joints. ![SI Joint Bones](https://3dmusclelab.com/wp-content/uploads/2023/03/si-joint-above-pelvis.jpg) The SI joint is tiny. It’s considered a [synovial joint](https://3dmusclelab.com/synovial-joint/), however, some sections of this joint are more fibrous than typical synovial joints (Ashby et al., 2021). The distal section is cartilaginous and functions like a synovial joint, but the proximal section is more fibrous (Ashby et al., 2021; Vleeming et al., 2012). ### Muscles and the SI joint Let’s take a look at the muscles that affect the sacroiliac joint. Interestingly, there aren’t any muscles that attach directly and have a line of pull from the sacrum to the ilium. The closest direct muscular connection we have is the [piriformis muscle](https://3dmusclelab.com/piriformis-muscle/) which attaches at one end to the anterior (front/inside) side of the sacrum and attaches at the other end to the greater trochanter of the femur. We also have the gluteus maximus which attaches at its proximal end to both the ilium and the sacrum (along with other sites) and then attaches at its distal end to the gluteal tuberosity on the femur and into the iliotibial band. Unlike other joints in the body, [muscular actions](https://3dmusclelab.com/muscle-contractions/) on the SI joints are primarily indirect. However, muscular tension and position do affect how force moves through those joints. The cascade of relationships between the muscular and ligamentous interactions is extremely complex though, making it very difficult to pinpoint sources of pain or dysfunction when they occur at the sacroiliac joints. You could imagine that any [muscle](https://3dmusclelab.com/what-is-a-muscle/) or [fascial sheet](https://3dmusclelab.com/what-is-muscle-fascia/) which attaches to the sacrum or the ilium could potentially affect tension at the SI joint. Those could include (but not be limited to): piriformis, gluteus maximus, erector spinae, multifidus, and the thoracolumbar fascia. The same could be said about muscles that attach to the ilium. Additionally, muscles that affect the pull and position of the other pelvic bones, or the spine, could indirectly affect the direction and amount of tension at the SI joints. It’s easy to see how the relationship of tension between muscles and the sacroiliac joint quickly gets complicated. ### Ligaments When it comes to the sacroiliac joints, the structures that connect the bones are just one more way that these joints are unique among joints in the body. Arguably, the most important structures that cross the SI joints are not the muscles. The primary connections around the sacrum are actually [ligaments](https://3dmusclelab.com/ligaments-and-tendons/), which makes the sacroiliac joints very different than typical synovial joints. The ligaments that cross the SI joints or extend from ligaments which do, include: - Anterior sacroiliac ligament - Long posterior sacroiliac ligament - Short posterior sacroiliac ligament - Interosseous sacroiliac ligament - Sacrotuberous ligament - Sacrospinous ligament ![SI Joint Ligaments](https://3dmusclelab.com/wp-content/uploads/2023/03/si-joint-ligaments.png) While movement is both possible and necessary at the sacroiliac joints, stability is at least as important as movement at these joints. In the move from a four-legged horizontal being to a two-legged vertically oriented being, the work of the sacrum changed in some ways. Compared to a horse, dog, or cat, for example, more of the shock absorption from walking and running is handled by our pelvic girdle, so our SI joints are less mobile. In four-legged animals, some of this shock absorption is managed by the shoulder girdle (Myers, 1998). The many strong ligaments that connect the sacrum to the ilium are critical to creating the necessary pelvic stability, which is one of the main functions of the sacroiliac joints (Ashby et al., 2021; Casaroli et al., 2020). In fact, one reference even refers to the ligamentous connections around the sacrum as a “continuous ligamentous stocking” (Ashby et al., 2021). The ligaments that directly cross the sacroiliac joint, as well as ligaments that connect the sacrum to other sites, change in tension as the sacrum moves. For example, Vleeming, 1996 reported that the long dorsal sacroiliac ligament is slack when the sacrum is in nutation, but is tense when the sacrum is in counternutation. Working in balance with that, the sacrotuberous ligament is slack when the sacrum is in counternutation, but tense when the sacrum is in nutation (Vleeming, 1996). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Movements at the sacroiliac joint Movement at the SI joint is something researchers are still trying to understand. The movement at the sacroiliac joints is multi-dimensional and complex. It’s also quite complicated to measure and scientists have yet to create a really good way of doing that. For that reason, there is still considerable debate about exactly how and how much movement happens there (Klerx et al., 2020). ### Nutation and counternutation The simplest movements that we’re aware of at the sacroiliac joints are referred to as nutation and counternutation. Nutation describes the movement of the sacrum when it nods forward in relation to the ilium bones. Counternutation is the opposite. It describes the movement of the sacrum when it nods backward in relation to the ilium bones. ![SI Joint Movement](https://3dmusclelab.com/wp-content/uploads/2023/03/si-joint-nutation-counter-nutation.png) However, there has been some documented movement at the SI joints in all three directional planes (Casaroli et al., 2020; Vleeming et al., 2012). Movement at these joints varies considerably between individuals. More or less movement is possible depending on bone shape, ligamentous tension or laxity, and muscle tension (Casaroli et al., 2020). However, what’s as important as the idea of the sacrum tilting forward and back, is the idea of the main function of the sacroiliac joints as part of the shock absorption and load transfer system between the torso and the legs (Ashby et al., 2021; Casaroli et al., 2020; Klerx et al., 2020). Sacral movement is not the same thing as the movement of the pelvis at the hip joints, but they are related. How we move each side of our pelvis at the hip joints influences how force is transferred from the legs through the pelvis to the spine above via the sacrum (Ashby et al, 2021). The movement at the sacroiliac joints and their function in force transfer is complicated by the fact that we can move the two sides of the pelvis independently. That’s necessary, of course, for whole-body movement like walking. ## Conclusion The sacroiliac joint is a fascinating, complex part of our human anatomy. Its structure and function are unique among the joints of our body. It’s a critical structure for standing, walking, and running. Due to its location, it’s difficult to study, so much about our understanding of its specific functions remains unclear. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Ashby, K., E. Yilmaz, M. Mathkour, L. Olewnik, D. Hage, J. Iwanaga, M. Loukas, and R.S. Tubbs. 2021. Ligaments stabilizing the sacrum and sacroiliac joint: A comprehensive review. Neurosurgical Review. 8pgs. [https://doi.org/10.1007/s10143-021-01625-y](https://doi.org/10.1007/s10143-021-01625) Casaroli, G., T. Bassani, M. Brayda-Bruno, A. Luca, and F. Galbusera. 2020. What do we know about the biomechanics of the sacroiliac joint and sacropelvic fixation? A literature review. Medical Engineering and Physics. 76:1-12. Enix, D.E. and J.M. Mayer. 2019. Sacroiliac joint hypermobility biomechanics and what it means for health care providers and patients. Physical Medicine and Rehabilitation. 11:S32-S39. Klerx, S.P., J.J.M. Pool, M.W. Coppieters, E.J. Mollema, A.L. Pool-Goudzwaard. 2020. Clinimetric properties of sacroiliac joint mobility tests: A systematic review. Musculoskeletal Science and Practice. 48: 9pgs. [https://doi.org/10.1016/j.msksp.2019.102090](https://doi.org/10.1016/j.msksp.2019.102090) Myers, T. W. 1998. Poise: Psoas-piriformis balance. Massage Magazine, Issue 72, March/April, p.31-39. (Reprinted in Myers, T. W. (March 8, 2022) Body3: A therapist’s anatomy reader. Published by Tom Myers. Richardson, C.A., C.J. Snijders, J.A. Hides, L. Damen, M.S. Pas, and J. Storm. 2002. The relation between the transverse abdominis muscles, sacroiliac joint mechanics, and low back pain. Spine. 27(4):399-405. Vleeming, A., M.D. Schuenke, A.T. Masi, J.E. Carreiro, L. Danneels, and F.H. Willard. 2012. The sacroiliac joint: An overview of its anatomy, function and potential clinical implications. Journal of Anatomy. 221:537-567. Vleeming, A. et al 1996. The function of the long dorsal sacroiliac ligament. Spine. 21(5):556-562. --- Source: https://3dmusclelab.com/scapula/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is The Scapula And What Does It Do? ![Scapula](https://3dmusclelab.com/wp-content/uploads/2019/05/Scapula_plain.png) The body has 206 bones that make up the skeletal system at adulthood. Some of them are the stereotypical bone shape that you might think of if I asked you to picture a bone in the body. You might picture something like the long bone in the thigh, the femur. But there are also lots of bones in unique shapes that contribute to all the variability in movement that we can do. One of these unique bones is the scapula. The scapula is one of the bones that makes up the shoulder complex. We have two of them—one on each side of the upper part of the back. Each bone is roughly triangular-shaped and is important for connecting the arm to the torso. The largest section of the bone is located posterior to the ribcage, but it also has two bony arms that curve around anteriorly and are part of the shoulder girdle. ## Bony landmarks Important bony landmarks on the scapula include: - Acromion - Coracoid process - Spine of the scapula - Superior angle - Inferior angle - Lateral border - Medial border - Supraspinous fossa - Infraspinous fossa - Glenoid cavity ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscles attachments The scapula bone is an important site for muscle attachment. There are 17 muscles that attach to it! These include the following: - Serratus anterior - Supraspinatus - Infraspinatus - Subscapularis - Teres minor - Teres major - Rhomboids major - Rhomboids minor - Levator scapulae - Trapezius - Pectoralis minor - Deltoid - Coracobrachialis - Triceps brachii - Biceps brachii - Latissimus dorsi - Omohyoid The scapulae connect with other bones at the: - Acromioclavicular joint = where the acromion of the scapula meets the clavicle. - Glenohumeral joint = where the humerus meets the glenoid fossa of the scapula. - Scapulothoracic joint (a false joint) = although the scapula “floats” on the ribcage and does not connect with the ribcage in the way that we usually describe bones connecting at a joint, the area where the scapula meets the ribcage is sometimes referred to as the scapulothoracic joint. ## Movements of the scapula What does this curious bone do? The key task of our shoulders is to allow for the wide range of motion that we need to reach, grab, pull, and do all kinds of other things with our arms and hands. At the same time our shoulder girdle needs to be sufficiently stable to support that variety of movement. That’s where the special shape of these bones comes in. Due to their shape, orientation, and the mobility of the joints where they meet other bones, the scapulae have a unique suite of possible movements. They include: - Elevation = moves upward - Depression = moves downward - Retraction (also called adduction) = moves closer to the spine - Protraction (also called abduction) = moves away from the spine and around toward the front of the ribcage - Downward rotation = rotates around a central axis to bring the inferior angle closer to the spine - Upward rotation = rotates around on its central axis to bring the inferior angle away from the spine - Posterior tilt = the medial border lifts off the ribcage The scapulae are unique bones in the body and contribute to the wide range of movements that we can access at the shoulder girdle. It’s an important part of creating the balance between mobility and stability that is critical to functional movement at the shoulder girdle. If you’d like to learn more, check out our article on the [shoulder girdle](https://3dmusclelab.com/shoulder-girdle/). For an even deeper dive, these resources from the National Library of Medicine are a great resource: [https://www.ncbi.nlm.nih.gov/books/NBK531475/](https://www.ncbi.nlm.nih.gov/books/NBK531475/) and [https://www.ncbi.nlm.nih.gov/books/NBK538319/](https://www.ncbi.nlm.nih.gov/books/NBK538319/) The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/exploring-the-spine/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Structures Make Up The Spine? ![Anatomy of the Spine](https://3dmusclelab.com/wp-content/uploads/2020/01/spine-multi.jpg) The spine is a fascinating and important part of our anatomy. Its structure contributes to our upright posture. Functionally, it also houses our spinal cord, a critical part of our central nervous system, which relays all kinds of messages from the brain to the rest of the body. ## Sections and curves of the spine The spine can be divided into sections, each of which has a natural curve, which combine to create its strength and stability. The cervical spine is the section that we know as the neck. This section has a concave curve, which is a curve that goes in towards the body. The thoracic spine is in the area of the mid-back. It has a convex curve, which is a curve that goes out away from the body. The [lumbar spine](https://www.yoganatomy.com/lumbar-spine-in-yoga/) is in the area of the lower back, posterior to the thoracic spine and anterior to the sacrum. It has a concave curve. Finally we have the sacrum, which is the lowest part of the back. It continues on to connect to the coccyx. The sacrum and coccyx together have a convex curve. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Bones in the spine The bones that make up the spine are called vertebrae. There are seven cervical vertebrae that make up the neck section. There are twelve vertebrae in the thoracic section. There are five vertebrae in the lumbar section. The spinal bones could also include the sacrum, which is usually composed of five fused vertebrae, and the coccyx (the tailbone), which is usually composed of four fused vertebrae. ## Joints in the spine Where each of the vertebra meets the next vertebra there are three joints, one on the anterior side and two on the posterior side. The movement at each of these joints adds up to the total available movement that we see in the spine. The joints where each of the vertebra meets the next on the anterior side occur at the vertebral bodies. These anterior intervertebral joints are cartilaginous joints and this is where you find the vertebral discs. The joints where each of the vertebra meets the next vertebra posteriorly, are called the posterior intervertebral joints or facet joints. These are synovial gliding joints which allow the vertebrae to articulate with one another to create small amounts of movement. When we add up each of these small movements, we get the large amount of movement that we see from the spine as a whole. ## Muscles and ligaments around the spine There are several layers of muscles that attach along the posterior vertebrae along most of the spine. At the deepest layer, we find the rotatores which attach from the transverse processes below to the spinous processes above. Each of the small rotatores muscles crosses one or two vertebrae. The rotatores are found only in the thoracic area. The next most superficial layer are the multifidi, which attach primarily from the transverse processes below to the spinous processes above, although the origins of each section of multifidus vary slightly in the lower lumbar area and cervical area. Each section of the multifidus crosses two to four vertebrae. Most superficially, we have the erector spinae group of muscles, which includes iliocostalis, longissimus, and spinalis. Each of those can also be broken down further into sections. When combined, the three sections of each of the iliocostalis, longissimus, and spinalis muscles span the vertebrae from the lumbar spine all the way to the cervical spine. In each area, we find additional muscles that have attachments to the vertebrae there. In the cervical area we also have: - Levator scapulae - Upper trapezius There are several muscles that span both the cervical and thoracic areas: - Splenius capitis - Splenius cervicis - Semispinalis capitis - Semispinalis cervicis In the thoracic area we have: - Rhomboids major - Middle and lower sections of trapezius In the lumbar area we have: - Quadratus lumborum - Psoas major There are also several thick ligaments that help maintain the integrity of the spine. The anterior longitudinal ligament runs along the anterior surface of the vertebral bodies and discs. The posterior longitudinal ligament runs along the posterior surface of the vertebrae. The ligamentum flavum connects the posterior bony wall of adjacent vertebrae. The supraspinous ligament runs along the spinous processes of the vertebrae and becomes the ligamentum nuchae in the cervical area. Finally, the interspinous ligament also connects the spinous processes along the whole spine. ## Movements of the spine Movements of the spine generally include: - Flexion - Extension - Rotation - Lateral flexion or side-bending There is more or less movement of each of these types in different sections of the spine. The amount of movement in a particular direction is affected by the shape of the vertebrae in that section and how they fit together. In the cervical spine, we can see lots of movement in all of these directions. In the thoracic spine, due to the shape of the vertebrae, there is more rotation available than in the lumbar spine and less movement available in the direction of flexion and extension. In the lumbar spine, due to a slightly different shape of the vertebrae, there is more movement in the flexion and extension direction than we find in the thoracic spine, but less rotation is available. If you’d like to learn more about some important muscles that move the spine, check out our article on the [erector spinae muscles](https://3dmusclelab.com/erector-spinae-muscles/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/hand-and-wrist-anatomy/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Bones, Joints, And Muscles Of The Hand And Wrist ![Hand and Wrist Anatomy](https://3dmusclelab.com/wp-content/uploads/2020/01/wrist-anatomy.jpg) Our hands and wrists are often parts of our anatomy that we take for granted, until something starts to hurt or dysfunction. We use them for fine movements like writing and for more gross movements like picking up objects or holding the steering wheel. We even use our hands and wrists to support us in weight-bearing in sports like gymnastics or activities like [yoga](https://www.yoganatomy.com/wrist-pain-in-yoga/). Whether we’re interested in hand and wrist function or whether we’re concerned about dysfunction, it’s important to remember that the hand and wrist don’t exist in isolation. They’re located at the end of a functional chain of joints which begins at the shoulder and includes the elbow in the middle of that chain. Let’s take a look at what bony structures and joints make up hand and wrist anatomy. We’ll start with the most proximal structures and then make our way distally. ## Joints of the wrist and hand Most proximally, we have the distal radioulnar joint. This is where the distal ends of the radius and ulna rotate around one another to allow for pronation and supination of the forearm. Next, we come to the “true wrist joint.” This is an ellipsoidal joint where the distal end of the radius meets three of the four proximal [carpal bones](https://3dmusclelab.com/carpal-tunnel-syndrome/) (they are the scaphoid, lunate and triquetral bones). Following that, we come to the joints where the four proximal carpal bones then meet the row of four distal carpal bones. Next in line, as we go distally, are the five metacarpals. These five metacarpal bones articulate at five joints (our knuckles) with our five proximal phalanges. Along with our other phalanges, we then have what are otherwise known as our fingers. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Movements at the wrist joint Movements at the wrist all have more than one name. - Flexion of the wrist is also called palmar flexion. - Extension of the wrist is also called dorsi flexion. - Ulnar deviation is also referred to as adduction. - Radial deviation is also referred to as abduction. All of these movements combined will give us circumduction of the wrist. ## Muscles of the hand and wrist There are many muscles that make up the hand and wrist. We won’t try to list every single one here. Muscles of the hand and wrist can more generally be grouped into wrist flexors, wrist extensors, and muscles that move the fingers and/or thumb. Keep in mind that, of course, some muscles contribute to more than one action. ## Wrist flexors - Palmaris longus - Flexor carpi radialis - Flexor carpi ulnaris - Flexor digitorum superficialis - Flexor digitorum profundus - Flexor pollicis longus ## Wrist extensors - Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor digitorum - Extensor digiti minimi - Extensor pollicis brevis - Extensor indicis - Extensor carpi ulnaris ## Muscles that move the fingers and/or thumb - Abductor pollicis longus - Extensor pollicis brevis - Extensor indicis - Opponens pollicis - Flexor pollicis brevis - Adductor pollicis - (And some other small muscles which we will not list here.) ## Conclusion We use our wrists and hands for so many necessary daily activities. And even the simple things we do with our hands require a complicated interaction of multiple muscles. This long list of wrist flexors, wrist extensors, and muscles that move the fingers and thumb combine to allow us to do all of the many types of movement that we do with our hand and wrist. Next time you type on a keyboard or send a text message, think about how many muscles you’re using! If you want to learn more about the anatomical structures in the body, where they’re located, and how they move, check out our recent posts! The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscle-contractions/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Muscle Contractions: How Do Muscles Work? ![muscle contractions](https://3dmusclelab.com/wp-content/uploads/2019/02/muscle-contractions.jpg) Before we dive into muscle contractions, we looked at the anatomy of a skeletal muscle in our article, [What Is A Muscle?](https://3dmusclelab.com/what-is-a-muscle/) As a reminder, in addition to skeletal muscles which are the kind of muscles that move bones, we have two other kinds of muscle tissue: cardiac muscle and smooth muscle. Cardiac muscle tissue is found in the heart. Smooth muscle tissue is found in places where involuntary action is needed, for example, in our arteries and visceral organs. When we delve further into types of muscle contractions in this post, we’ll be referring to the types of contractions that are primarily relevant to skeletal muscles. So, we have an idea of what a skeletal muscle is, but how does it do its work? ## Muscle contractions The action of a muscle is called a contraction. On a cellular level, when muscle activity is needed, the nervous system sends a message to a muscle cell or cells and tells them to act, to contract. Not all of the cells in a single muscle contract at the same time to create the action called for by the nervous system. Only the number of muscle cells actually needed for the action will contract at one time. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Types of muscle contractions Our muscles can do different types of contractions depending on the kind of muscle activity that the body needs. Muscles can move bones to create movement, of course, but they can also act to resist movement, or stabilize an area of the body. These different kinds of activity require different kinds of muscle contractions. ### Tonic contraction The word ‘tonic’ means tone. Tonic muscle contractions then are simply the contractions that maintain the resting tone of our muscles. ### Isometric contraction The word ‘isometric’ means same length. Isometric muscle contractions occur when the tension or tone of the muscle changes, but the length of the muscle stays the same. For example, if we pick up a rock and carry it around in our hand out in front of us, several muscles are doing an isometric contraction to resist gravity and keep the rock steady in our hand. ### Isotonic contractions – concentric and eccentric The word ‘isotonic’ means same tone. Isotonic muscle contractions occur when the tension of the muscle stays the same, but the length of the muscle changes. There are two types of isotonic contractions. In an isotonic concentric contraction the muscle gets shorter while contracting. This is the idea of muscle contraction that we are usually most familiar with. For example, my biceps brachii will do an isotonic concentric contraction when I lift a glass of water from the table and bring it toward my mouth. There is another type of isotonic contraction, however. We also experience isotonic eccentric contractions. In this type of contraction the muscle is getting longer while the tension remains the same. For example, if I bend over to pick something up from the floor, my hamstrings will do an isotonic eccentric contraction. They will get longer as they resist gravity to slow my momentum and allow me to reach to the floor with some control. ## Conclusion Have a play with identifying muscle contractions in your own body. If you’re a yoga practitioner, check out this example of how [muscle contractions are relevant](https://www.yoganatomy.com/muscle-contraction-in-yoga/) to your yoga practice. As you’re moving about your day, think about which muscle actions are required to do the tasks you’re doing. Which muscles are doing isotonic concentric contractions? Which muscles are doing isotonic eccentric contractions? Are there also muscles doing isometric contractions in that same action? The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscular-actions-breathing/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Muscular Actions Of Breathing: What Happens When We Breathe? ![Muscular Actions of Breathing](https://3dmusclelab.com/wp-content/uploads/2025/04/diaphragm-breathing.jpg) Breathing is both an unconscious, or involuntary, action that we rely on to function seamlessly in the background, as well as a process that we can consciously steer. If we take up certain kinds of sports, like swimming or running, for example, we will have to learn to control how we breathe. But, it would definitely be problematic if we had to think about the essential task of breathing all the time. So what happens when we breathe? How does it work? In this article, we’ll take a look at the process of breathing and the muscles we use. ## What is breathing? Breathing happens when air moves in and out of the lungs. The technical term for that process is pulmonary ventilation. It happens when we inflate and deflate our lungs. There are many phrases used to describe different [techniques for breathing](https://www.yoganatomy.com/breathing-in-yoga-is-there-a-right-and-wrong-way/) during specific types of exercise or during specific practices to reduce the stress response, for example. However, no matter what kind of technique we employ, we breathe by inflating and deflating our lungs to draw oxygen-rich air in and push carbon dioxide-containing air out. There are two phases to regular breathing: inhalation and exhalation. Inhalation is also called inspiration. Exhalation is also called expiration. Changes in pressure outside and inside the lungs create the air exchange that we call breathing. However, the lungs are passive. The lungs are not muscles, so we have to use other muscles to manage the exchange of pressure to move air in and out of our lungs. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscles of regular breathing The diaphragm is the main muscle of respiration in regular breathing. However, two other muscles assist the actions of inspiration and expiration, the external and internal intercostals. ### Diaphragm The diaphragm is a particularly unique muscle. It attaches broadly in what is considered its origin to the lumbar vertebrae L1-L3 (and sometimes L4), the lower six costal cartilages, and the posterior surface of the xiphoid process. Then, it inserts onto itself at what is called the central tendon. ### Intercostal muscles The intercostal muscles are found between the ribs. You could understand their location from their name. The prefix “inter” means between. The word “costal” means rib. The external intercostals originate on the inferior (lower) border of the rib above and insert on the superior (upper) border of the rib below. As their names might suggest, the internal intercostals are deep to (underneath) the external intercostals. They originate on the inner border of the rib above and insert on the superior border of the rib below. ## Process of regular breathing In regular breathing, sometimes called “quiet breathing” or “breathing at rest,” as we inhale, the top of the diaphragm descends and flattens out somewhat. That action pulls on the connective tissue connection to the lungs. Simultaneously, the external intercostals contract and help lift the ribs up and out. During an inhale, there is a negative pressure in the lungs. Because the air outside the lungs is at a higher pressure, it gets drawn into the area of lower pressure in the lungs. Then, as we exhale, the diaphragm relaxes and lifts up. The external intercostals also relax, allowing the ribcage to come in and down. The internal intercostals can also add some amount of contraction (depending on the intensity of our breathing) to assist in bringing the ribs down and in. When we are breathing at rest, exhalation is mostly a passive part of the breathing cycle. The elastic recoil of the tissues, as well as the change in the pressure difference inside and outside the lungs, pushes the air out. ![Breathing Process](https://3dmusclelab.com/wp-content/uploads/2025/04/diaphragm-respiration.jpg) ## Secondary respiration In some situations, during intense exercise for example, the muscles we recruit to inhale and exhale may differ. Additional muscles, called secondary respiratory muscles, are called into action when our breath is forced or when we have an increased need for more oxygen more quickly. That might include something short and acute, like a cough or sneeze, or a moment when we’ve abruptly knocked the primary breathing action offline (like falling or getting knocked down in sports). It could also be a situation where we have a more sustained need, like running, for more breath more quickly. The main additional muscles incorporated in secondary respiration include the [sternocleidomastoid, the three scalene muscles](https://3dmusclelab.com/neck-muscles-superficial/), and the four layers of [abdominal muscles](https://3dmusclelab.com/abdominal-muscles/) (rectus abdominis, internal and external obliques, and transverse abdominis). When we need to get more air in more quickly, the sternocleidomastoid and scalene muscles help lift the ribcage up. Simultaneously, the intercostals lift the ribcage up and out to make space for an inhale. During a forced exhalation, like a cough or a sneeze for example, all four layers of abdominals contract along with the internal intercostals to push the air out. ## Conclusion Breathing is an essential process that is both voluntary and involuntary. We use muscular action to influence the pressure difference inside and outside of our lungs. That has the effect of either drawing air in or forcing air out. The diaphragm is always part of the action of breathing, but we may also recruit other secondary breathing muscles, depending on how much we are exerting ourselves. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2008. Chapter 14: The Thorax. In Clinical Application of Neuromuscular Techniques. Volume 1 – The Upper Body (Second Edition). New York, NY: Churchill Livingstone Publishing. [Travell, J.G. and D.G. Simons. 1999. Chapter 45: Intercostal Muscles and the Diaphrgam. In Myofascial Pain and Dysfunction – The Trigger Point Manual. Volume 1 (second Edition). New York, NY: Lippincott, Williams, and Wilkins Publishing.](https://bookshop.org/p/books/travell-simons-simons-myofascial-pain-and-dysfunction-the-trigger-point-manual-joseph-m-donnelly/499920?ean=9780781755603&next=t) --- Source: https://3dmusclelab.com/rotator-cuff-muscles-shoulder-pain/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Rotator Cuff Muscles And Shoulder Pain – Why Does It Happen? ![Rotator Cuff And Shoulder Pain](https://3dmusclelab.com/wp-content/uploads/2023/08/rotator-cuff.jpg) Shoulder pain is a relatable experience for many people. And, one of the most common sources of that pain is dysfunction or injury of the rotator cuff muscles. In this article, we’ll take a look at why that muscle group is so often associated with shoulder pain. ## What and where are the rotator cuff muscles? Before we dive into shoulder pain, let’s take a moment to review this muscle group. Remember that we have four [rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles/): subscapularis, infraspinatus, teres minor, and supraspinatus. All four of these muscles attach to the [scapula](https://3dmusclelab.com/scapula/) at one end and the humeral head on the other end. The tendons of these muscles all come together and form a cuff around the humeral head which is where the group gets its name. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the actions of each of the rotator cuff muscles? Each of the rotator cuff muscles has a specific primary action. Remember that the subscapularis does medial rotation of the humerus. The supraspinatus initiates abduction of the humerus. And, infraspinatus and teres minor do lateral rotation of the humerus. However, although every anatomy book lists specific actions that these muscles do when they [concentrically contract](https://3dmusclelab.com/muscle-contractions/), one of their most important actions is actually stabilization. They work together as a group to stabilize the humeral head in the glenoid fossa from multiple directions. For example, subscapularis helps stabilize the humeral head and resists anterior translation. Infraspinatus and teres minor balance that. They stabilize the humeral head and resist posterior translation. With that in mind, we could consider that a primary [“job” of the rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles-and-movement/) is to stabilize the humeral head in the socket so that we can use our arms and hands to do fine motor movements. Each of the four muscles on its own is a relatively small muscle. They act as synergists alongside more powerful prime movers rather than initiating big movements themselves. ## Why are healthy rotator cuff muscles so important? The socket (called the glenoid fossa) where the head of the humerus inserts to form the shoulder joint, is shallow. It takes muscles, ligaments, and tendons all under the right balance of tension to hold the head of the humerus in the socket and keep the joint functional. Any injury or strain in one muscle of the rotator cuff will affect the stability and balance of the whole shoulder joint. ## Why are the rotator cuff muscles so often a cause of shoulder pain? ### Overuse Many sources note that rotator cuff tendonitis is the most common cause of shoulder pain. But why is that? There are a few reasons. One simple reason is overuse. We do a lot of activities at work, at home, and for leisure that use our shoulders in repetitive ways. Remember that the whole [shoulder complex](https://3dmusclelab.com/shoulder-girdle/), including the shoulder joint specifically, is very mobile. This allows us to do all kinds of things including specific fine movements with our [hands](https://3dmusclelab.com/hand-and-wrist-anatomy/) and [arms](https://3dmusclelab.com/elbow-joint-and-forearm/). But, it also makes it easy to overdo it when we use these muscles. Repetitive use can lead to inflammation, irritation, or injury of these muscles. ### Imbalance Repetitive motions from work activities or sports can also cause an imbalance in the tension held between the different rotator cuff muscles. And, another very common cause of shoulder pain is an imbalance of tension between the those muscles. That can put strain on the shoulder joint and result in [pinched nerves](https://3dmusclelab.com/brachial-plexus/), pressure on a bursa, or just generally irritated [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Muscles don’t work in isolation, so an imbalance between other [agonist and antagonist muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) can also result in an imbalance in the tension of the rotator cuff muscles. Additionally, the position of the shoulder is related to the position and tension of structures in the larger kinetic chain. So, the location of the torso, ribcage, [spine](https://3dmusclelab.com/exploring-the-spine/), etc. also influences the position of the shoulder joint, and indirectly they influence the tension in the rotator cuff muscles. ### Using a small muscle for a big job Using the rotator cuff muscles for actions they’re not well-suited for can also result in shoulder pain and injury. The classic case is suddenly lifting a heavy suitcase and tearing supraspinatus. In fact, supraspinatus is the most common muscle of the rotator cuff group to get injured. It’s sometimes even referred to as the “suitcase muscle.” This is because of its association with getting irritated when we suddenly pick up a heavy suitcase and ask this muscle to do more work than it’s cut out for. However, any and all of the four rotator cuff muscles and their associated tendons can get injured if we use these muscles for big actions that they’re not well-placed or sufficiently large to handle. ### Other causes Acute trauma to either soft tissue or the bones of the shoulder can of course also cause injury to one or more of the rotator cuff muscles and cause shoulder pain. And age-related wear and tear of this muscle group can contribute to shoulder pain as well. Finally, the genetics that inform how everything comes together at your shoulder joint can affect the likelihood of experiencing rotator cuff-related shoulder pain. For instance, you may have less space below the acromion potentially creating a higher likelihood of compression, bursitis, fraying of the supraspinatus tendon, and even bone spurs. ## Types of rotator cuff-related shoulder injury and dysfunction Depending on the location and cause of the rotator cuff issue, there are different types of injuries and dysfunction that can result. The specific diagnosis of each of these dysfunctions should be handled by a medical professional and is far beyond the scope of this article. Generally, issues with these muscles could include: - Rotator cuff tendonitis - Partial thickness tear - Full thickness tear - Subacromial impingement syndrome - External impingement syndrome - Others ## Symptoms of rotator cuff-related pain Rotator cuff-related shoulder pain might show up as: - General shoulder aches and pain - Pain when doing repetitive tasks with the shoulders - Shoulder pain while lying on the shoulder when sleeping - Shoulder muscle weakness or weakness when [moving the shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/) - Additionally, there are many orthopedic tests for specific rotator cuff muscle dysfunction that are beyond the scope of this article ## Treatments for rotator cuff-related shoulder pain Treatments depend on each specific situation. If you have shoulder pain or suspect rotator cuff issues, you should consult with an appropriate medical professional for an assessment. Initial treatments for mild tendonitis might involve taking a break from activities that overuse your shoulders in a particular way. Ice and rest can often help reduce inflammation. If the issue is caused by a muscular imbalance, then an experienced physical therapist or bodyworker may be able to help. Appropriate stretching and strengthening exercises are often suggested to address the underlying causes behind mild tendonitis or small tears. In the case of more significant tears or acute trauma to the rotator cuff, surgery might be necessary. ## Conclusion There are many reasons why we might strain or injure a rotator cuff muscle. That makes this area one of the most common sources of shoulder pain. The balance of tension between these four muscles is important for maintaining a full range of motion of the shoulder. If one rotator cuff muscle is injured, it affects the kinematics of the whole shoulder. So there are also lots of good reasons for giving this area some extra care in order to maintain a healthy rotator cuff. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Horsley, I. 2005. Assessment of shoulders with pain of a non-traumatic origin. Physical Therapy in Sport. 6:6-14.](https://www.sciencedirect.com/science/article/abs/pii/S1466853X04001245) [Kolk, A., J.F. Henseler, P. Bas de Witte, E.W. van Zwet, P. van der Zwaal, C.P.J. Visser, J. Nagels, R.G.H.H. Nelissen, J.H. de Groot. 2017. The effect of a rotator cuff tear and its size on three-dimensional shoulder motion. Clinical Biomechanics. 45:43-51.](https://pubmed.ncbi.nlm.nih.gov/28477525/) [Malcarney, H.L. G.A.C. and Murrell. 2003. The rotator cuff: Biological adaptations to its environment. Sports Medicine. 33(13):993-1002.](https://pubmed.ncbi.nlm.nih.gov/14606926/) [Rathi, S., N.F. Taylor, B. Soo., and R.A. Green. 2018. Glenohumeral joint translation and muscle activity in patients with symptomatic rotator cuff pathology: An ultrasonographic and electromyographic study with age-matched controls. Journal of Science and Medicine in Sport. 21:885-889.](https://pubmed.ncbi.nlm.nih.gov/29525201/) [Varacallo M., Y. El Bitar, S.D. Mair. 2023. Rotator Cuff Tendonitis. [Updated 2023 Aug 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532270/](https://www.ncbi.nlm.nih.gov/books/NBK532270/) --- Source: https://3dmusclelab.com/the-complex-low-back/ Author: David Keil · Updated: 2026-05-21 Anatomy And Physiology # The Complex Low Back ![The Complex Lower Back](https://3dmusclelab.com/wp-content/uploads/2026/03/low-back.jpg) The low back is a frequent source of complaints. Pain, tension, and dysfunction in the lower back area are all common reports heard by doctors, physical therapists, and bodyworkers. So, why is this area of our body such a magnet for discomfort? In this article, we’ll explore the answer to that question. We’ll look closer at the anatomy of the low back, how it comes together, and see why it could complicate movement and posture. ## What is the low back? There is no official anatomical region called the lower back. Different people may mean different things when they say low back. Generally, though, if we refer to the low back, we would include the tissues and structures within the lumbosacral region. That is, all the tissues and structures on and around the lumbar spine and sacrum. ### Bones The lumbar area of the spine spans a section of five vertebrae from L1 to L5. The sacrum is a single triangular bone just inferior to the lumbar [spine](https://3dmusclelab.com/exploring-the-spine/). When we’re young, the bones that eventually fuse to become the sacrum are five individual [vertebrae](https://3dmusclelab.com/herniated-bulging-and-ruptured-vertebral-discs/). The most inferior of the lumbar vertebrae, L5, articulates with the top of the sacral bone. On each side, our sacrum articulates with the two sides of our [pelvis](https://3dmusclelab.com/exploring-the-pelvis/), where the sacrum meets the ilium at the sacroiliac joints. These bony structures and the soft tissue that connects to them loosely define the area that we might consider our lower back. ### Muscles Most superficially, we have the [erector spinae muscles](https://3dmusclelab.com/erector-spinae-muscles/) and the thoracolumbar aponeurosis. Deep to the erector spinae and attaching to the vertebrae, you’ll find the transversospinales group, including the multifidus and rotatores. Those [muscles](https://3dmusclelab.com/muscle-contractions/) are often considered part of our core because they are located deep in the body. They are found right up along the spine. Also attached to the lumbar vertebrae are the [quadratus lumborum](https://3dmusclelab.com/quadratus-lumborum-muscle/) and [psoas major](https://3dmusclelab.com/palpating-your-iliopsoas-muscle/), two more muscles that are part of our core. More inferior in the low back region, we have [piriformis](https://3dmusclelab.com/piriformis-muscle/), [gluteus maximus](https://3dmusclelab.com/gluteus-maximus/), the coccygeus muscles, and some fibers from the iliacus, which all attach to the sacrum. The low back is a [criss-cross of muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) and associated fascia in several layers and reaching from all directions. Some muscles on the front of our body reach around to the low back or have indirect fascial connections to the lower back. Muscles like the [internal and external obliques](https://3dmusclelab.com/abdominal-muscles/) and the [transverse abdominis](https://3dmusclelab.com/abdominal-muscles/) don’t attach directly to the lumbar spine or sacrum, but could still contribute to a pull on that area indirectly. This is one reason that the low back can show up as an area where we feel pain or tension, even if the source of that tension is not in the lower back itself. This is why tight abdominals can create compression of the discs by reducing the lumbar curve. Or, a [tight psoas muscle](https://3dmusclelab.com/the-iliopsoas-related-to-back-pain/) can contribute to an increased lordotic curve and an anterior pelvic tilt. Even tension from muscles on the side, such as obliques, can contribute to hiking up a hip or pulling one side of the rib cage down. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Actions in the low back Movement in the area of the low back happens in the [spine](https://3dmusclelab.com/muscles-affected-in-scoliosis/), the sacroiliac joints, and to some degree, at the hip joints. The available directions and amount of [movement](https://3dmusclelab.com/functional-movement/) at each of these joints influence what kind of movement is or is not available to us. The [sacroiliac joints](https://3dmusclelab.com/sacroiliac-joint/), or SI joints, are small, uniquely shaped joints that do only a tiny amount of movement. The hip joints, of course, are ball-and-socket joints that allow the pelvis to move in many directions over our legs. The bone shape of the lumbar vertebrae and the specific way that they glide at the facet joints make the lumbar spine flex and extend much more easily than side-bend or twist. ## What influences ease of movement in our lower back? By looking at all the directions of pull on the low back from the [muscles](https://3dmusclelab.com/muscles-when-we-age/) we’ve covered and the influence in all directions by multiple sets of joints that move this area, you get a sense of how complex this area really is. All of these structures and tissues influence movement and [tension](https://3dmusclelab.com/sitting-posture/) in the lower back. You could think of the low back like the section of a big city where multiple interstate highways intersect. There are roads going in every direction, lanes beginning and ending at various points, and multiple on and off-ramps that appear along the way. The combination of all of these potential interactions allows for both the adaptability of this area where our lower and upper body meet. It also creates a seemingly endless potential for compensations if any parts of this whole are tight, injured, or dysfunctional. The balance of muscle tension between all the different muscles and their associated fascia affects the ease of movement in the low back. And, although there are muscles crossing the low back and supporting it from multiple directions, movement is also restricted by the available movement at the joints in this region. The interrelationship between what kind of movement the joints allow and the tension of the myofascia that further allows or restricts movement leads to the kind of complex situation we have at the low back. ## Conclusion There are many possible reasons for pain and dysfunction in the lower back. The specific details are out of the scope of our topic here. In the big picture, the complex situation created by the number of muscles, joints, and other myofascial structures that relate to each other in the low back makes it vulnerable to potential compensations and dysfunction. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/deep-six-lateral-rotators-movement/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # The Deep Six Lateral Rotators And Movement ![Deep Six Lateral Rotators And Movement](https://3dmusclelab.com/wp-content/uploads/2023/06/deep-six.jpg) The group of muscles commonly referred to as the [deep six lateral rotators](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) of the hip is a fascinating group. But, this may not be a group of muscles that you’ve heard much about. These muscles are an important group for understanding [pelvic movement](https://3dmusclelab.com/exploring-the-pelvis/). They contribute to a surprising variety of hip actions. So in this article, we’ll take a closer look at these six muscles and [what movements](https://3dmusclelab.com/functional-movement/) they contribute to. ## What muscles are included in this group? To review, this group of muscles includes: - [Piriformis](https://3dmusclelab.com/piriformis-muscle/) - Gemellus superior - Gemellus inferior - Obturator internus - Obturator externus - Quadratus femoris All of the deep six lateral rotators attach to ([originate on](https://3dmusclelab.com/muscle-origin-insertion-and-action/)) various locations on the ischium of the pelvis with the exception of the piriformis muscle. The piriformis originates on the anterior side of the sacrum. All of the deep six lateral rotators attach to (insert on) various locations of the greater trochanter of the femur at their other end. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## How do the deep six lateral rotators contribute to movement? In my previous article, I discussed some of the specific actions that these muscles do or assist with. And I also mentioned that these muscles are deep to the large gluteus maximus. Their location, deep to a very dense muscle like gluteus maximus, makes it more difficult to determine when the deep six lateral rotators are activated during particular motions with tools like electromyography (EMG). So, there is still some exploring to do to fully understand the ways that this group of muscles function during different types of activities. Aside from lateral rotation of the thigh, individual researchers and anatomists list different possibilities with respect to which additional actions these six muscles may contribute to. ### Bilateral actions One thing that it’s important to consider is whether both hips are moving together (bilaterally) or whether we’re describing actions of one hip only (unilateral action). This can change what action these muscles create. When we activate this group of muscles on both sides at the same time (bilateral action), they can contribute to extending the hip joint. If we were in a position where both legs were free to lift (an open chain position), maybe something like a locust pose in yoga, or alternating prone extensions, then the deep six lateral rotators could contribute to extending our legs at the hip joint. However, if we were standing on both feet (a closed chain position) and bilaterally activated these muscles, then they could contribute to posteriorly tilting the pelvis relative to the legs. Of course, [muscles don’t just initiate action](https://3dmusclelab.com/muscle-contractions/), they also [resist opposing muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) and actions. So we could also consider that this group of muscles, acting bilaterally, assists with resisting or opposing all the muscles that flex the hip joint. Myers, 2014 suggests we could even think of these muscles as “extensori coxae brevis,” or the short hip extensors, rather than “lateral rotators.” ### Unilateral actions If we look at unilateral actions, then we mean that one side of our pelvis is doing something different from the other side. The most straightforward movement that all six of these muscles contribute to is the one they’re named for, lateral rotation. They laterally rotate one leg at the hip joint when you’re standing, but not weight-bearing with that leg. But how often do we actually stand on one leg and then laterally rotate the other one? This might come up for the dancers reading this, but not so often for the rest of us. What’s more likely is that we all walk. And these muscles contribute to laterally rotating one hip as we take a step (Myers, 2014). But, just like I discussed with respect to the contributions of this muscle group to posterior pelvic tilt, when we change our ideas of origin and insertion, we can see that these muscles as a group could also move the pelvis around the leg. ### Other movements As I’ve already alluded to, how the deep six lateral muscles act in movement depends on the position of the body. It’s important that we remember that our body is three-dimensional! For example, Chaitow and DeLany, 2011 refer to a “piriformis paradox.” In open chain, unilateral movement, the piriformis does lateral rotation of the thigh when the hip joint is extended or flexed less than about 60 degrees. But, he suggests that when the hip is flexed more than 60 degrees, piriformis can actually contribute to internal rotation (Chaitow and DeLany, 2011). Similarly, Yoo et al., 2015 and Chaitow and DeLany, 2011 both report that obturator internus, gemellus superior, and gemellus inferior all contribute to abduction of the thigh when the hip is flexed. ## Conclusion While we might have an idea that everything is already known about human anatomy and how our muscles work, this is often far from true. The human body is fascinatingly complex. And, there is a lot we still don’t know about what’s happening with our muscles when we move. Our deep six lateral rotators are one of those groups of muscles that we are learning more about. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Chaitow, L. and J. DeLany. 2011. The Hip. In Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition).](https://www.sciencedirect.com/book/9780443068157/clinical-application-of-neuromuscular-techniques) [Myers, T., 2014. ‘The Deep Six, Part 1’ In The Anatomist’s Corner: Issues in Structural Anatomy. pgs.157-162.](https://www.anatomytrains.com/product/the-anatomists-corner/) [Yoo, S., I. Dedova, and N. Pather. 2015. An appraisal of the short lateral rotators of the hip joint. Clinical Anatomy. 28:800-812.](https://pubmed.ncbi.nlm.nih.gov/26032283/) --- Source: https://3dmusclelab.com/sternoclavicular-and-acromioclavicular-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # The Sternoclavicular And Acromioclavicular Joints: Completing The Shoulder Complex ![Sternoclavicular and Acromioclavicular Joints](https://3dmusclelab.com/wp-content/uploads/2025/01/shoulder-complex.jpg) Our [shoulder complex](https://3dmusclelab.com/shoulder-girdle/) has a tricky job of [allowing movement](https://3dmusclelab.com/shoulder-joint-in-movement/) in all directions while also maintaining sufficient stability. Many structures come together to form the larger shoulder complex and make this amazing balance of mobility and stability possible. It takes the coordination of all the structures at the shoulder complex to experience a full range of functional movement. We’ve already covered the glenohumeral joint, which is the true shoulder joint. There are two other joints that work with the glenohumeral joint to make up the shoulder complex, the sternoclavicular joint and the acromioclavicular joint. In this article, we’ll take a look at those joints to complete our picture of the shoulder complex. Read on to learn where these joints are located, what muscles cross them, and what actions they do. ## What structures make up the sternoclavicular and acromioclavicular joints? ### Bones The sternoclavicular joint includes two bones, the sternum (breast bone) and clavicle (collar bone). As the name suggests, the joint is where the sternum articulates with the clavicle. Specifically, it’s where the medial end of the clavicle meets the manubrium (superior end) of the sternum. Additionally, there is a connection that completes this joint surface between the costal cartilage of the first rib and the manubrium of the sternum. The sternoclavicular joint is where the appendicular skeleton (your arm) connects to the axial skeleton. The acromioclavicular joint is the joint at the other end of the clavicle. It includes two bones, the lateral end of the clavicle and the acromion. The acromion is the bony shelf that juts off the front of the scapula (the shoulder blade). It hangs over the head of the humerus where it articulates with the glenoid fossa of the scapula to create the shoulder joint itself. ### Joint type The sternoclavicular joint is a multiaxial saddle-shaped gliding [synovial joint](https://3dmusclelab.com/synovial-joint/), with a fibrocartilage disc. The acromioclavicular joint is a multiaxial plane-type gliding synovial joint. ### Ligaments There are four [ligaments](https://3dmusclelab.com/ligaments-and-tendons/) that cross the sternoclavicular joint. They are the anterior sternoclavicular ligament, posterior sternoclavicular ligament, costoclavicular ligament, and the interclavicular ligament. These strong ligaments are an important part of stability at the joint. This joint is a key connection for connecting the appendicular skeleton ([arm](https://3dmusclelab.com/elbow-joint-and-forearm/)) to the axial skeleton, but there aren’t any muscles that cross this joint. The ligaments then are essential to maintaining the necessary stability. The acromioclavicular joint is stabilized by two pairs of ligaments. The first pair includes the conoid and trapezoid coracoclavicular ligaments. The second pair includes the superior and inferior acromioclavicular ligaments. As with the sternoclavicular joint ligaments, the ligaments at the acromioclavicular joint are essential for keeping this uniquely shaped joint connected and stable. ### Muscles No [muscles](https://3dmusclelab.com/what-is-a-muscle/) directly cross the sternoclavicular or acromioclavicular joints and move them (like you might think of with a muscle like the biceps brachii). Instead, movement is caused indirectly. Six muscles attach to the clavicle. Those are the deltoid, pectoralis major, [trapezius](https://3dmusclelab.com/trapezius-muscle/), [sternocleidomastoid](https://3dmusclelab.com/neck-muscles-superficial/), and the subclavius muscle. [Muscle contractions](https://3dmusclelab.com/muscle-contractions/) by any of the muscles that attach to the clavicle can affect movement at the joints at either end of the clavicle. Movement at the sternoclavicular joint and the acromioclavicular joint are also intimately related to movements of the scapula. Movements of the [scapula](https://3dmusclelab.com/scapula/) by muscles that don’t attach to the clavicle, like the rhomboids, serratus anterior, or [rotator cuff group](https://3dmusclelab.com/rotator-cuff-muscles/) will still be reflected in movements at the sternoclavicular and acromioclavicular joints. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Movements at the sternoclavicular and acromioclavicular joints As you’ve learned already, there are similarities in the structure of the sternoclavicular and acromioclavicular joints. However, the [range of movement](https://3dmusclelab.com/muscle-origin-insertion-and-action/) created at each is significantly different. The movements at the acromioclavicular joint would be measured in millimeters. At the sternoclavicular end of the clavicle, the joint surfaces don’t necessarily move far, but enough that the distal end of the clavicle can be moved by inches. Both the sternoclavicular and acromioclavicular joints allow for elevation and depression movements. Both joints also do protraction and retraction movements. While they both also do a rotational movement, however, their directions of rotation are different. The sternoclavicular joint can do rotation about its own axis, or in the sagittal plane. The acromioclavicular joint, however, can rotate in a lateral and medial direction, or in the transverse plane. ## What about the scapulothoracic joint? There is another relationship that should be included to complete our picture of the shoulder complex. It’s sometimes referred to as the scapulothoracic joint. However, the scapulothoracic joint is not a true joint. It’s not an articulation between bones. The term scapulothoracic joint is a misnomer that is sometimes used to describe the movement of the scapula in the [myofascial sling](https://3dmusclelab.com/what-is-muscle-fascia/) that connects the scapula to the posterior side of the ribcage. The tension and movement at the scapulothoracic junction will certainly affect the position and movement of both the acromioclavicular and the sternoclavicular joints. So, the positional relationship between the scapula and the thorax is an important part of our whole shoulder complex. However, it’s important to understand that this connection is not a true joint, so the way that movement happens there is different than it is where two bones articulate. ## Conclusion The shoulder complex is, as its name suggests, a complicated interaction of structures. When all of these parts work together, we experience an amazing variety of available movement. Understanding the individual parts that make up the shoulder complex can help us understand its function as a whole. The sternoclavicular and acromioclavicular joints are key parts of what makes our shoulder complex work. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 13: Shoulder, arm, and hand. In Clinical Application of Neuromuscular Techniques. Volume 1 – The Upper Body (Second Edition). New York, NY: Churchill Livingstone Publishing. [Dhawan R., R.A. Singh, B. Tins, and S.M. Hay. 2018. Sternoclavicular joint. Shoulder Elbow. Oct:10(4):296-305.](https://pmc.ncbi.nlm.nih.gov/articles/PMC6134528/) [Wong M. and J. Kiel. 2025. Anatomy, shoulder and upper limb, acromioclavicular joint. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499858/](https://www.ncbi.nlm.nih.gov/books/NBK499858/) --- Source: https://3dmusclelab.com/anatomical-terms-location-position/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Understanding Anatomical Terms For Location And Relative Position ![Anatomical Terms For Body Location And Relative Position](https://3dmusclelab.com/wp-content/uploads/2024/10/anatomical-terms.jpg) If you work with students or clients in a body-centered practice like yoga, Pilates, physical therapy, or personal training, then you know how important it is to be able to communicate about what you see and feel in someone’s body. For that reason, anatomists, medical practitioners, and others have developed a shared anatomical language to describe the location and relative position of structures in the body. This terminology helps us be specific and consistent about what we’re describing. Bodies are complicated. Using agreed upon anatomical terms helps us be clear in our communication about the complexity we’re describing. In this article, I’ll take you on a tour of the anatomical terms used to describe the location and relative position of structures in the body. ## Describing position and location in the body When we use positional anatomical terms, we commonly use them in one of two ways. We might refer to something in the body by its general location, for example on the front of the body. The other way we reference structures in the body is by describing their position relative to something else. For example, we might refer to a muscle as being above, below, underneath, or on top of another muscle. Keep that in mind as we walk through common anatomical terms for position and how we often use them. Additionally, sometimes there is more than one set of anatomical terms to describe particular positions and locations. Where there is more than one set of terms for a position in the body, we’ll discuss both. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Anatomical terms for position and location ### Superior and inferior The first set of terms we’ll discuss are anatomical terms for structures that are above or below another structure. We have two sets of terms we can use to describe parts of the body that are above or below something else. The term superior refers to something that is above something else. Inferior means that something is below something else. ### Cranial and caudal We have a second set of anatomical terms that aren’t used quite as often but have a similar meaning to superior and inferior. We can also use the terms cranial and caudal to describe the relative position of structures that are above or below something in the body. Something that is cranial means it is toward the head compared to another structure. Something that is caudal means it is towards your “tail,” or away from your head, which in the case of a human in anatomical position would be closer to your feet. Because we are describing the location of structures from [anatomical position](https://3dmusclelab.com/anatomical-position/), something that is above something else would also be closer to the head. A structure that is below another structure would also be closer to the feet. If we know the roots of these anatomical words, the meanings of the roots of these words can help us potentially understand and remember the anatomical terms. Cranial is related to the word cranium which you probably already know refers to the skull. So it makes sense that something that is in the cranial direction is something closer to the skull or head. Caudal is related to the word cauda which means tail. So, likewise, it makes sense that something that is in the caudal direction is closer to the tail. ### Lateral and medial The next set of anatomical terms we’ll look at involve describing the position of structures in relation to the midline of the body. If we draw a line from the top of our head to our feet that bisects the body into a right and left side in the [sagittal plane](https://3dmusclelab.com/planes-of-movement/), that is referred to as the midline of the body. Something that is closer to that midline positionally is referred to as more medial. Something farther from that midline or closer to the outside of the body is referred to as more lateral. ### Internal and external The terms internal and external are similar to the terms lateral and medial. The terms internal and external are used interchangeably with lateral and medial when we are describing a direction of movement. Movement such as rotation in the medial direction, describes movement that is going internally, or closer to the midline (inside) of the body. Movement in a lateral direction is movement externally, away from the center of the body, or towards the outside of the body. However, when we refer to a position of a structure, rather than a movement, we typically use the words lateral and medial. ### Anterior, posterior, ventral, and dorsal If we divide our body into a front and back half in the coronal plane, this is where we apply the anatomical terms anterior and posterior. A structure that is more anterior is closer to the front of the body. Something that is more posterior is closer to the back of the body. Additionally, there is another set of terms that are used similarly to anterior and posterior, but are used less often. Those terms are ventral and dorsal. Ventral, like the term anterior, is used to refer to a structure that is on the front of the body. Dorsal is similar to posterior and refers to a structure that is on the back of the body. ### Distal and proximal The next two terms, distal and proximal, are primarily used to describe only the relative position of structures on the appendicular skeleton in relation to their distance from the axial skeleton. Remember that the appendicular skeleton includes arms, legs, [shoulder girdle](https://3dmusclelab.com/shoulder-girdle/), and [pelvic girdle](https://3dmusclelab.com/exploring-the-pelvis/). The rest of your skeleton, including the [spine](https://3dmusclelab.com/exploring-the-spine/), ribcage, head, and [neck](https://3dmusclelab.com/neck-muscles-superficial/), is considered the axial skeleton. Distal is used to describe a structure on the appendicular skeleton that is farther away from the axial skeleton than something else (on the appendicular skeletal system). The term proximal is used to describe a structure that is closer to the axial skeleton than something else (on the appendicular skeletal system). For example, we could say that our fingers are distal to our elbow because they are farther away from the rest of our body (our axial skeleton) than our elbow. ### Ipsilateral and contralateral Ipsilateral and contralateral are two frequently confused words for the position of body structures. If we break down the roots of these two words it can help us understand their meaning. The prefix “ipsi” means the same. The prefix “contra” means opposite or against. Lateral means the side of something. So these are anatomical terms that describe whether something is located on, or happening on, the same side or opposite side as something else. These words can be used to describe relative position in the body or relative [movement](https://3dmusclelab.com/functional-movement/). For example, I could say my internal oblique muscles run from my iliac crest and inguinal ligament to my ipsilateral lower ribs because the [internal oblique muscle](https://3dmusclelab.com/abdominal-muscles/) travels between these attachments on the same side of the body. If I’m using these words to describe movement, I could say that when we walk, as we step with the right foot, our contralateral arm swings forward at the same time. We would use the word contralateral to describe that [movement in gait](https://3dmusclelab.com/what-is-the-gait-cycle/) because it is our opposite arm that swings forward when we take a step. ### Superficial and deep The anatomical terms superficial and deep describe the depth at which something is found in the body. Another way to say that is that these terms describe how close to the surface of the body something is relative to something else. Superficial refers to a structure that is closer to the surface of the body. Deep refers to a structure that is farther away from the body’s surface. For example, I could say my skin is superficial to my biceps brachii muscle. Or, I could compare the depth of two [muscles](https://3dmusclelab.com/what-is-a-muscle/). For example, the [brachialis muscle](https://www.yoganatomy.com/the-brachialis-muscle/) is deep to (underneath) the [biceps brachii muscle](https://3dmusclelab.com/elbow-and-forearm-in-movement/). ### Supine and prone The terms supine and prone are a little different from the terms I’ve explained so far. These two terms describe the position of the whole body in space. Supine is the anatomical term to describe lying face up. Prone is the anatomical term to describe lying face down. ## Conclusion The body is complex. An important part of learning about the body including the study of [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) is being able to communicate clearly what we see. Anatomical terms help us do that. Anatomical terms for position help us use precise language to describe where structures are located in the body and how they are positioned in relation to the front, back, top, bottom, inside, and outside of the body, as well as how they are positioned in relation to other structures. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/planes-of-movement/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Understanding The Planes Of Movement ![The Planes Of Movement](https://3dmusclelab.com/wp-content/uploads/2023/10/planes-of-movement.jpg) Human anatomy and kinesiology have a language just like any other area of study. Having terms to refer to bones, muscles, directions, and types of movement helps us be specific. It also helps us clearly communicate with other people about the body. That is especially true when talking about planes of movement because understanding simple aspects of movement makes it possible for us to better understand more [complex movement](https://3dmusclelab.com/functional-movement/). ## Why do we need planes of movement? The planes of movement help us describe actions that happen from [anatomical position](https://3dmusclelab.com/anatomical-position/). Remember that in anatomical position, we are standing upright with our arms by our sides, with our palms facing forward. Realistically, we don’t begin or end most activities from anatomical position. But even though it might be overly simplistic for describing real-life movement, it helps us establish our basic understanding of the directions of movement before diving into more complexity. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the planes of movement? There are three main planes of movement. They are described from anatomical position in a way that is similar to an x/y/z coordinate system on a graph. These are hypothetical, or imaginary lines in the body. They are not actual lines that you can see of course. ### Sagittal plane If you picture the body in anatomical position and then place a vertical line through the body which divides it into a right and left side, you are describing the sagittal plane. Movements of flexion and extension happen in this plane. For instance, sit-ups happen in the sagittal plane. In the sagittal plane, we have an additional term that refers more specifically to bisecting the body exactly through the midline. That’s referred to as the midsagittal plane. ### Frontal or coronal plane If you draw a vertical line through the body in anatomical position that divides the body into a front and back, then you are describing the frontal plane. That plane is also called the coronal plane. The movements that happen in that plane are abduction and adduction. Jumping jacks, for example, are a great example of a movement that happens in the frontal plane. ### Transverse or horizontal plane Finally, if you draw a horizontal line through the body that divides the body into a top and bottom section then you are describing the horizontal plane. That plane is also called the transverse plane. Rotational movements happen in that plane. Turning your head to look over your shoulder and [rotation of the spine](https://3dmusclelab.com/exploring-the-spine/) are examples of movements that happen in the transverse plane. ## Planes of movement in real life In real-life movement, we commonly move in more than one plane at once. If you pick just about any familiar movement, you can imagine this. For example, if you picture reaching above your head to get an item out of a cabinet, you are likely reaching at an oblique angle. So, rather than purely doing flexion and extension in the sagittal plane, you are actually doing some combination of flexion/extension and abduction/adduction. Those kinds of combinations better reflect real-life movements. This is sometimes referred to as moving in diagonal or oblique planes of movement. In order for movement to happen in the diagonal plane, the joint, or [joints](https://3dmusclelab.com/synovial-joint/), that are moving must be able to move in at least two of the planes already described. In addition to the example already given, a baseball pitch, a golf swing, kicking a football, and some [yoga postures](https://www.yoganatomy.com/bind-marichyasana-c-and-bound-twists/), all happen in the diagonal plane. However, if we experience pain, injury, weakness, tightness, or other sensations in our body, it can be helpful to break more complex actions down into simpler individual planes of movement. That has the potential to tell us something about how we might address what we’re experiencing if it is something we want to change. In even more complex and dynamic movements like [walking](https://3dmusclelab.com/what-is-the-gait-cycle/), we aren’t just moving a single joint through more than one plane at a time. We’re moving many joints through multiple planes simultaneously. So you can imagine it might be overwhelming to try to diagnose an issue with dysfunction or design a strength-training plan for everything all at once. This is where it can be helpful to break things down into parts. ## Conclusion There are three main planes of movement, the sagittal, frontal or coronal, and horizontal or transverse planes. These planes are hypothetical lines through the body, not physical lines that we can see. However, the concepts of these simple planes can be helpful for understanding more complex, multiplanar movements. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/valgus-and-varus-knee-pain/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Valgus And Varus Knee Patterns And Knee Pain ![Valgus And Varus Knee Patterns](https://3dmusclelab.com/wp-content/uploads/2023/01/valgus-vargus.jpg) Knee pain is complex, varied, and has many sources. Causes range from acute trauma, like broken bones, to chronic aches and pains with no obvious source. One potential contribution to knee pain can simply be our postural patterns. In this article, let’s take a closer look at a particular knee-related aspect of our posture that can sometimes lead to knee pain: valgus and varus knees. ## What are valgus and varus patterns? A valgus knee pattern is what is colloquially sometimes called “knock-knees.” In this case, the angle between the tibia and the femur on the lateral side is smaller than it should be ideally and that angle is wider on the medial side than the ideal. In contrast, a varus knee pattern, colloquially called “bow legs,” is the opposite. The angle between the tibia and the femur is reduced on the medial side and greater on the lateral side than what is considered neutral. To simplify the naming of these patterns, Tom Myers of Anatomy Trains and others refer to the valgus knee pattern as an X-leg pattern and the varus knee structure as an O-leg pattern. Either of these patterns might be mild, with small variations in angle size in relation to what is considered neutral. In that case, the person might not experience any reduced function or pain. At the other end of the spectrum, these patterns can show up in more extreme variations. More extreme versions of these patterns can negatively affect function and sometimes cause pain. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What drives these knee patterns? The source of these patterns is complex. It may be congenital, the result of disease complications, the result of acute trauma like a broken bone, or other reasons. And, these postural patterns don’t exist in isolation, of course. They’re in the middle of the whole lower kinetic chain between the pelvis and the feet and ankles. For that reason, tension above or below can influence knee position. And, the reverse is also true. These patterns affect the way tension is held at joints above and below the knee. So both acute trauma, as well as patterns from chronic use acquired elsewhere in the body, can contribute to valgus or varus knee position. ## Do you have a valgus or varus knee position? Let’s do a little experiment to learn about your own posture. Stand in front of a mirror where you can see your knees. Slowly scoot your feet together. Notice which touches first, your feet or the insides of your knees. When you bring your feet together, do the insides of your knees meet first? Then, you have a valgus, or X-leg pattern. Do your feet meet first and do you also have significant space between your knees when your feet are together? Then you have a varus, or O-leg pattern. If your feet and the insides of your knees meet at about the same time, then your knee pattern is neutral with respect to an X-leg or O-leg pattern. ## How are these patterns related to knee pain? [The knee](https://3dmusclelab.com/knee-joint/) is primarily a hinge joint. That is, it flexes and extends easily in the frontal plane. On both the medial and lateral sides of the knee are [ligaments](https://3dmusclelab.com/ligaments-and-tendons/) holding the knee in place and resisting any pressure too far in either direction. On the medial side is the medial collateral ligament. And, on the lateral side is the lateral collateral ligament. You could imagine then that if we chronically put pressure on either of these ligaments with a valgus or varus-positioned knee that those ligaments could get over-stretched and then irritated and sore after a while. Additionally, we have both a medial and lateral meniscus. Remember our menisci are semi-circular discs that help cushion the knee. They allow the femur and tibia to glide past each other during movement. If we’re chronically putting more tension on either the lateral or medial side of [our knee joint](https://3dmusclelab.com/knee-hyperextension/), then we can potentially pinch the meniscus on the side where the tibia and femur are closer together. That can also irritate the tissues in that area and cause soreness. In both the X-leg and O-leg positions, the load-bearing force is not going through the center of the knee. Instead, the line of force is more off to one side or the other. That affects where tension goes. Over time it can increase the chances of osteoarthritis due to the extra stress either on the inside or outside of the knee and potentially result in pain (Miura et al., 2009). In an X-leg position specifically, the pattern has been linked to an increased likelihood of patellofemoral pain (Gwynne and Curran, 2018; Herrington, 2014). ## Can we change knee patterns? Yes, it is possible to change these patterns, to a point. But, if we really want to change them, we have to look more holistically at the body. There may be a genetic component to the angle of the joints at the [hip](https://3dmusclelab.com/exploring-the-adductor-muscles/), knee, and ankle. Those aren’t likely to change. Our knee position may also result from something we can’t change like a disease or acute injury. But we also acquire our patterns from activities we do as well as accidents and injuries we’ve experienced. If those patterns are held in the [soft tissue](https://3dmusclelab.com/what-is-connective-tissue/) ([muscles](https://3dmusclelab.com/what-is-a-muscle/) and [fascia](https://3dmusclelab.com/what-is-muscle-fascia/)), then there is some potential to change them. We would need to consult with an appropriate medical professional like a physical therapist or experienced bodyworker for a full assessment to understand the range within which change might be possible for our pattern. ## Conclusion Valgus and varus knee positions describe the way the tibia meets the femur at the knee joint. They refer to a pattern where the knee is positioned either medial or lateral of the ideal. In this position, the knee is more vulnerable to some types of strain on tissues surrounding it, which may cause pain as well as reduced function. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Gwynne, C.R. and S.A. Curran. 2018. Two-dimensional frontal plane projection angle can identify subgroups of patellofemoral pain patients who demonstrate dynamic knee valgus. Clinical Biomechanics. 58:44-48.](https://pubmed.ncbi.nlm.nih.gov/30015205/) [Herrington, L. 2014. Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls. The Knee. 21:514-517.](https://pubmed.ncbi.nlm.nih.gov/24380805/) [Miura, H., S. Takasugi, T. Kawano, T. Manabe, Y. Iwamoto. 2009. Varus-valgus laxity correlates with pain in osteoarthritis of the knee. The Knee. 16:30-32.](https://pubmed.ncbi.nlm.nih.gov/18954990/) --- Source: https://3dmusclelab.com/ligaments-and-tendons/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Are Ligaments And Tendons The Same Thing? ![ligaments tendons](https://3dmusclelab.com/wp-content/uploads/2019/01/ligaments-tensons.jpg) Ligaments and tendons are both important structures in the body. Although they are sometimes confused with one another, they are two different kinds of structures. In this article we’ll help you distinguish ligaments from tendons and we’ll look at what both of these important structures do. ## What ligaments and tendons have in common Ligaments and tendons are both types of [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Both structures are composed of a greater proportion of collagen fibers than elastin fibers and both have their fibers packed in densely. This composition gives ligaments and tendons a very strong tensile strength. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are ligaments? Ligaments connect bone to bone. They function to stabilize and restrict the amount of movement in specific directions at a joint. Some examples of ligaments that you may have heard of are the medial collateral ligament (often abbreviated MCL) and the lateral collateral ligament of the knee (often abbreviated LCL). The medial collateral ligament prevents the bones of the knee joint from moving too much in a medial direction. The lateral collateral ligament prevents the bones of the knee joint from moving too much in the lateral direction. ## What are tendons? Tendons connect muscle to bone. They function with muscles to create movement by moving a bone at a joint. An example of a tendon that you have probably heard of is the Achilles tendon at the ankle. The gastrocnemius and soleus muscles of the calf come together at the back of the ankle and become the strong Achilles tendon that then attaches to the calcaneus, or heel bone. When the gastrocnemius and/or soleus muscle contracts to plantarflex the foot, that action includes the involvement of the Achilles tendon. ## Ligaments and tendons are connective tissue Just like a [muscle](https://3dmusclelab.com/what-is-a-muscle/), both ligaments and tendons have layers of fascia wrapping each layer of their structure. These fascial layers are continuous with the structures that they are attached to, either bone or muscle. Ligaments and tendons are so well integrated through fascia with the structures that they attach to that if you went into the body, you would not be able to draw a line showing where muscle or bone ended and ligament or tendon began. This integration helps make both ligaments and tendons very effective at their particular functions. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # How Do You Determine Muscle Agonists, Antagonists, And Synergists? ![Agonist, Antagonist, and Synergist](https://3dmusclelab.com/wp-content/uploads/2019/05/arm-flexing-agonist.jpg) *In this example, biceps brachii is the agonist or prime mover. Triceps brachii is the antagonist and brachialis is a synergist with biceps brachii.* ![Muscle Agonist, Antagonist, and Synergist](https://3dmusclelab.com/wp-content/uploads/2019/05/arm-flexing-agonist.jpg) In this example, biceps brachii is the agonist or prime mover. Triceps brachii is the antagonist and brachialis is a synergist with biceps brachii. As we begin to study muscles and their actions, it’s important that we don’t forget that our body functions as a whole organism. Although we learn the actions of individual muscles, in real movement, no muscle works alone. While we often have one main muscle to do an action, it is nearly always assisted in that action by other muscles. To keep things in balance in the body we also nearly always have a muscle that is assisting, resisting, or opposing any action. Let’s take a look at how we describe these relationships between muscles. ## Muscle agonists We describe the main muscle that does an action as the agonist. It is sometimes also called the “prime mover”. Many actions in the body do have one muscle that is responsible for more of the work in that action than any other muscle. For example, the agonist, or prime mover, for hip flexion would be the [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/). Although it does not work alone, iliopsoas does more of the work in hip flexion than the other muscles that assist in that action. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle antagonists In order to maintain a balance of tension at a joint we also have a muscle or muscles that resist a movement. The main muscle that resists a movement is called the antagonist. We could also say that the antagonist is the main muscle that does the opposite of the action that it is resisting. For example, we could say that gluteus maximus is an antagonist of the primary hip flexor, [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) because gluteus maximus is a hip extensor. Gluteus maximus is an antagonist of iliopsoas, which does hip flexion, because gluteus maximus, which does extension of the hip, resists or opposes hip flexion. ## Muscle synergists We describe muscles that work together to create a movement as synergists. For example, iliacus, psoas major, and rectus femoris all can act to flex the hip joint. There are some sections within other muscles that can also assist with flexion of the hip joint, for example, the anterior fibers of gluteus minimus and gluteus medius can assist with flexion of the hip joint, depending on the position of the hip when it’s being flexed. All of these muscles together could be referred to as synergists for flexion of the hip joint. In real life, outside of [anatomical position](https://3dmusclelab.com/anatomical-position/), we move our body in all kinds of creative and interesting ways. While we need the main muscle, or agonist, that does an action, our body has a good support system for each action by using muscle synergists. Likewise, our body has a system for maintaining the right amount of tension at a joint by balancing the work of a muscle agonist with its antagonist. Balance between a muscle agonist, its synergists, and its antagonist(s) is important for healthy movement and avoiding pain and injury. Want to learn more about terminology and the language of kinesiology? Check out our articles: [What Is Anatomical Position?](https://3dmusclelab.com/anatomical-position/) and [What Is Muscle Origin, Insertion, and Action?](https://3dmusclelab.com/origin-insertion-and-action/) The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscle-strengthening/ Author: David Keil · Updated: 2026-06-20 Anatomical Applications # What Do We Mean By Muscle Strengthening? ![Muscle Strengthening](https://3dmusclelab.com/wp-content/uploads/2026/06/muscle-strengthening.jpg) Muscle strengthening is a big topic in the media these days, and it’s not just for bodybuilders anymore. The importance of building and maintaining muscle strength has been emphasized for athletes, [older folks](https://3dmusclelab.com/muscles-when-we-age/), people recovering from [injuries](https://3dmusclelab.com/ankle-sprain/), women, and many other populations. But what do we mean when we say [muscle](https://3dmusclelab.com/what-is-a-muscle/) strengthening? In this article, we’ll take a look at what muscle strengthening is, what happens when we strengthen muscle tissue, and what some of the benefits are. ## What is muscle contraction? Depending on our particular context, when we say muscle strengthening, we probably think of lifting weights at the gym. Lifting weights is one type of strength training. But it’s not the only kind of muscle strength, because shortening to contract is not the only type of muscle action. Let’s start with the basics and briefly review skeletal [muscle contractions](https://3dmusclelab.com/muscle-contractions/). Remember that muscles don’t just contract and shorten. Muscles can act in several different ways. When a muscle shortens when we contract it, that’s called a concentric contraction. A muscle can also lengthen during a contraction. That’s called an eccentric contraction. Finally, we can contract a muscle in situations where it doesn’t change length at all. That’s called an isometric contraction. If we’re thinking about muscle strength, concentric muscle contractions are what happen when we lift a dumbbell at the gym to do a [bicep](https://3dmusclelab.com/biceps-and-triceps/) curl. Isometric contractions are what your biceps muscles are doing when you hold the dumbbell without moving it anywhere along the way. Eccentric contractions are what your biceps muscles are doing when you slowly lower the dumbbell back down. Each of those situations calls for a different kind of muscle strength. Additionally, there are other, more specific situations where we rely on muscle strength, like the dynamic muscle strength that we need to run up a steep hill, for example. Regardless of the type of contraction, when our [muscles are acting](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/), muscle cells are firing and using up ATP, or energy, at a cellular level, to do work. At a cellular level, when we challenge skeletal muscle tissue by using it, we have a fair idea of what happens. When our nervous system cues a muscle cell to activate through the release of calcium, the individual muscle cell proteins, actin and myosin, are attracted to each other like two magnets. The amount of muscle force is the total of each of the muscle cells that are activating at the same time to do a muscle contraction. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is muscle strengthening? Perhaps surprisingly, however, when we zoom out to a more macro level, our understanding of what happens when we feel stronger or show measurable gains on one or more strength tests is more murky. As with an [increase in flexibility](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/), an increase in strength comes from more than one type of change in our body. Those changes are both in the tissue itself and in our nervous system. Science doesn’t have a complete explanation of exactly what happens physiologically when we have the felt sense that we feel stronger. ### Hypertrophy and muscle strength When we strengthen [muscles](https://3dmusclelab.com/what-is-muscle-fascia/), at least some of the time, hypertrophy occurs. Hypertrophy is the name for an increase in muscle cell size. Increasing tension on our muscles is often correlated with an increase in the size of muscle cells. Interestingly, we can also increase muscle size without increasing strength. The increases we experience in muscle mass are not always correlated with increases in muscle strength. Muscles can increase in size for different reasons. The number of microfibrils can increase, or the fluid volume inside the muscle can increase. An increase in the number of microfibrils is associated with increased strength, but an increase in fluid volume alone is not. ### The nervous system and muscle strength Additionally, when we increase muscle strength in a way that we see an increase in measurements of strength, changes in our nervous system that affect nerve to muscle communication also happen. A recent review paper from 2018 (Suchomel et al., 2018) specifically reported aspects of nerve to muscle communication, including “motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition.” While these actions are more technical than we can cover here, what’s important to understand is that our nervous system also has a role to play in muscle strengthening. ## Applying muscle strength research Although every aspect of muscle strengthening physiology might not be worked out by researchers yet, we do know that the type of resistance training you might already do at the gym or in a fitness class focused on strength-building is effective at building muscle strength. Many research studies agreed, as you might expect, that greater load and frequency led to greater increases in muscle strength. ## Why strengthen our muscles? Although we may not yet have a complete explanation of what happens physiologically when we strengthen our muscles, it’s clear that there are benefits associated with measurable gains in many types of strength. Research found that increased muscle strength was correlated with many aspects of health and wellness, from reductions in diabetes symptoms, decreased obesity, increased longevity, and improved fibromyalgia symptoms, to decreased chances of a cancer diagnosis. All of those are great reasons to keep up with our favorite activities for maintaining muscle strength. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bennie, J.A., D. Lee, A. Khan, G.H. Wiesner, A.E. Bauman, E. Stamatakis, and S.J.H. Biddle. 2018. Muscle-Strengthening exercise among 397,423 U.S. adults: Prevalence, correlates, and associations with health conditions. American Journal of Preventive Medicine. 55 (6): 864-874.](https://www.sciencedirect.com/science/article/abs/pii/S0749379718321378) [Effects of muscle strengthening versus aerobic exercise program in fibromyalgia. 2008. Bircan, C., S.A. Karasel, B. Akgün, O. El, S. Alper. Rheumatol Int 28:527–532.](https://pubmed.ncbi.nlm.nih.gov/17982749/) [Enoka, 1988. Muscle strength and its development: New perspectives. Sports Medicine 6:146-168.](https://pubmed.ncbi.nlm.nih.gov/3055145/) [Foster C. and M.E.G. Armstrong. 2018. What types of physical activities are effective in developing muscle and bone strength and balance? J Frailty Sarcopenia Falls. 3(2):58-65.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7155324/) [Andrews, M. A.W. 2003. Oct. 27. How does exercise make your muscles stronger? Scientific American. Online. Accessed June 10, 2026.](https://www.scientificamerican.com/article/how-does-exercise-make-yo/) [Lopez P., R. Radaelli, D.R. Taaffe, R.U. Newton, D.A. Galvão, G.S. Trajano, J.L. Teodoro, W.J. Kraemer, K. Häkkinen, and R.S. Pinto. 2021. Resistance training load effects on muscle hypertrophy and strength gain: Systematic review and network meta-analysis. Med Sci Sports Exerc. 53(6):1206-1216.](https://pubmed.ncbi.nlm.nih.gov/33433148/) [Mcleod J.C., B.S. Currier, C.V. Lowisz, and S.M. Phillips. 2024. The influence of resistance exercise training prescription variables on skeletal muscle mass, strength, and physical function in healthy adults: An umbrella review. Journal of Sport and Health Science. 13(1): 47-60.](https://pubmed.ncbi.nlm.nih.gov/37385345/) [Reggiani C. and S. Schiaffino. 2020. Muscle hypertrophy and muscle strength: dependent or independent variables? A provocative review. Eur J Transl Myol. 30(3):9311.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7582410/) [Suchomel, T.J., S. Nimphius, and C.R. Bellon, et al. 2018. The importance of muscular strength: Training considerations. Sports Med 48:765–785.](https://link.springer.com/article/10.1007/s40279-018-0862-z) --- Source: https://3dmusclelab.com/bones-when-we-age/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Happens To Bones When We Age? ![Bones and Aging](https://3dmusclelab.com/wp-content/uploads/2025/08/aging-bone-structure.jpg) Aging happens to everyone, but how we age is, to some degree, something we can influence. Our body is always in flux, changing in one way or another. During some periods of growth, like puberty, that span of change is fairly rapid and dramatic. The process of what and how things change throughout our body in our later years can be more gradual, depending on the individual and their context. But whether we experience more abrupt changes or slow shifts over time, every system in our body changes as we get older. In this article, part two in our series on tissues and aging, we’ll look specifically at how aging affects our bones. ## What’s a bone? Remember that bone is a living tissue. It’s not a dry, desiccated, or unchangeable substance. It’s actually a type of [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Bone has a particular extracellular organic matrix, which its components, cells, lipids, and inorganic minerals, exist within. That matrix is collagen, as well as some additional proteins. Within that matrix, we find bone cells. Bone cells include osteoblasts, osteocytes, and osteoclasts. Osteoblasts synthesize bone. Osteocytes help regulate the mineral concentration in bone. Osteoclasts participate in the process of breaking down bone, called bone resorption. Our bones have multiple functions. They have the obvious structural and mechanical function of providing support for our structure. The particular way that bones come together at a [joint](https://3dmusclelab.com/synovial-joint/) allows for movement and helps distribute load and force. Bones also serve as a production site for blood cell production and a reservoir for certain minerals. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## How do bones develop? Our bones begin to form in the embryo, initially as cartilage. The cells present in that tissue differentiate into bone cells, and eventually, that cartilaginous tissue ossifies into what we recognize as bone. Our bones continue growing and changing in character as we move through stages of childhood and early adolescence. Our long bones, like our femur, tibia, and humerus, for example, stop getting longer around puberty. However, our bones continue a different growth process, called appositional growth, well into our adulthood. That process allows them to get wider and change shape as a response to mechanical loading. ## How do bones change as we age? There are many normal changes that happen to our bones as we move into our middle and later years. One of the biggest changes is that our overall bone mass commonly begins to decline as we move from early adulthood into our middle years. This happens because the balance between new bone creation by osteoblasts and the breaking down of bone by osteoclasts shifts in favor of more resorption compared to new bone creation. In addition to the loss of bone mass, we typically experience an increase in bone marrow fat. Exactly why this shift in favor of more resorption and less bone creation happens is uncertain. There appear to be some unavoidable age-related reasons for this change. But, some amount of bone loss may also be correlated with a decrease in [physical activity](https://3dmusclelab.com/functional-movement/) that is common in middle age through our older years. ### Bone mass decline The loss of bone mass potentially starts earlier than you might expect. Peak bone mass typically occurs between ages 15 and 30, depending on individual factors, especially gender. Women typically develop peak bone mass earlier, between ages 15 and 20. Men typically reach peak bone mass later. Declining bone mass commonly starts somewhere around age 40, if not before. Men generally have a higher peak bone mass than women. Women typically experience an accelerated decline in bone mass at menopause due to the somewhat abrupt decline in estrogen. ### Other changes In addition to the change in the balance of bone formation with breaking down, there are other distinct age-related changes in bone that occur in both men and women. Changes in protein content, mineral content, and bone architecture, as well as an increase in microfractures, usually occur. Decreased calcium and vitamin D availability due to the overlapping effects of nutrition and age-related hormonal changes reduces the availability of those minerals. That can accelerate bone loss by decreasing bone formation. The cumulative effect of these age-related changes is that bones become more fragile in our later years. ## Why do age-related changes to bone matter? Age-related changes to our skeletal system and bones can have wide-ranging effects. These changes, perhaps surprisingly, can affect other body systems because they are intricately interwoven. Recent research shows an interesting two-way relationship between bone growth and maintenance and immune cell development and maintenance. Changes in bone mass can therefore affect our immune system, and vice versa. Similarly, our vascular system is interrelated with our skeletal system. Age-related decline in our vascular health can affect our bone health. ### Osteoporosis and fractures More specifically related to our skeletal system, a decrease in bone mass in our later years can lead to osteoporosis. This is the term used to describe a particularly significant decrease in bone mass, usually age-related, along with structural changes to our bones, which make them more fragile. The loss of bone mass, generally, and osteoporosis specifically, can increase the risk of [bone fractures](https://3dmusclelab.com/bone-breaks-fractures-and-heals/) during a fall as well as increase the risk of [spinal](https://3dmusclelab.com/exploring-the-spine/) [deformities](https://3dmusclelab.com/muscles-affected-in-scoliosis/) and other bony dysfunction. As you might remember from my last article on [aging and muscles](https://3dmusclelab.com/muscles-when-we-age/), our balance and proprioception tend to decline as we age, making falls more likely. The increasing fragility of our bones makes the potential consequences of those falls more serious. ## What can you do to slow bone decline? Age-related changes in bone are not consistent across the population. Some people experience more dramatic bone-related changes than others, and some people experience them much sooner than others. There are multiple factors that affect the individual trajectory of this change. Some part of what we experience is influenced by our genetics. However, healthy lifestyle choices also significantly affect how we experience aging. Healthy lifestyle choices to maximize our peak bone mass delay the effects of age-related bone mass decline. Those healthy lifestyle choices that increase our likelihood of maximizing peak bone mass include things like maintaining optimal exercise routines. That means incorporating weight-bearing exercise in multiple planes by doing strength-training as well as activities like [Pilates](https://3dmusclelab.com/teaching-pilates-aids-musculoskeletal/) or [yoga](https://www.yoganatomy.com/yoga-balance-bone-health/). A healthy lifestyle for maximizing bone mass also includes not smoking, maintaining optimal nutrition, including sufficient calcium and vitamin D, and avoiding excessive alcohol. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Boskey, A. L. and R. Coleman. 2010. Aging and bone. J Dent Res. 89(12):1333-48.](https://pmc.ncbi.nlm.nih.gov/articles/PMC2991386/) [Demontiero, O., C. Vidal, and G. Duque. 2012. Aging and bone loss: new insights for the clinician. Ther Adv Musculoskelet Dis. 4(2):61-76.](https://pmc.ncbi.nlm.nih.gov/articles/PMC3383520/) [Kiebzak, G.M. 1991. Age-related bone changes. Experimental Gerontology. 26(2–3): 171-187.](https://www.sciencedirect.com/science/article/abs/pii/053155659190010J) [Mi, B., Y. Xiong., S. Knoedler. et al. 2024. Ageing-related bone and immunity changes: insights into the complex interplay between the skeleton and the immune system. Bone Research. 12:42.](https://www.nature.com/articles/s41413-024-00346-4#) --- Source: https://3dmusclelab.com/what-is-a-muscle/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Do You Know What A Muscle Is? ![muscle anatomy](//3dmusclelab.com/wp-content/uploads/2018/05/what-is-muscle.jpg) You probably know that you use your muscles to do just about any and every action in your body from routine actions like walking to specialized [movements like yoga](https://www.yoganatomy.com/muscle-activation-in-yoga-transitions/). But, do you really know what a muscle is? Muscles are more intricate than we often realize. While we might think of them as one solid thing, they are actually far more nuanced than that. Muscles are actually composed of a multi-layered structure. And, it’s their structure is that makes them so functional. Would it surprise you if I said that they are mostly [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/)? ## Types We actually have three different types of muscle tissue. We have cardiac muscle which is found only in the heart. There is also smooth muscle tissue. This kind of tissue is found in our organ walls. It’s involved in many of the involuntary actions that our organs do. And third, we have skeletal muscle. This is the type of muscle tissue you’re probably most familiar with. Examples include many that you’ve heard of like the hamstrings, the biceps, the triceps, and the quadriceps. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Skeletal muscle structure Let’s break this down and take a deeper dive into structure. Picture a whole skeletal muscle that you’re familiar with. Let’s say the biceps brachii in the arm. This “whole muscle” is really a group of what are called muscle fascicles wrapped in a layer of [fascia](https://3dmusclelab.com/what-is-muscle-fascia/) called the epimysium. You could picture a skeletal muscle a bit like a grapefruit. The grapefruit peel is like the fascia that wraps around the fascicles. The fascicles are like the pulpy sections of the grapefruit. We can go even deeper into layers of skeletal muscle structure, however. Each fascicle is composed of a bundle of fibers and each of those bundles is wrapped in a layer of fascia which is called the endomysium. We could compare this to an individual wedge or section of a grapefruit where a bunch of pieces of pulp are held together by a wrapping of tissue. Each of these fibers is itself a group of cells that is wrapped in fascia. At the smallest level, a muscle cell is made up of two proteins: actin and myosin. ## Muscle function What makes a muscle work or “contract” then? Contraction happens at the level of individual cells. The two types of proteins, actin and myosin, are arranged in a row. When the nervous system sends a signal that a contraction is needed, calcium is released and this triggers the two proteins to be attracted, or pulled toward one another. At a cellular level, this is what happens when a muscle contracts. ## Integration Holding this idea in our mind of skeletal muscles as multi-layered, rather than a solid thing, can help us understand how skeletal muscles and muscle tissue are not separate from the rest of the body. A single muscle is inseparable from the fascia that is interwoven within its layers. A single skeletal muscle, because of its connecting fascia, is also inseparable from the “individual” muscles that surround it. We should keep this in mind as we deepen our understanding of skeletal muscles and movement. While we may talk about “individual” muscles for the purposes of breaking down our understanding of the body into manageable chunks, movement happens with the whole body and is affected by the whole body. ## Conclusion Skeletal muscles are many-layered tissues intimately connected to each other and to other structures in our body. This interconnection is what makes fluid whole-body movement possible. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/synovial-joint/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Parts Make Up A Synovial Joint? ![Synovial Joint](https://3dmusclelab.com/wp-content/uploads/2019/11/synovial-joint.jpg) A joint is where two bones come together. We have different types of joints in the body. One important way that joints are classified is based on the amount of movement that is possible at that joint. The amount of movement is different depending on how the joint is connected. We have three main types of joints based on the amount of movement that is possible: - Synarthrotic joints - Amphiarthrotic joints - Diarthrotic joints ## Synarthrotic joints Synarthrotic joints are joints where little to no movement happens. These joints are connected with a fibrous connection that doesn’t allow for essentially any movement. One of the best examples of these type of joints are the sutures between the bones in our skull. It would be problematic if there were lots of movement happening between the bones of the skull! ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Amphiarthrotic joints Amphiarthrotic joints are joints where very small amounts of movement can happen. These joints are joined with a cartilaginous connection that allows for some small amounts of movement. One example of an amphiarthrotic joint is the pubic symphysis, the joint that connects the two sides of the pelvis on the anterior side. Another example is the joint created by the disc between each vertebra in the spine. ## Diarthrotic joints or synovial joints Finally, we have diarthrotic joints. These are the joints we’re often most familiar with where most movement happens in the body. There are lots of examples of diarthrotic joints including: the glenohumeral joint (the shoulder), the femorotibial joint (the knee), and the acetabulofemoral joint (the hip). These joints have a special construction that allows for lots of movement to happen there. The end of each bone that comes together at a synovial joint has a layer of smooth cartilage called articular or hyaline cartilage. A structure called a joint capsule encapsulates the area where the two bones come together to make a joint. The joint capsule is lined with a membrane, called the synovial membrane, that produces a fluid, called synovial fluid, which lubricates the joint where the two bones meet. This structure allows for the movement that we are familiar with at our joints. As the presence of synovial fluid is unique to diarthrotic joints, they are also sometimes called synovial joints. If you want to learn more about structures that enable movement in the body, check our articles on [muscle fascia](https://3dmusclelab.com/what-is-muscle-fascia/), [connective tissue](https://3dmusclelab.com/scar-tissue/), and [ligaments and tendons](https://3dmusclelab.com/ligaments-and-tendons/). #### Related Posts The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/anatomical-position/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # When Do We Use Anatomical Position? ![Anatomical Position](https://3dmusclelab.com/wp-content/uploads/2019/02/anatomical-position.jpg) If we are going to communicate clearly about something, in this case kinesiology, then it’s important that we agree on a language to use. As you’ve no doubt already begun to realize, movement can be complicated! This is where having a language that means something specific is important. In anatomy and [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) we use directional terms and terms that describe the most basic movements to help us describe where things are in relationship to one another. ‘Anatomical position’ is another term that helps us be specific about what we’re describing. ## What does anatomical position look like? There are really two anatomical positions. There is one position considered western and another considered eastern. They are more similar than different, but they do have some slight differences. In the western position, we are looking at a person standing who is facing forward, with their legs slightly apart, with arms by their sides, and their palms facing forward. In the eastern position the feet may be positioned together and the hands may be held above the head rather than by the sides of the body. Most of the time, if you see or hear a reference to anatomical position, it means the western position. Whether you are a massage therapist, physical therapist, personal trainer, nurse, doctor, or any other healthcare provider, you’ll need to know anatomical position. However, if you are studying Chinese medicine, acupuncture, or another eastern medicine specialty, you might also see a reference to anatomical position. In that case, it may mean the eastern position. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the limitations of anatomical position? Although having a place to start describing the body is useful, there are certainly some limitations to our idea of describing movement from anatomical position. If you think about how you move around in daily life, it’s probably pretty rare that you would find yourself standing in exactly this position. Perhaps you’re a yoga teacher and have students initiating a movement from lying supine on the floor? Maybe you’re a personal trainer and have clients moving from a hanging position? Real, organic movement begins from all kinds of positions. Anatomical position is useful for gaining an understanding of how things are oriented in the body and what the basic movements are, but at some point you need to see past the constraints of it. Once you’re feeling comfortable with the concept of anatomical position, it’s important to take that idea out into the world of organic movement and apply it there. If you want to learn more about the history of anatomical language and terms, check out [this article](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380415/) in the National Library of Medicine. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/what-is-connective-tissue/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Defining Connective Tissue ![connective tissue](//3dmusclelab.com/wp-content/uploads/2018/08/connective-tissue.jpg) As a movement-based teacher or therapist, part of being able to communicate with other practitioners as well as clients, is knowing specifically what you’re talking about. Terms like [muscles](https://3dmusclelab.com/what-is-a-muscle/), connective tissue, and [fascia](https://3dmusclelab.com/what-is-muscle-fascia/) are all part of the conversation among those practicing movement-based therapies. But what do they mean and how are they related to one another? ## The interrelated human body In our body, nothing works alone. Structures, tissues and systems are all interrelated. We can start to understand the arrangement of interrelation by moving from broader components to more narrow components. For example, we could start with an organism, a human. Within a single organism, there are many interrelated systems. We’re generally familiar with the existence of our circulatory system, as one of the systems in our body, for example. There are organs doing work to keep each system functioning. Within our circulatory system, one organ supporting the function of that system is the heart. Individual organs, like the heart, are composed of tissues. ### Organism (for example, a human) ### System (for example, the circulatory system) ### Organ (for example, the heart) ### Tissue ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Dissecting connective tissue A tissue is a group of similar cells that together perform a common function. There are four types of tissue in the body: - Epithelial tissue - Muscle tissue - Nervous tissue - Connective tissue What defines connective tissue is its components. All types of connective tissue have: - Protein fibers - A ground substance in which the protein fibers are found - Cells This is the most abundant type of tissue in the body and also the most varied. The combination of the type of ground substance, types of protein fibers, and types of cells, result in the wide diversity of tissue types. Different types of connective tissue include: - Cartilage - Bone - Blood - Other types - AND “connective tissue proper” This can get confusing because the category of tissue type and one specific example of that tissue type share a similar name! Connective tissue proper is also referred to as fascia. ## Why is connective tissue important? It is important because it does what its name suggests. It *connects* other tissues, organs, and structures together. In our skin, for example, the surface layer of tissue, the epidermis, is connected to deeper layers of tissue with connective tissue. Ligaments are a type of connective tissue that connect one bone to another at a joint. Tendons are a type of connective tissue that connect muscle to bone. This thread of integration and connection in the body is important to our understanding of how function happens in the body, particularly movement. By starting from the big picture of organism and then zooming in to examine tissue types, we can start to gain more understanding of how integrated the body really is. As movement-based teachers and therapists it’s important to add an understanding of this type of tissue to our big picture of how complex movement can be. When we pick up our foot to take a step, it’s not only the action, tension, and flexibility of muscle tissue that impacts our step. Our connective tissue is also part of the action. ## Want to find out more? You can continue to follow this body trail a little deeper in our related post [What is muscle fascia?](https://3dmusclelab.com/what-is-muscle-fascia/) Find out how connective tissue proper, or fascia, interacts with muscles. For an even deeper dive, check out some of the [resources from the Fascia Research Society](https://www.fasciaresearchsociety.org/resources.php). This tissue type is so important that it has its own research society! The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/knee-hyperextension/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Should I Be Concerned About Knee Hyperextension? ![Knee Hyperextension](https://3dmusclelab.com/wp-content/uploads/2020/01/anatomy-of-knee.jpg) Let’s start by defining hyperextension. This is a word that can be confusing because it can be used in two different ways. The first way that the term hyperextension can be used is to describe a basic, normal movement. Hyperextension is extension past the point of “neutral” when we are standing in anatomical position. So, if I extend my arm at the shoulder joint from a flexed position and return it to my side, I have done extension of the shoulder joint. If I keep going with that movement until my arm is behind my body, I have now technically done hyperextension of the shoulder joint. There is a second way that the term hyperextension can be used, which is to describe the condition of hyperextension. This condition can describe the position of multiple different joints in the body, but is probably most commonly applied to the knee joints and the [elbow joints](https://3dmusclelab.com/elbow-joint-and-forearm/). ## Knee hyperextension Hyperextension of the knee joint means that the shape of the joint itself, where the tibia meets the femur, is extended past where we would consider “neutral” to be when we are standing in anatomical position. The chronic condition of hyperextension of the knee joints might have a genetic predisposition as a result of bone shape, and/or laxity of the tendons and ligaments that surround the knee joint. Postural patterns can also influence a habit of moving the knees to hyperextension. An acute condition of knee hyperextension could result from an accident or injury, and is often sports-related. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## When to be concerned about hyperextension of the knees If you experience a chronic pattern of hyperextended knees that is never retrained, it’s possible for problems to occur such as wearing away cartilage, over-stretching the posterior cruciate ligaments of the knee, or overstretching the gastrocnemius and hamstring tendons. If you have an acute condition of knee hyperextension caused by an accident or sports injury, then there may be more immediate injuries that need attention. Concern about a pattern of hyperextension at the knee joints sometimes comes up in activities where we toward ends of range of motion like [yoga](https://www.yoganatomy.com/hyperextending-the-knees-in-dandasana/) or gymnastics. But even in those activities the issue is really more of a concern when we’re weight-bearing through the knee joint. ## What to do? If you are experiencing the chronic type of mildly hyperextended knees, try cultivating a new pattern. Retrain yourself to maintain a micro bend in the knee joint to keep the surrounding muscles actively holding the knee joint in a healthy place. If you have an acute condition of knee hyperextension caused by a recent accident or sports injury, then you should see an appropriate medical professional for diagnosis and treatment. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/what-is-muscle-fascia/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Understanding Muscle Fascia ![muscle fascia](//3dmusclelab.com/wp-content/uploads/2018/08/what-is-muscle-fascia.jpg) A deeper understanding of how we move requires an understanding of all the components that impact movement. We’re likely familiar with the idea that muscles move bones, but let’s delve a little deeper. While movement is certainly a product of muscles moving bones, there are additional factors that affect the subtleties of movement. One of those is muscle fascia. ## Components and types of fascia Before we get too specific about muscle fascia, let’s review some terms and set the context for where we are in the body when we are talking about fascia, in general. Remember that there are four types of tissue in the body and one of them is [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Within the broader category of connective tissue is the specific type: connective tissue proper, also called fascia. All types of connective tissue proper/fascia have: - Protein fibers: a mixture of collagen, elastin, and sometimes reticulin fibers - A ground substance called hyaluronic acid, in which the protein fibers are found - Cells The specific type of connective tissue proper or fascia is determined by: 1. the amount of protein fibers 2. the type of protein fibers 3. the arrangement of protein fibers Connective tissue proper, or fascia, is divided into loose connective tissue proper (when there are fewer protein fibers) and dense connective tissue proper (when there are more protein fibers). Depending on the type and arrangement of protein fibers, we could get many different types of either loose connective tissue proper or dense connective tissue proper. Ligaments, tendons, and aponeuroses (broad, flat, muscle attachments) are examples of dense connective tissue proper. Adipose tissue (fat) and areolar tissue are examples of loose connective tissue proper. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Diving deeper into muscle fascia We can refer to specific types of fascia, such as “muscle fascia” when we want to talk about connective tissue proper that has a particular arrangement, type, and amount of protein fibers and has a specific role in the body. Muscle fascia is areolar connective tissue with loosely arranged collagen and elastin fibers. It surrounds each layer of muscle tissue and is continuous with the components of a muscle. Because muscles are not separate from the fascia that encases them and each of their components, we reflect the reality of this integrated arrangement by referring to interconnected muscles and fascia as “myofascia”. You might remember that the components of a muscle are arranged in a particular way. Groups of muscle fibers are arranged together in a bundle. Multiple bundles of muscle fibers grouped together are called a fascicle. A bundle of fascicles together make up a whole muscle, for example, the triceps brachii. Each of these components of a muscle is surrounded by a thin sheet of muscle fascia. Each of the muscle fibers is surrounded by fascia (known as endomysium). Each bundle of fibers (a fascicle) is surrounded by fascia (known as perimysium). Each bundle of fascicles (a whole muscle) is surrounded by fascia (known as epimysium). This fascia is interwoven with the connective tissue of the bones themselves, and the ligaments and tendons connecting muscle to muscle and muscle to bone. ## Why is muscle fascia important? You could refer to fascia as the connection component of the body. Fascia is, after all, another way to refer to connective tissue. Fascia is the tissue that connects everything into one big interconnected whole. With this in mind then, you could imagine that tension or length experienced in the muscle is in a relationship with the tension or length in the fascia. Fascia is an important component of maintaining the tensional patterns of the body and can be a part of allowing or restricting movements. A deeper understanding of movement involves not just muscles and bones, but also muscle fascia. Now that you have a picture of how muscle fascia is integrated into the body, see if how you view movement in the body changes. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/scar-tissue/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is The Role Of Scar Tissue In The Body? ![Scar Tissue](https://3dmusclelab.com/wp-content/uploads/2019/04/scar-tissue.jpg) When we “tear” a muscle, we are often told that what is created in the healing process is called scar tissue. If we accidentally cut ourselves, scrape a knee, or otherwise damage our skin, we can often even see the scar that forms as the cut or scrape heals. But, what *is* scar tissue and why does it form? ## Scar tissue is connective tissue When we tear a [muscle](https://3dmusclelab.com/what-is-a-muscle/) like our hamstrings, or sprain an ankle, what we actually tear is one or more layers of [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Scar tissue is also connective tissue. It’s the kind of connective tissue that the body uses to repair the damaged connective tissue. It can form on the surface of the skin, when we scrape a knee for example, and it can also form internally, when we damage a muscle, tendon, ligament, or other soft-tissue structure. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## How is it formed? When we tear a muscle, our body cues specific types of cells called fibroblasts, which make the components of connective tissue, to quickly create new connective tissue to repair the tear. When each layer of fascia in and around our muscles is originally laid down, the fibers all go in the same direction. When we tear [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/) though, the scar tissue is laid down across the torn fibers in a less organized pattern. It is laid down in what is often described as a “cross-hatch” type of pattern. This creates the most secure repair of the damaged area. ## How to work with scar tissue Although the cross-hatching pattern of newly laid-down scar tissue does a great job of repairing the damaged area, it also creates some tension in that same area when the new fibers pull the original connective tissue fibers together so they can heal. Depending on the extent of the injury or damage to the area, the tension caused by the cross-hatching pattern of the newly laid down tissue can impact range of motion and muscle movement. As soon as it is safe to move the injured area (and after you have permission from your doctor if you have a more serious injury), the best way to begin to realign the scar tissue fibers with the surrounding fascia, and reduce the tension in the area, is to gently move the area. If you have a serious injury, the medical professionals who are overseeing your care will recommend physical therapy or other movement therapy that’s appropriate for your situation. Additionally, there are [types of manual therapy](https://wheelerfascialwork.com/scarwork/) that can help realign those cross-hatching fibers. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/temporomandibular-joint-disorder/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is Temporomandibular Joint Disorder? ![Temporomandibular Joint Disorder or TMJ Disorder](https://3dmusclelab.com/wp-content/uploads/2024/05/tempromandibular-joint.jpg) Temporomandibular joint disorder is one of the most common reasons for jaw pain aside from acute trauma issues, like a car accident or fall. However, many people are confused about what this disorder actually is. In this article, I’ll explain first what the temporomandibular joint is. Then I’ll explain further what both function and dysfunction include at this important joint. Read on to learn more. ## What is the temporomandibular joint? The temporomandibular joint is where a depression in the inferior part of the temporal bone, called the glenoid fossa (or sometimes the mandibular fossa) of the temporal bone, meets a bony protrusion, called the mandibular condyle, on the superior end of the branch of bone (ramus) of your mandible (jaw bone). You have two of these joints, one on each side of your jaw. It’s a hinge type of [synovial joint](https://3dmusclelab.com/synovial-joint/) that includes an articular disc to help manage force transmission and movement at this joint. This joint is critical for opening and closing your jaw, like when you’re chewing or speaking. The opening and closing movements are called elevation and depression, anatomically. In addition to those movements, this joint allows the jaw to move forward (protraction) and back (retraction), and it also moves the jaw from side to side, called right and left lateral deviation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Bones to know There are many small, interestingly-shaped bones that come together to create the complex architecture of our jaw and cranium. In this article, we’ll focus on two bones in particular, the temporal bone and the mandible. These are bones most people are familiar with, even if they don’t know their names. Your temporal bone is a large bone at the side of your skull. It’s narrower at the distal end. But, from these small more pointed areas, it widens out into a rounded shape that occupies most of the space on the side of your head. You’re probably familiar with the upper part of this bone as your “temple.” It’s that area you might massage a bit if you’ve been sitting at the computer too long. Your mandible is your jawbone. It’s the bone that your lower set of teeth are set within. ## Muscles of the temporomandibular joint The main muscles that are important for moving the temporomandibular joint are the [muscles of mastication](https://3dmusclelab.com/jaw-muscles/) (chewing). Those include the masseter, temporalis, lateral pterygoids, and the medial pterygoids. Some of the muscles of the hyoid group (digastric, geniohyoid, and mylohyoid) also assist with some of the movements at the temporomandibular joint. ## Temporomandibular joint disorder The temporomandibular joint is functioning in a healthy way when it is allowing all the types of functional movement that should be available at that joint without causing pain or discomfort. When the temporomandibular joint is malfunctioning, then we can have any of the collection of disorders classified as temporomandibular joint disorder. Temporomandibular joint disorder is the general name for any of the collection of particular symptoms of dysfunction at this joint. The disorders are sometimes loosely grouped into three categories. One category of disorder is pain or dysfunction in the myofascial components of the TMJ. Another category of disorder is a malfunction of, or other issue with, the temporomandibular joint itself. Finally, some medical sources consider headache-related TMJ disorders to be their own category. ## Symptoms of temporomandibular joint disorder The most common symptoms of this group of issues with the temporomandibular joint are pain and dysfunction of the jaw. Pain might show up in the jaw muscles or the joint itself. Some people experience pain in the face, [neck](https://3dmusclelab.com/the-deep-neck-muscles/), or even in areas more distant from the TMJ, such as the [shoulders](https://3dmusclelab.com/shoulder-joint-in-movement/) and back. Headaches are also a symptom often associated with this group of disorders. Dysfunction of the joint often includes clicking, popping, or locking of the joint. ## Causes of TMJ disorder The causes of TMJ disorders are mostly unknown. There are cases when an acute injury such as an accident results in a temporomandibular joint disorder. However, the larger majority of cases seem to arise from no one specific cause. While some research has found morphological changes in the TMJ and surrounding [myofascia](https://3dmusclelab.com/what-is-muscle-fascia/), it’s unclear whether the morphological changes were a result of a TMJ disorder or the cause of it. Research suggests that TMJ disorder often results from several interrelated factors that include psychological contributors such as stress as well as physical causes. Soft tissue issues such as an imbalance in tension between the [musculature](https://3dmusclelab.com/what-is-a-muscle/) on the two sides of the head, [neck](https://3dmusclelab.com/neck-muscles-superficial/), and jaw, as well as myofascial trigger points, can also contribute to symptoms that fit within the category of TMJ disorder. ## Diagnosis of temporomandibular joint disorder If you are experiencing TMJ disorder symptoms, of course, seek out a full assessment from a medical professional. Diagnosis tools vary among individual medical practitioners. Some use the recently created diagnostic tool, the Diagnostic Criteria for Temporomandibular Disorders. That tool includes both a physical exam as well as a screen for other related factors such as psychological factors. Regardless of the specific tool used, most exams will include some combination of a physical exam and an intake to gather information about other related potential contributing factors. Depending on your particular symptoms and their severity, your medical professional might also recommend getting some images to help diagnose your specific TMJ disorder. Common types of imaging include MRI, CT scan, and more recently, ultrasounds. ## Treatment of TMJ disorder The focus of temporomandibular joint disorder treatment is on eliminating pain, restoring function, and minimizing any potential long-term issues that could arise from dysfunction. Those might be issues such as morphological changes to the jaw or soft tissue. Initial treatments focus on eliminating pain by changing daily habits that contribute to pain. That includes things like eating softer food to rest the jaw and chewing muscles, not chewing gum, and addressing issues like tooth-grinding, etc. Cold or warm packs can also help reduce pain. Non-steroidal anti-inflammatory (NSAID) options like many over-the-counter pain relievers might also be recommended to reduce pain in the short term. Some types of TMJ disorders resolve without any further treatment needed. However, depending on your particular type of TMJ disorder, your doctor might also recommend manual therapies, physical therapy, and or splinting of the jaw to reduce pressure on the temporomandibular joint. As a last resort, and only in the case of certain types of temporomandibular joint disorders, your doctor might suggest surgery. ## Conclusion Temporomandibular joint disorders are a group of disorders that share the symptoms of TMJ pain and dysfunction. There is no single specific cause for this array of disorders. What is most likely is that multiple interrelated factors interact to result in the symptoms associated with TMJ pain and dysfunction. If you are experiencing symptoms of TMJ disorders, seek a full assessment from an appropriate medical professional. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [National Institute of Health. (Accessed 2023, May). *TMD (Temporomandibular Disorders)*. National Institute of Dental and Craniofacial Research, National Institute of Health. https://www.nidcr.nih.gov/health-info/tmd](https://www.nidcr.nih.gov/health-info/tmd) [Maini K, Dua A. Temporomandibular Syndrome. [Updated 2023 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551612/](https://www.ncbi.nlm.nih.gov/books/NBK551612/) [Palmer, J. and J. Durham. 2021. Temporomandibular disorders. British Journal of Anaesthesia Education. 21(2):44-50.](https://pubmed.ncbi.nlm.nih.gov/33889429/) [Park, B-R., J-A. Gim, and K-W. Baek. 2023. Improvement of the pain of temporomandibular disorder in parts of the human body through temporomandibular joint correction treatment. Physikalische Medizin, Rehabilitationsmedizin, Kurortmedizin. 33:352–357.](https://www.thieme-connect.com/products/ejournals/pdf/10.1055/a-1840-9458.pdf) [Pihut, M., G. Andrzej, R. Obuchowicz, and K. Chmura. 2022. Influence of ultrasound examination on diagnosis and treatment of temporomandibular disorders. Journal of Clinical Medicine. 11:1202. 9pgs.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911463/) --- Source: https://3dmusclelab.com/brachial-plexus/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Why Is The Brachial Plexus Important? ![The Brachial Plexus](https://3dmusclelab.com/wp-content/uploads/2020/01/brachial-plexus.jpg) Nerves in our body function to relay information. We have nerves that are responsible for the sensations we feel and nerves that cue our muscles to move. More specifically, it is our somatic nervous system that makes these connections. The nerves that go from our brain and spinal cord to our muscles and skin make up our somatic nervous system. One special bundle of nerves that is part of that system is the brachial plexus. The brachial plexus is a bundle of nerves that start from the spinal cord in the cervical portion of the spine and continue branching to feed the whole arm. These nerves are responsible for innervating all of the muscles of the arm. They contribute to our feelings and sensations in the arm, as well as innervating our muscle movement. The brachial plexus is an anatomical structure that often comes up around pain, sometimes shoulder, neck, or hand and wrist pain. It’s an important structure to be aware of as it can interact with muscle tension to present a variety of symptoms of sensation, like pain, tingling, or numbness. In more extreme cases, pressure on this bundle of nerves can cause the neurogenic (related to nerves) type of thoracic outlet syndrome. That happens when the space between the clavicle and the first rib is reduced to the point that compression on all or part of that nerve bundle as it comes through the thoracic outlet, causes symptoms like pain, tingling, and/or numbness in the shoulders and neck, and possibly even the arm and/or fingers. ## Where is the brachial plexus? Generally, the nerves of the brachial plexus come out from the [cervical spine](https://3dmusclelab.com/exploring-the-spine/) between the anterior and middle scalene muscles to run over the first and second rib and under the clavicle. They then run deep to the pectoralis minor muscle and continue to branch as they feed various parts of the arm. The specific path of the nerves have some variability from person to person (Golarz, 2020; Leijnse et al., 2019). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Why is the brachial plexus sometimes associated with pain or tingling? The path of the nerves that make up the brachial plexus provide many opportunities for either bony structures or muscles to put pressure on these nerves. Bony structures like the cervical vertebrae, the clavicles, and sometimes even the upper ribs, can put pressure on the nerves of the brachial plexus. Pressure can also be put on these nerves by short or tight muscles, like pectoralis minor or the scalenes. Pressure from tight muscles or bony structures on these nerves can cause those symptoms we mentioned earlier: pain, tingling, numbness, and other nervy sensations. Conclusion Nerves provide the connections between our brain and spinal cord and the sensations we feel and the movements our muscles do. One special bundle of nerves, important for sensation and movement in our shoulders, arms, and hands is the brachial plexus. This particular nerve bundle often gets attention when either a bony or soft tissue structure puts pressure on it. In that situation we might experience pain, tingling, or numbness. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Golarz, Scott. 2020. Anatomic variation of the phrenic nerve and brachial plexus encountered during 100 supraclavicular decompressions for neurogenic thoracic outlet syndrome with associated postoperative neurologic complications. Annals of Vascular Surgery. 62:1615-5947.](https://www.ncbi.nlm.nih.gov/pubmed/31207398) [Leijnse, J.N., B.S. de Bakker, and K. D’Herde. 2019. The brachial plexus – explaining its morphology and variability by a generic developmental model. Journal of Anatomy. doi:10.1111/joa.13123.](https://www.ncbi.nlm.nih.gov/pubmed/31814126) --- Source: https://3dmusclelab.com/what-is-the-gait-cycle/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is The Gait Cycle? ![Walking And The Gait Cycle](https://3dmusclelab.com/wp-content/uploads/2023/09/gait-cycle.jpg) The gait cycle is the technical name for how we walk. Walking is so fundamental to our daily activities that we often it for granted. But walking, or gait, requires a complex series of actions. Many books have been written on the gait cycle and the nitty gritty details are beyond the scope of this article. But it can be helpful to our understanding of how we do any kind of [functional movement](https://3dmusclelab.com/functional-movement/) to take a look at how we walk. So, in this article, I’ll give you a broad overview of what happens when we walk. ## Breaking down the gait cycle A gait cycle, also called a “full stride,” is composed of taking one step with each foot. It’s broken down into two main pieces. We are in the “stance” period when our striding food is connected with the ground. The “swing” period occurs when that foot is in the air. The brief moment when both feet are touching the ground is called the “double limb support” phase. Each of those subsections of a gait cycle can be broken down further. The stance phase begins with heel strike, then continues with weight-acceptance, followed by a mid-stance and then a late-stance phase. We spend about 60% of our gait cycle in the stance period. The swing period starts with toe-off and then continues through early swing, mid-swing, and late swing. We spend about 40% of our gait cycle in the swing phase. Let’s take a walk through the gait cycle to learn more about what happens during each of these phases. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Taking a walk A gait cycle technically begins with the heel strike. That’s the moment that the heel of our front foot meets the ground after we’ve swung that foot through. Then we shift our weight onto that leg (the weight-acceptance phase) and roll through our foot as we shift our body weight forward to complete the mid- and late-stance phases. During these portions of the stance phase, we pick our heel up and then our mid-foot as we shift our weight forward and roll through our foot. The momentum of our body going forward then brings us to toe-off on that same foot. That’s the moment that we lift our toes off the ground and our foot is in the air. We then swing that leg forward through the early, mid-, and late-swing phases to arrive back at heel strike when the heel of that same foot meets the ground again. ## Why is gait more complex than static posture? There are many forces that influence how we walk (and move in other ways too) that are less involved with maintaining our static posture. While gravity is active in both cases of course, during movement we also interact with momentum and something called the ground force reaction. This is the force created by the ground in response to our body contacting it. So, for example, when our foot hits the ground at heel strike, there is a force going down through our body into the ground created by our movement, and there is a reciprocal force that is generated by the ground in response that moves back up into our body. Additionally, we have skeletal, [muscular](https://3dmusclelab.com/what-is-a-muscle/), and [fascial](https://3dmusclelab.com/what-is-muscle-fascia/) ([connective tissue](https://3dmusclelab.com/what-is-connective-tissue/)) components that all come together to support a healthy gait. The ideal gait involves our whole body. While we might think of walking as something that mostly happens in our lower body, that isn’t really true. In fact, the more we involve the whole body, the more we can rely on the fascial spring loading of winding and unwinding, and the less muscular effort is necessary. In every plane, our body is pre-tensioning and then using that kinetic energy to move us forward. ## What is the body doing when we walk? ### Sagittal plane movement Our body is moving three-dimensionally, of course when we move. This also makes it more complicated to describe what our body is doing compared to describing static posture. If we start at the foot and work our way up the body, our first action is connecting our heel with the ground. Then we roll over the calcaneus (our heel bone), through the [ankle joint](https://3dmusclelab.com/exploring-the-ankle-joint/), through the forefoot, and then through the toes. We coordinate that with [knee](https://3dmusclelab.com/knee-joint/) extension, hip extension, and spinal extension to propel our body forward. As we roll through our foot from heel strike to toe-off, [our pelvis](https://3dmusclelab.com/exploring-the-pelvis/) on that side goes from a slight posterior tilt to a slight anterior tilt. On the other side, our pelvis does the opposite. As we swing our leg through, our pelvis on that side goes from a slight anterior tilt to a slight posterior tilt. Movement of both sides of our pelvis at the [sacroiliac joints](https://3dmusclelab.com/sacroiliac-joint/) allows this back-and-forth motion of the pelvis to happen as we walk. ### Frontal and transverse plane movement Along with our movement in the forward-backward sagittal plane, we also move in the frontal plane and rotate in the transverse plane to complete our walking pattern. As we step forward with one foot, meet the ground with our heel, and start to roll into our foot, our pelvis laterally tilts toward our weight-bearing leg, as we shift our weight from one leg to the other. And then as we take another step forward, our pelvis tilts laterally again in the other direction. To allow and stabilize the action of shifting our weight as we walk, we laterally flex our lumbar [spine](https://3dmusclelab.com/exploring-the-spine/) toward the weight-bearing leg. Our [abductors](https://3dmusclelab.com/lateral-hip-muscles-in-movement/) (our [lateral gluteals](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/)) then have to lengthen a bit in order to let that hip drop. At the same time, our [adductors](https://3dmusclelab.com/exploring-the-adductor-muscles/) on the other leg [engage](https://3dmusclelab.com/muscle-contractions/) as we lift the other side of our pelvis. As we step our foot forward, our pelvis also externally rotates and our upper thoracic spine and [shoulder girdle](https://3dmusclelab.com/shoulder-girdle/) counterrotate in the other direction. ## What influences our gait cycle? Since walking is so fundamental to many of our daily tasks, we might think that everyone just naturally learns to walk efficiently. But actually, there are lots of influences that alter our gait cycle. Initially, we learn to walk by modeling the people in our environment. Those people, our parents and other caregivers, almost certainly have their own gait pattern. And that pattern is influenced by genetics, including things like relative bone length, joint angles, flexibility, and other factors. It’s also moderated by activities that we do. What we do with our body creates patterns in it and walking is no exception to that. Repetitive work tasks, habits, and sports/leisure activities can also affect how we walk. ## What might disrupt our gait cycle? Injuries to the lower body will obviously have some effect on how we walk. Because gait itself is so complex, understanding the effects of injuries on walking is all the more complicated. Perhaps less obviously, injuries to the upper body also have the potential to affect how we walk, depending on the amount, duration, and type of compensations that we make to adapt to the injury. Surgical procedures like knee and hip replacements especially affect walking. The stability and function of the replaced joint may not be the same as the other side, creating altered walking patterns. ## Conclusion Walking is one of our most basic functional movements. We walk to complete many of our daily activities. The ability to walk is a foundation for many sports and leisure activities as well. While it is a complex multiplanar movement, understanding the gait cycle can help us better understand so many other types of movement. This fundamental series of movements is the base of much of the other movements we engage in. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## Resources Chaitow, L. and J. DeLany. 2011. Chapter 3: Gait analysis. *In* Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition). New York, NY: Churchill Livingstone Publishing. Earls, J. 2020. Born to Walk: Myofascial Efficiency and the Body in Movement. (Second Edition) Berkeley, CA: North Atlantic Books. [Hu, X., N. Zheng, W.-C. Hsu, J. Zhang, H. Li, Y. Chen, K. Dai, and T.-Y. Tsai. 2020. Adverse effects of total hip arthroplasty on the hip abductor and adductor muscle lengths and moment arms during gait. Journal of Orthopaedic Surgery and Research. 15:315-322.](https://pubmed.ncbi.nlm.nih.gov/32787875/) --- Source: https://3dmusclelab.com/shoulder-girdle/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Structures Make Up The Shoulder Girdle? ![shoulder girdle](https://3dmusclelab.com/wp-content/uploads/2019/05/shoulder-girdle.jpg) The arrangement of bones and muscles in the shoulder girdle allows us to do a wide variety of movement, possibly a greater variety of movement than anywhere else in the body. Let’s explore the bones and muscles that make up the shoulder girdle, which is also called the shoulder complex. ## Bones in the shoulder girdle The shoulder complex includes several different bones. Some references refer to the shoulder complex as composed of the scapula, clavicle, and sternum. Others include the humerus, scapula, and the clavicle. It makes sense to me to include the humerus as part of the shoulder girdle, as the shoulder joint itself (the glenohumeral joint) is where the humerus and scapula meet. The more important point to take away is that the movement and position of the scapula will directly impact the movements available at the glenohumeral joint (shoulder joint) and vice versa. They are intimately linked. Specifically, the shoulder joint itself, called the glenohumeral joint, refers to the joint where the head of the humerus (the upper arm bone) meets the glenoid fossa of the scapula. However, the position and movements of the scapula affect the movements of the humerus, so all of these structures are often referred to collectively as the shoulder girdle or shoulder complex. We have potentially four bones that could be considered part of the shoulder girdle or shoulder complex: - The humerus = the upper arm bone - The scapula = the shoulder blade - The clavicle = the collarbone - The sternum = the breastbone ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Joints in the shoulder girdle We have three or four (depending on how you describe them) joints where movement can happen in the shoulder girdle: - The glenohumeral joint = shoulder joint where the humerus meets the glenoid fossa of the scapula - The acromioclavicular joint = where the acromion of the scapula meets the clavicle - The sternoclavicular joint = where the clavicle meets the sternum - The scapulothoracic joint = some references also refer to the scapulothoracic joint. Although not a true joint, this is where the scapula meets the ribcage. The sternoclavicular joint is particularly important as this is where the shoulder girdle, which is part of the appendicular skeleton, attaches to the axial skeleton. ## Movements of the shoulder girdle The individual movements of each joint of the shoulder complex combine together to create the variety of movement that is possible at the shoulder girdle as a whole. Movements of the humerus at the glenohumeral joint include: flexion, extension, abduction, adduction, lateral rotation, and medial rotation. We discussed the movements of the scapula already in the article on exploring the scapula. Movements of the scapula include: elevation, depression, protraction, retraction, upward rotation, downward rotation, and tilting. The movements of the clavicle are similar to the scapula. The movements of the clavicle include: elevation, depression, protraction, retraction, upward rotation, and downward rotation. Some researchers have suggested that, evolutionarily, our upper extremities evolved to place the hands in space, while the lower extremities evolved to take us places, i.e. to walk and run. With this idea in mind then, we can see why such a range of mobility in all planes of space would be necessary for the shoulder girdle, while less mobility, but more strength and power in the hip joints, would support walking and running. The shoulder girdle uses multi-joint, three-dimensional movements to position the hand. The fine movements we take for granted everyday, from typing and writing, to using our cell phone or playing the piano, all originate with movements of the shoulder girdle which position the forearm, and ultimately the hand and wrist. When we raise our arm overhead, this motion does not come from the glenohumeral joint alone. The scapula and clavicle also move to allow the arm to be elevated (Ludewig et al., 2009). In fact, the full kinetic chain from the axial skeleton to the hand is really: thorax/ribcage → scapula → upper arm → lower arm → hand (van Andel et al., 2008). You can see why such variety of movement is possible in the shoulder girdle when we combine all these uniquely moving pieces. If you want to read more about the shoulder girdle check out this related article: [Exploring The Scapula](https://3dmusclelab.com/scapula/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Calais-Germain, B. 2007. The trunk. In J. O’Connor and A. Kaplan (Eds.), *Anatomy of Movement*. (pgs 30-100) Seattle, WA: Eastland Press. Ludewig, P.M., V. Phadke, J.P. Braman, D.R. Hassett, C.J. Cieminski, and R.F. LaPrade. 2009. Motion of the shoulder complex during multiplanar humeral elevation. The Journal Of Bone And Joint Surgery. 91-A(2):378-389. van Andel, C.J., N. Wolterbeek, C.A.M. Doorenbosch, D. (H.E.J.) Veeger, and J. Harlaar. 2008. Complete 3D kinematics of upper extremity functional tasks. Gait And Posture. 27:120-127. --- Source: https://3dmusclelab.com/what-happens-when-we-stretch-muscles/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Really Happens When We Stretch Our Muscles? ![What Is Stretching?](https://3dmusclelab.com/wp-content/uploads/2023/02/muscle-stretch.jpg) Stretching muscles is something that we often do without even thinking about it. You likely stretch a bit when you wake up in the morning or when you get up from sitting or standing in one position for a while. If you are involved in a sport, you might do specific stretches to help reduce tension or maintain range of motion in your body. But what happens, anatomically, when we stretch? In this article, we’ll look into what the research says about what might be happening in our body when we stretch. We’ll also take a look at why and how to stretch. ## What is stretching? Stretching, most generally, is lengthening [muscles](https://3dmusclelab.com/what-is-a-muscle/) with the intention of increasing range of motion. More specifically, there are several common kinds of stretching. Static stretching is something most people are familiar with. This is the simplest version where you reach and hold a shape for a few breaths or more, then release. There is also dynamic stretching, which describes stretching your muscle while moving. Another type is ballistic stretching, which involves adding a little bounce while trying to lengthen a muscle. And another type that has become more common is proprioceptive neuromuscular facilitation (PNF) technique. This type of stretching follows a protocol of alternating between stretching, then [isometrically contracting](https://3dmusclelab.com/muscle-contractions/) the muscles against resistance for a few seconds, then stretching again. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Mechanisms The real answer to the question, what happens when we stretch muscles, is we don’t know. What’s most likely true is that we have more than one mechanism working together to create the end result of increased range of motion. Much of the research looking for mechanical changes from stretching has been inconclusive. One review study reported that muscle length changed after short-term stretching protocols, but the change in muscle length was temporary (Holzman Weppler and Magnusson, 2010). Other research has suggested that the mechanisms of change in [joint](https://3dmusclelab.com/synovial-joint/) range of motion after we stretch are actually based on sensation tolerance happening in our nervous system (Freitas et al., 2018; Holzman Weppler and Magnusson, 2010; Ben and Harvey, 2010). It’s possible that as our tolerance to stretch sensation increases so does our available range of motion. ## Why stretch? Regardless of how we do it, stretching is an effective way to increase range of motion. And maintaining a healthy range of motion is important for functional movement. If we do sports or athletic activities that build certain patterns of strength, maintaining a balance of flexibility is important for being able to access the strength that we have and for reducing the chances of injury. If we [sit a lot, at a desk](https://3dmusclelab.com/trapezius-computer-posture/), then we can benefit from stretching too. We can feel stiff as a result of both activity and inactivity. And, as we age, we all tend to get stiffer and dry out. Stretching can be helpful for ameliorating the effects of aging. We can’t avoid getting older, but we can do things like stretching to care for our bodies and slow the effects. A recent review study even found that stretching may have benefits for our cardiovascular system (Wong and Figueroa, 2019). ## How to stretch? Research suggests that all of the types of stretching effectively increase range of motion (Thomas et al., 2018). Some individual studies have found one particular type of stretching to be more effective than another type on a particular muscle group. For example, one review paper found that static stretching increased range of motion more than ballistic or PNF techniques (Thomas et al., 2018). But a different study found the opposite, that active stretching resulted in greater range of motion than static stretching (Meroni et al., 2010). So, it’s hard to generalize from these studies. It may be that different muscle groups respond differently to types of stretching. As far as the effectiveness of stretching on range of motion, frequency seems to matter more than the style or technique of stretching. A recent review paper reported that weekly frequency of stretching was positively related to range of motion (Thomas et al., 2018). As the frequency of weekly increased, the range of motion gains increased as well. They did not find a relationship between duration of an individual session of stretching and gains in range of motion (Thomas et al., 2018). ## Conclusion Stretching is something that usually feels good and is good for us! Regardless of which type of stretching we choose to do, it’s likely going to be effective at increasing our range of motion. And it may have other positive effects throughout our body. These are good reasons to add some stretching to your movement routine. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Ben, M. and L.A. Harvey, 2010. Regular stretch does not increase muscle extensibility: a randomized controlled trial. Scandinavian Journal of Medicine and Science in Sports. 20:136-144.](https://pubmed.ncbi.nlm.nih.gov/19497032/) [Freitas, S. R., B. Mendes, G. Le Sant, R.J. Andrade, A. Nordez, Z. Milanovic. 2018. Can chronic stretching change the muscle-tendon mechanical properties? A review. Journal of Medicine and Science in Sports. 28:794-806.](https://pubmed.ncbi.nlm.nih.gov/28801950/) [Holzman Weppler, C. and S.P. Magnusson. 2010. Increasing muscle extensibility: A matter of increasing length or modifying sensation? Physical Therapy. 90(3):438-449.](https://pubmed.ncbi.nlm.nih.gov/20075147/) [Meroni, R., C.G, Cerri, C. Lanzarini, G. Barindelli, G.D. Morte, V. Gessaga, G.C. Cesana, and G. de Vito. 2010. Comparison of active stretching technique and static stretching technique on hamstring flexibility. Clinical Journal of Sports Medicine. 20(1):8-14.](https://pubmed.ncbi.nlm.nih.gov/20051728/) [Thomas, E., A. Bianco, A. Paoli, A. Palma. 2018. The relation between stretching typology and stretching duration: The effects on range of motion. International Journal of Sports Medicine. 39:243-254.](https://pubmed.ncbi.nlm.nih.gov/29506306/) [Wong, A. and A. Figueroa. 2019. Effects of acute stretching exercise and training on heart rate variability: A review. Journal of Strength and Conditioning Research. 35(5):1459-1466.](https://pubmed.ncbi.nlm.nih.gov/30789584/) --- Source: https://3dmusclelab.com/5-tips-for-learning-kinesiology/ Author: David Keil · Updated: 2025-12-17 How We Learn # 5 tips for learning kinesiology ![5 Tips For Learning Kinesiology](//3dmusclelab.com/wp-content/uploads/2018/05/5-tips-learn-kinesiology.jpg) ## 1. Get motivated! Why is it that you want to learn about muscles and movement? Learning any new topic or skill can seem daunting at first, but if it has value to you, then you’re more likely to stick with it. Take a moment to think through the different ways that learning [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) will be valuable to you. Are you interested in better understanding how your own body works? Are you looking to expand your skill set and knowledge as a practitioner that you can offer to clients? Are you working towards a degree or certification and need to learn kinesiology to complete it? Any of these might be motivating for you. You probably have even more reasons why you want to be learning kinesiology. Remind yourself of why you are learning this new topic to help yourself stay motivated. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## 2. Vary the method of learning Take in new information in more than one way. Experiment with reading, watching, listening to, and applying the new information. See which combination works best for you. You may want to watch a video or read about new information the first time you are encountering it. Then, as you go through the information a second time, try taking notes or thinking through the application of that information. For example, the first time you read or hear about the quadriceps muscles, you could simply take in this new material. However, to help you organize the information, the second time you hear or read about the quadriceps, you might take some notes about what you are hearing as the key points, or physically draw the key points for a more visual record. ## 3. Single-tasking Focus on the learning and set aside distractions. [Research shows](http://www.nytimes.com/2013/05/05/opinion/sunday/a-focus-on-distraction.html) that it takes an average of 25 minutes to refocus on a task when you have been distracted by something else, even if the distraction only lasted for a few moments. Try turning off your devices and closing extra tabs on your laptop while you are focused on learning kinesiology. Make efficient use of your study time, by making studying your priority during that period. ## 4. Pace yourself Take breaks during a learning session. Don’t try to learn everything in one day! Set yourself up for success by planning your time in a way that you can focus on small pieces of new information at a time. Plan ahead and set aside shorter periods of time on multiple days, so you can focus on a manageable unit of new information in each study session. ## 5. Repeat and review Research shows that we need to take in new information more than once to really understand it. Reviewing new material is critical to connecting all the disparate pieces in a way that helps you make sense of the new topic. (Check out this [article from the American Psychological Association](http://www.apa.org/science/about/psa/2016/06/learning-memory.aspx) to learn more about the importance of information review and retrieval for learning.) So, for best learning retention and depth of understanding: review, review, review! You could make flashcards for yourself, as the act of writing down the information will help you review it. You can use your notes, flashcards, or quizzes to quiz yourself and have a friend quiz you. Try rewriting your notes in a form that helps the material make sense to you, perhaps by rewriting your notes in outline form or as a large web diagram. If you need some ideas, check out [mindmapping.com](http://www.mindmapping.com/). ## Bonus tip Try explaining concepts that you want to understand better to a friend. You really have to understand a subject well in order to explain it to others. Sharing your new knowledge out loud to a friend will help that information stick in your memory, and it will make you aware of any gaps in the information where concepts haven’t quite gelled yet. This is especially true of learning kinesiology. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/how-we-learn/ Author: David Keil · Updated: 2025-12-17 How We Learn # How We Learn: What Is Our Process For Learning New Information? ![How we learn](https://3dmusclelab.com/wp-content/uploads/2019/01/how-we-learn.jpg) Learning, and specifically how we learn, has been in the news. From [Time Magazine](http://ideas.time.com/2011/10/12/the-science-of-how-we-learn/) to [Forbes](https://www.forbes.com/sites/quora/2017/11/20/how-do-people-learn-most-effectively/#726872901f05) to the [New York Times](https://www.nytimes.com/2005/01/16/education/edlife/how-we-learn.html), everyone is curious about how we learn. While we might associate learning with school, learning is really a lifelong adventure. Whether it’s taking up a new hobby or learning the new menus on your iPhone, we’re learning all the time. But how does it happen? What are the processes involved in how we learn? ## The short-term or working memory One of the first systems in our brain involved with learning new information is our short-term or working memory. This system can hold information for only a very brief period of time, researchers suggest 10-15 seconds. The working memory can also hold only so much information at one time. If we want to retain some new piece of information, then we need to hold onto this new information in our working memory long enough to use it. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Moving information to long-term memory Once we have taken in new information, repetition and engagement with the information is required to keep that information around for the long-term. In order to maintain and integrate new information, we need to interact with it soon after placing it in our working memory. If we engage with the newly acquired information, it will move to long-term memory. If we establish the new information in our long-term memory, then we’ll begin to integrate new concepts into our overall understanding of a topic. ## What this means for learning kinesiology - Avoid trying to cram. You can only retain and process so much information at one time. For better retention, plan ahead and allow yourself time to learn a little bit at each study session. - Avoid splitting your attention when trying to learn new things. Trying to split your attention can overload your working memory and result in low retention of new information. It’s better to turn off distracting devices and close down those other open tabs on your laptop while studying. - Review new information multiple times and engage with it in different ways. Read, listen, and apply the concepts for better retention. ## How our course at 3D Muscle Lab can help you learn kinesiology If you’re struggling to [learn the basics of kinesiology](https://3dmusclelab.com/5-tips-for-learning-kinesiology/), we can help. Our course is designed to present the material in short manageable chunks, so your short-term memory isn’t overloaded in one session. We present the information in multiple different ways and include quizzes for reviewing each topic. You have the opportunity to engage with each unit as many times as you need, so you can move your newly acquired kinesiology knowledge to your long-term memory where you can apply it to your work. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Cowan, N. 2009. What are the differences between long-term, short-term, and working memory? Prog. Brain. Res. 169: 323-338.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657600/) --- Source: https://3dmusclelab.com/web-based-learning/ Author: David Keil · Updated: 2025-12-17 How We Learn # Make Web-based Learning Work For You ![web based learning](https://3dmusclelab.com/wp-content/uploads/2019/07/online-training.jpg) ## What is web based learning? Web based learning, also called e-learning or online learning, uses the internet or internet-based technology to create a learning environment. It often uses multimedia approaches. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Benefits of a web based learning platform There are many benefits of learning from a web based learning platform. As the student user, in an online environment, you have the opportunity to control the pace at which you interact with new material. You can spend more time on concepts that you find more challenging and spend less time with material that you have already studied and only need to review. There is more opportunity for repetition of new material when you are moving through a course at your own pace and that repetition can be tailored to your learning needs. In a web-based learning situation you can adjust the timing of the course to fit your schedule. Additionally, web based courses aren’t limited to those who have local physical access to the course location. They can be made available to far more people who potentially would not otherwise have access to the course. Web based technologies are varied and include many different types of teaching tools and learning platforms. This means that a wide diversity of approaches can be used to teach course content. Diverse approaches to presenting the material increase the likelihood that more students will understand and retain what they’re learning. ## How to adapt your personal learning style to web-based learning Web-based learning can affect your [strategies for studying a new topic](https://3dmusclelab.com/how-we-learn/) or concept. Think about some times when you successfully learned something new. What were your strategies? What worked for you? What struggles did you have? How you successfully translate your learning style to a web-based learning environment depends on your own learning style. If you are independently motivated then moving at your own pace may work very well for your style of studying new concepts. If you find that you need more external motivation and some accountability, then you may need to take the time to create that for yourself in order to get the most out of an online learning environment. It could be as simple as mapping out on a calendar when you plan to complete each unit of a whole course, or you could set up email reminders to keep yourself on track. In a web-based learning environment, you have many different options for how you interact with course material. This is another good place to examine what your own [learning style](https://3dmusclelab.com/whats-your-learning-style/) is and what works best for you. You can spend more time on the ways that you take in information more easily. Whether you prefer to watch a video, read text, or listen, emphasize what works best for you. At 3D Muscle Lab we help you [learn your muscles](https://3dmusclelab.com/5-tips-for-learning-kinesiology/) in an online learning environment. You can take the course when it’s convenient for you and you can move at your own pace through the material. We offer you a chance to see, hear, and do, as well as read and review. Take a look at our free course unit to see what we offer. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Cook, D.A., S. Garside, A.J. Levinson, D.M. Dupras, and V.M. Montori. 2010. What do we mean by web-based learning? A systematic review of the variability of interventions. Medical Education in Review. 44:765-774.](https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2923.2010.03723.x) [Chumley-Jones, H.S., A. Dobbie, C.L. Alford. 2002. Web-based learning: sound educational method or hype? A review of the evaluation literature. Academic Medicine. 77(10):S86-S93.](https://journals.lww.com/academicmedicine/Fulltext/2002/10001/Web_based_Learning__Sound_Educational_Method_or.28.aspx) [Wasim, J., S.K. Sharma, I.A. Khan, J. Siddiqui. 2014. Web based learning. Journal of Computer Science and Information Technologies. 5(1):446-449.](http://ijcsit.com/docs/Volume%205/vol5issue01/ijcsit2014050194.pdf) #### Related Posts --- Source: https://3dmusclelab.com/npcp-anatomy-requirements-2027/ Author: David Keil · Updated: 2026-09-17 How We Learn # What the NPCP anatomy requirement actually asks for in 2027 ![A curriculum document and calendar on a desk, representing Pilates teacher training programs reviewing their curriculum ahead of the January 2027 NPCP deadline](https://3dmusclelab.com/wp-content/uploads/2026/09/npcp-anatomy-requirements-2027.webp) If you run a Pilates teacher training, there’s a date worth putting in your calendar: **January 1, 2027.** That’s when the National Pilates Certification Program’s updated eligibility requirements take effect, and they change how parts of your curriculum can be delivered. The short version: most of your program needs more live contact than it used to. Anatomy doesn’t. ## What’s actually changing NPCP’s current rule allows the [full 450](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/anatomy-hours-pilates-teacher-training/) hours of a comprehensive program to be delivered live or live-virtual. From January 1, 2027: - **Pilates Repertoire** must include an in-person component - **Special Populations** must include an in-person component - **History of Pilates and Anatomy** may remain **pre-recorded**, provided a quiz supports the learning outcome - **Observation, practice teaching and self-practice** may be live-virtual, under school-approved supervision There’s a **six-month grace period.** Graduates of programs that don’t yet meet the new standard have six months from the effective date to apply. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## The three delivery formats, in plain terms This is where most of the confusion sits, because the terms sound similar and aren’t. **In person** means teacher and student in the same physical room. Bodies present, hands available. From 2027 this is required for at least part of Repertoire and Special Populations, the pieces where a teacher needs to see and correct movement. **Live virtual** means real time over video. Teacher and student together in time but not in space. Still permitted for observation, practice teaching and self-practice, provided your school supervises it. **Pre-recorded** means content the student works through at their own pace. No teacher present. Permitted for History of Pilates and Anatomy, and only when **a quiz supports the learning outcome.** The assessment isn’t a nice-to-have; it’s the condition attached to the permission. Read that way, the logic is straightforward. Anything requiring a teacher’s eye on a moving body has to be live. Anything that’s knowledge acquisition, and can be tested, doesn’t. ## Why anatomy is treated differently Anatomy is the one block in a Pilates curriculum that doesn’t need hands on bodies. Origins, insertions, actions, how muscles produce and control movement. That’s information a trainee has to *know*, and knowing it is testable. There’s no equivalent of a correction. Nobody needs to adjust your understanding of where the psoas attaches; you either have it or you don’t, and a quiz will tell you which. Repertoire is the opposite. You can watch a video of a footwork series a hundred times and still do it wrong, because the thing being taught is what it feels like and what a teacher sees when it isn’t right. The standard, in other words, isn’t arbitrary. It’s drawing a line between things that require presence and things that don’t. ## The timing is closer than the date suggests Here’s the part programs miss. A comprehensive Pilates training runs **9 to 18 months** part-time. Which means **any cohort you enroll from here graduates under the new standards.** Not the ones you enroll in December 2026. The ones you’re enrolling now. So the curriculum decision has to be settled before your next cohort starts, not before January. If you’re auditing your curriculum against the new rules, and a lot of programs are, anatomy is the piece you’re specifically permitted to hand off. ## What about students already mid-program? The six-month grace period exists for exactly this. Graduates of programs that don’t meet the new standard have six months from January 1, 2027 to apply for certification. That’s a window, not an exemption. If you have a cohort finishing in early 2027 under your current structure, they can still sit the exam, but the cohort after that can’t, unless your program has changed by then. Worth confirming your specific situation with NPCP rather than relying on a general reading of the rule. That’s what they’re there for. ## What this doesn’t change **The total hours haven’t moved.** Comprehensive is still 450, covering Mat, Reformer, Trapeze Table, Wunda Chair, Ladder Barrel, Spine Corrector and Magic Circle. **NPCP still credentials individual teachers, not programs.** Passing the NCPT is your graduate’s achievement, not your program’s accreditation. If you want your *program* independently reviewed, that’s the PMA’s ITTAP, a separate organization running a separate process. [We’ve written about how the two differ.](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/pilates-accreditation-bodies-compared/) **And nothing here says you have to** [**outsource**](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/teach-anatomy-yourself-or-outsource/) **anything.** You can teach anatomy live and in person if you want to. The standard says you *may* pre-record it. It’s permission, not instruction. ## Questions programs are asking ### **Does a textbook count as pre-recorded content?** The requirement specifies a quiz supporting the learning outcome. A book alone doesn’t include one, so you’d need to build and administer assessment separately. ### **Do we need to keep quiz results?** Certification requires your program to verify a candidate’s education, and NPCP audits that verification. Keeping per-student records is the practical way to be ready for that. ### **Can our anatomy be live and still meet the standard?** Yes. Live exceeds the requirement. Pre-recorded is the option, not the obligation. ### **What if we use an outside anatomy course?** That’s permitted. What matters is the format and the assessment, not who produced it. No anatomy course is “NPCP-approved,” because NPCP doesn’t approve curriculum providers. But a course can match the format the standard permits. ## Read it yourself Don’t take our word for any of this. The requirements are public: - [NPCP Comprehensive Eligibility Requirements](https://nationalpilatescertificationprogram.org/NPCP/NPCP/Get_Certified/Requirements.aspx) - [NPCP Mat Eligibility Requirements](https://nationalpilatescertificationprogram.org/NPCPMAT/NPCPMAT/Get_Certified/Requirements.aspx) Standards change, and this one changes on a specific date. Confirm the current version with NPCP before making curriculum decisions. **Handling the anatomy piece.** We build pre-recorded, self-paced anatomy for Pilates teacher training: 12 modules, 79 lessons, 15 hours, with a quiz at the end of every module. [Anatomy for your Pilates teacher trainings →](https://3dmusclelab.com/anatomy-for-pilates-teacher-training/) The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/whats-your-learning-style/ Author: David Keil · Updated: 2025-12-17 How We Learn # We have different ways of learning ![What's Your Learning Style?](https://3dmusclelab.com/wp-content/uploads/2018/05/learning-style.jpg) Have you ever noticed, when learning a new skill, that you pick it up easily in some contexts, but it’s more challenging to retain new information in others? We all learn a little differently. Educators refer to these differences as “learning styles”. Learning is most efficient when we set up the contexts that support our learning style, i.e. our own individual style of taking in new information. ## How do educators distinguish between learning styles? Educators describe learning styles in a couple different ways. The first model they use to describe styles of learning distinguishes between the senses we use most prominently when taking in new information. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Model one: Sense-led We might learn predominantly by: - hearing new information (auditory) - seeing new information (visual) - doing something with our body to take in new information (kinesthetic) Some educators also include taking in new information through reading and writing as its own style. This way of distinguishing learning styles is familiar to many people. You might already recognize that you learn more easily if you watch someone show you how to do a new task (visual learner), or it might be enough for you if someone simply describes it verbally (auditory learner). For others, they might understand a new task most readily if they do the task themselves, while possibly having someone talk them through the process (kinesthetic learner). Finally, others may learn readily by reading about how to do a new task. Of course, it’s likely that while you may predominantly favor one style of learning, some combination of these best supports your learning process. ## Model two: Process-led The second model that educators use to describe learning styles is by describing how we predominantly process new information. We might process new information: - more actively or more reflectively - more sensing or more intuitively - more visually or more verbally - more sequentially or more globally This second way of distinguishing learning styles may be less familiar to you, so let’s explore these a little further. Active learning vs. reflective learning: Do you readily integrate new information as you’re actively doing a new task, or do you need time to reflect on the task outside of the activity to understand more fully? Sensory learning vs. intuitive learning: Do you find that you understand new information best when you focus on discrete facts or when you focus on the broader meaning of the information? Visual learning vs. verbal learning: Do you integrate new information more easily by seeing it or by hearing, reading, or talking about it? Sequential learning vs. global learning: Do you understand a new task more fully if you approach it step by step in a linear fashion, or do you grasp new tasks best when you are presented with a big picture look at the task before diving into each step? ## What does this mean for me? You might retain information more easily when you take it in, in one way as opposed to another. Or you may feel you learn best when you take in information in some combination of these ways. The important thing is that you get to know yourself and what works for you. Experiment with learning the information in different ways. Watch. Read. Listen. Do an activity. Is there one way that feels easier to you or one way that you struggle with? Do you retain information better when you hear it out loud or when you read it as text? Does note-taking help you retain what you hear or see? Or do you find it distracts you? Similarly, take note of how you prefer to process information. Are you more sequential or global? Do you like to start at the beginning and go step by step or do you like to preview the whole project and get a “big picture” idea of where everything is going before you dive in? Do you process information more actively as you’re doing an activity, or do you need time to reflect on what you’ve learned to integrate new information? There are lots of different [ways in which we learn](https://3dmusclelab.com/how-we-learn/). Learning more efficiently depends on you! Think back to the last new skill you learned or the last course you took. What worked for you and what didn’t? What channels did you use to take in the information and how did you process it? Use what you know about your own learning styles to intentionally set the context for efficient learning. ## Learning styles and the 3D Muscle Lab course Each lesson in the [3D Muscle Lab course](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) gives you the opportunity to listen to and watch the lesson, read the assignment, do an activity and take a quiz related to the information – so you can learn in a way that works for you! The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/whiplash/ Author: David Keil · Updated: 2025-12-17 Injuries # An Anatomical Exploration Of Whiplash ![Whiplash Anatomy](https://3dmusclelab.com/wp-content/uploads/2025/11/whiplash-injury.jpg) Whiplash injury is so common that we all probably know someone who has experienced it or have experienced it ourselves. But despite how commonly it occurs, doctors and researchers are still puzzling over exactly what happens anatomically and biomechanically during this situation. In this article, I share what research has found about what happens during whiplash and which structures and tissues in the body are most often impacted. ## What Is Whiplash? Whiplash is caused by a sudden impact that forces the head, cervical spine, and torso through a series of movements outside of what our bodies can physiologically tolerate. Specifically, the pelvis and torso are thrown rapidly forward, the head is thrown backward relative to the torso and shoulders, then forward again. This action takes the regions of the cervical spine into abrupt, strong hyperextension, then back into [flexion](https://3dmusclelab.com/anatomical-terms-for-movements/). There is a moment during which the cervical spine is thrown into an S-shape created by hyperextension of the lower cervical vertebrae and flexion of the upper cervical vertebrae. The quick back and forth “whipping” series of actions, as well as the movement of the vertebrae beyond what we can physiologically support, creates compression and shear forces on the cervical spine. The specific position of our body, especially our head and neck, at the moment of impact, can influence the specific injuries we experience. ### When does whiplash occur? Whiplash most often happens in automobile collisions, either from behind or from the side. However, it can also happen in other acute accidents like contact sports when there is sufficient abrupt force from behind, as in a collision between two players in football or rugby. It has also been reported from other activities where a similar force is present, like a fall from a horse, a diving accident, or a skiing accident. In order to study this complex set of actions and resulting injuries, researchers have conducted simulations using both computer modeling and crash test dummies, examined human cadavers, and conducted animal testing. However, the complexity of each individual situation and of modeling the human body in that situation have made studying this situation difficult. For that reason, researchers are still identifying exactly what happens during a whiplash situation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What kind of injuries are experienced after whiplash? Many different structures in our body can be involved in the injury, depending on the amount of force during the collision and the position of the person. Specific symptoms and injuries are extremely varied, from mild injuries that heal on their own in a few weeks to significant injuries that linger with chronic injury-associated issues. Stiffness and sensations after a whiplash generally center around the neck. However, depending on the severity of the impact and the position of the person, other structures in the body may also be affected. ### Structures and tissues affected could include: - Muscles, especially the [sternocleidomastoid, splenius capitis](https://3dmusclelab.com/neck-muscles-superficial/), [semispinalis capitis](https://3dmusclelab.com/the-deep-neck-muscles/), and upper trapezius muscles - Spinal [ligaments](https://3dmusclelab.com/ligaments-and-tendons/), especially the anterior longitudinal ligament - Cervical vertebrae, especially the facet joints, facet capsular ligaments, and the [intervertebral discs](https://3dmusclelab.com/herniated-bulging-and-ruptured-vertebral-discs/) - Thoracic [vertebrae](https://3dmusclelab.com/exploring-the-spine/) - [Ribs](https://3dmusclelab.com/ribcage/) and [shoulders](https://3dmusclelab.com/shoulder-joint-in-movement/) - Vertebral artery - [Nerves and nerve roots](https://3dmusclelab.com/brachial-plexus/), especially the dorsal root ganglia - In more severe cases, whiplash injuries can include [bone fractures](https://3dmusclelab.com/bone-breaks-fractures-and-heals/) - Other tissues and structures specific to injury circumstances ### Symptoms Like the specific structures and tissues affected by whiplash, the symptoms are variable depending on the specific situation. Variables like how much force was present at impact, the position of the person at impact, and the existing health of the person influence the body of symptoms that they may experience. Common symptoms include: - Pain and stiffness of affected structures, particularly the neck, but can extend to other areas of the spine and back - Altered muscle recruitment in the neck and other affected structures - Dizziness - Numbness in [arm/hand](https://3dmusclelab.com/hand-and-wrist-anatomy/) - Headache - Vision issues - Mental focus difficulties, memory, concentration issues, etc. The potentially traumatic nature of a whiplash experience can also result in changes to the central nervous system, including hypersensitivity to pain and other stimuli, and psychological distress. ## Dealing with whiplash Whiplash treatment is usually divided into acute and chronic types. Individuals may recover from acute, short-term symptoms within 2-3 weeks after impact. However, many individuals also experience chronic symptoms after a collision or impact that caused whiplash. Because the specific types of injuries are extremely variable, treatments are as well. Additionally, diagnosing what structures and tissues are injured as a result of a whiplash is difficult. One reason it’s difficult to be certain which tissues and structures were injured is that many areas of abnormal tissue don’t show up on common types of imaging diagnostics. Additionally, it’s difficult to know which physiological cervical issues stemmed from the injury and which were pre-existing. And that also makes treatment plans difficult. A full assessment from an experienced medical professional is important for creating a treatment plan to address chronic whiplash-related symptoms. ## Conclusion Whiplash occurs when we experience a sudden impact with sufficient force to throw our head and neck into a series of hyperextension and hyperflexion movements that are more than our bodies can physiologically tolerate. The particular structures and tissues affected vary according to the specific situation. Similarly, the symptoms and treatments are variable. Consult an experienced medical professional to develop a treatment plan. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Curatolo, M., N. Bogduk, P.C. Ivancic, S.A. McLean, G.P. Siegmund, and B.A. Winkelstein. 2011. The role of tissue damage in whiplash-associated disorders: discussion paper 1. Spine 36(25 Suppl):S309-15.](https://pmc.ncbi.nlm.nih.gov/articles/PMC3248632/) [Elliott, J. M., J. T. Noteboom, T. W. Flynn, and M. Sterling. 2009. Journal of Orthopaedic & Sports Physical Therapy. 39(5):312-323.](https://www.jospt.org/doi/10.2519/jospt.2009.2826) [Siegmund, G.P. 2002. The biomechanics of whiplash injury. British Columbia Medical Journal. 44(5):243-247.](https://bcmj.org/articles/biomechanics-whiplash-injury) [Yadla, S., J.K. Ratliff, and J.S. Harrop. 2007. Whiplash: diagnosis, treatment, and associated injuries. Curr Rev Musculoskelet Med. 1(1):65–68.](https://pmc.ncbi.nlm.nih.gov/articles/PMC2684148/) --- Source: https://3dmusclelab.com/shin-splints-shin-pain/ Author: David Keil · Updated: 2025-12-17 Injuries # Are Shin Splints The Cause Of My Shin Pain? ![Shin Splints And Shin Pain](https://3dmusclelab.com/wp-content/uploads/2023/11/shin-splints.jpg) Overuse injuries are a frequent occurrence in athletes in a wide variety of sports and activities. They are also prevalent among military recruits and other work environments that require significant [walking](https://3dmusclelab.com/what-is-the-gait-cycle/) and running. Shin splints are one type of chronic overuse injury. This collection of symptoms is particularly common among runners, ballet dancers, and military recruits. In this article, let’s take a look at what this term means, and explore its symptoms and potential causes. ## Definitions There is some debate over what the common term shin splints actually means. Currently, researchers tend to use that term to refer to a description of symptoms, rather than a specific diagnosis. Even the more technical phrases “medial tibial syndrome” or “medial tibial stress syndrome” may be used to refer to more than one diagnosis. What all these terms have in common is that they refer to the experience of chronic pain at the medial border of the tibia. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Causes of medial shin pain There are many causes of pain and soreness at the medial border of the tibia. Most generally, medial tibial pain could be a symptom of: - Compartment syndromes - Tendinitis - Myositis - Stress fracture - Periostitis - Shin splints ## What are shin splints? The current consensus is that shin splints differ in etiology from other sources of medial tibial pain like stress fractures, compartment syndrome, and tendinitis. However, researchers studying this injury have not yet honed in on exactly what type of tibial pain constitutes shin splints as opposed to other dysfunctions or what its specific causes are. Two common hypotheses include excess contraction of the soleus and/or the tibialis posterior muscle. ### Anatomy The “shin” refers to the anterior portion of the [lower leg](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/). It’s usually used more specifically to refer to the anterior portion of the tibia bone. (That’s the larger of our two lower leg bones.) The tibia goes from your [knee](https://3dmusclelab.com/knee-joint/) to your [ankle](https://3dmusclelab.com/exploring-the-ankle-joint/) and forms part of each of those [joints](https://3dmusclelab.com/synovial-joint/). The pain from shin splints typically shows up along the medial border (the side closer to the inside of your leg) of the anterior side (the front) of this bone. The most superficial muscle on the back of the leg is gastrocnemius and deep to that is soleus. Underneath soleus, you can find the small tibialis posterior. These are the [muscles](https://3dmusclelab.com/muscle-origin-insertion-and-action/) that researchers have been most interested in as a potential cause of shin splints. Excess contraction of muscles on the posterior side (back) of the leg could potentially cause [reciprocal tension](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) through the front of the leg. And that, could lead to shin splint-type pain through constant irritation of these tissues, trigger point formation, and other mechanisms. ### Causes In order to differentiate between shin splints and other injuries, one study used a particular type of bone imagery. The bone imaging (radionuclide angiogram and blood pool images) showed markers associated with abnormality of the lower extremity that might be associated with shin splints. Specifically, they found abnormalities of the medial origin of soleus and its [fascia](https://3dmusclelab.com/what-is-muscle-fascia/), but not the tibialis posterior (Michael and Holder, 1985). They extrapolated the [biomechanical significance](https://3dmusclelab.com/functional-movement/) from their direct findings and hypothesized that excess contraction of soleus and pronation of the foot at the ankle could cause the effects they saw (Michael and Holder, 1985). Other more recent research supported the contributions of excess [contraction](https://3dmusclelab.com/muscle-contractions/) of soleus to shin splints. However, they also suggested contraction of tibialis posterior as a potential contributor (Wilder et al., 2004; Thacker et al., 2002). It’s also possible that there is more than one cause of this particular collection of symptoms. Shin splints are generally diagnosed during an in-person exam by a doctor and with supporting information from an X-ray and/or an MRI. ### Symptoms Symptoms of shin splints include medial tibial pain and tenderness. The pain is usually found along the middle to distal (lower) third of the tibia. And, the tenderness is especially common after exercise. There is sometimes some slight edema in the area. Additionally, the muscles in the region where people experience pain may also feel tense. ## Causes of overuse injuries, including shin splints There are a number of factors that contribute to overuse injuries generally and shin splints in particular. They include intrinsic issues within the body as well as extrinsic issues, such as approaches to training for a sport. Those causes include combinations of the following: - Muscle imbalance, inflexibility, and/or weakness in the leg, particularly overly tight and/or weak soleus and gastrocnemius - [Hyper-pronated feet](https://3dmusclelab.com/exploring-plantar-fasciitis/) - Body mass index over 30 - Muscular imbalances in the thoracolumbar area - Poor technique and/or improper equipment in a relevant sport or activity - Poor footwear - Overtraining or an increase in training too quickly ## Treatments Treatments for shin splints depend, of course, on each individual case. If you are experiencing medial shin pain, please see an appropriate medical professional for a diagnosis. Depending on the situation and the extent of the injury, treatments might consist of: - Rest - Physical therapy - Ice - Orthotics - NSAIDs - [Flexibility exercises/stretching](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/) - Surgery is usually a last resort and is variable in its effectiveness. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bates, P. 1985. Shin splints – A literature review. British Journal of Sports Medicine. 19(3):132-137.](https://pubmed.ncbi.nlm.nih.gov/3907743/) [Bhusari N. and M. Deshmukh. 2023. Shin Splint: A Review. Cureus. 15(1):e33905.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9937638/) [Michael, R.H. and L.E. Holder. 1985. The soleus syndrome: A cause of medial tibial stress (shin splints). The American Journal of Sports Medicine. 13(2):87-94.](https://pubmed.ncbi.nlm.nih.gov/3985265/) [Thacker, S.B., J. Gilchrist, D.F. Stroup, and C.D. Kimsey. 2002. The prevention of shin splints in sports: a systematic review of literature. Medicine and Science in Sports and Exercise. 34(1):32-40.](https://pubmed.ncbi.nlm.nih.gov/11782644/) [Wilder, R.P. and S. Sethi 2004. Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints. Clinics in Sports Medicine. 23:55-81.](https://pubmed.ncbi.nlm.nih.gov/15062584/) --- Source: https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/ Author: David Keil · Updated: 2025-12-17 Injuries # What Are Golfer’s Elbow And Tennis Elbow? ![Golfer's Elbow And Tennis Elbow](https://3dmusclelab.com/wp-content/uploads/2020/05/golf-tennis-elbow.jpg) The elbow joint is often associated with overuse-type injuries, two of which are commonly referred to as golfer’s elbow and tennis elbow. Both of these common names refer to what is more technically called tendinosis. You might have previously heard golfer’s elbow and tennis elbow referred to as tendinitis or epicondylitis. However, current research suggests that the more accurate description of these symptoms is actually tendinosis. ## What’s the difference between tendinosis and tendinitis? Tendinosis means a deterioration of the collagen fibers in the tendon as a result of overuse. Overuse injuries like golfer’s elbow or tennis elbow occur when an action is repeated over time. This is in contrast to an acute type of injury, which might be the result of a fall or an accident. Tendinitis refers to inflammation of a tendon that would occur from micro-tears often as a result of that kind of acute injury. It’s important to distinguish between these two terms because the treatment for each of these two situations can be very different. Golfer’s elbow and tennis elbow are technically called medial epicondylosis and lateral epicondylosis. The epicondyles are rounded bony protuberances at the distal end of the humerus. They are attachment sites for multiple muscles and tendons. The medial epicondyle is located on the inside of the elbow and the lateral epicondyle is on the outside of the elbow. Medial epicondylosis means that this degeneration is happening at the tendon which attaches to the medial epicondyle of the humerus. It’s commonly called golfer’s elbow due to the specific repetitive use actions that occur in that sport. Lateral epicondylosis specifically refers to degeneration of the attachment of the common extensor tendon at the lateral epicondyle of the humerus. It’s commonly called tennis elbow due to the actions repeated in that sport. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Why might lateral epicondylosis occur in tennis players? The common extensor tendon on the lateral epicondyle is where a number of forearm and wrist muscles meet to form that common tendon. Those muscles are generally responsible for [extension of the wrist](https://3dmusclelab.com/hand-and-wrist-anatomy/) and supination of the forearm. This combination of wrist and forearm movements is repeated frequently in tennis racket strokes, particularly in the backhand stroke. ## Lateral epicondylosis is not unique to tennis players Other activities that repeat the same actions could cause the same irritation and deterioration of the common extensor tendon attachment over time. Any kind of activity that requires repetitive wrist extension can lead to tendinosis of the extensor tendons (not just tennis). Other activities where lateral epicondylosis could occur include: other racket sports, like racquetball or squash, fencing, and occupations such as meat cutting, plumbing, or painting. ## Why might medial epicondylosis occur in golfers? The specific combination of elbow and forearm movements used in a golf swing can irritate the tendinous attachment of the forearm muscles at the medial epicondyle of the elbow and eventually result in some degeneration of the collagen fibers at those tendinous attachments. In this case it is specifically tendinosis of the tendinous origin of the flexors and pronator muscles which attach to the medial epicondyle of the humerus. Activities that require repetitive wrist flexion and or forearm pronation, like golf swings, can lead to tendinosis of the flexor and pronator tendons. When this is repeated frequently over time, this can result in medial epicondylosis. ## Medial epicondylosis is not unique to golfers Other occupational tasks like repetitively using tools (screwdriver, hammer, etc.), bricklaying, typing, or painting can also contribute to tendinosis of the medial epicondyle. You might also see golfer’s elbow come up in other sports such as rowing or pitching in baseball. Golfer’s elbow is a little less common than tennis elbow, but still occurs frequently among elbow and forearm overuse injuries. ## Symptoms of golfer’s elbow and tennis elbow Symptoms of either lateral or medial epicondylitis tend to show up in the dominant arm and are about equally as common among women as in men (Jobe and Ciccotti, 1994). Symptoms of lateral epicondylosis might specifically include pain on or around the lateral epicondyle which can radiate into the forearm. Symptoms of medial epicondylosis might include pain that is on or around the medial epicondyle. The pain is often worse when a person resists wrist flexion or forearm pronation. If you experience symptoms of either tennis elbow or golfer’s elbow, see an appropriate medical professional for a thorough assessment and treatment plan. If you’d like to learn more about structures that make up the elbow joint and forearm, check out the article [Exploring The Elbow Joint And Forearm](https://3dmusclelab.com/elbow-joint-and-forearm/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Bass, E. 2012. Tendinopathy: Why the difference between tendinitis and tendinosis matters. International Journal of Therapeutic Massage Bodywork. 5(1):14-17.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3312643/) [Jobe, F.W. and M.G. Ciccotti. 1994. Lateral and medial epicondylitis of the elbow. Journal of the American Academy of Orthopaedic Surgeons. 2(1):1-8.](https://www.ncbi.nlm.nih.gov/pubmed/10708988) [McMurtrie, A. and A.C. Watts. 2012. Tennis elbow and golfer’s elbow. Orthopaedics and Trauma. 26(5):337-344.](https://www.orthopaedicsandtraumajournal.co.uk/article/S1877-1327(12)00119-4/abstract) [Sellards, R. and C. Kuebrich. 2005. The elbow: Diagnosis and treatment of common injuries. Primary Care: Clinics in Office Practice – Journal. 32:1-16.](https://www.ncbi.nlm.nih.gov/pubmed/15831310) --- Source: https://3dmusclelab.com/exploring-plantar-fasciitis/ Author: David Keil · Updated: 2025-12-17 Injuries # Exploring Plantar Fasciitis ![Plantar Fasciitis](https://3dmusclelab.com/wp-content/uploads/2022/10/plantar-fasciitis.jpg) We don’t often think about how important the bottom of our feet are. That is, we don’t think about it until we experience pain or dysfunction. Then we realize just how important healthy [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/) is everywhere, including on the bottom of our feet. We need that tissue to be healthy and responsive in order to stand, walk, run, and do all kinds of daily tasks. When our feet aren’t able to support us, it can be very disruptive to all the things we need to do during the day. In this article, we’ll take a look at plantar fasciitis, one very common condition of the connective tissue on the bottom of our feet. ## What is the plantar fascia? Plantar fasciitis occurs in the plantar [fascia](https://3dmusclelab.com/what-is-muscle-fascia/), which is a sheet of connective tissue on the bottom of our foot. It attaches near the middle of the heel, then continues along the bottom of our foot to attach at the other end to the base of our toes. The tensile strength of the plantar fascia helps maintain the medial longitudinal arch in our foot, particularly when we take a step and put a lot of force down through the foot into the ground. The plantar fascia works as a cable to tighten and then release to help absorb shock as we step. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is plantar fasciitis? Plantar fasciitis occurs when the plantar fascia on the bottom of our feet is repetitively tugged away from its attachments on the bone. This can lead to irritation of the tissue and tearing (microtears). As a result, we can experience inflammation and eventually degeneration of the plantar fascia. ## Symptoms There may be inflammation associated with this condition. There is almost certainly pain. The typical pain pattern that most people feel is pain at the center of the heel and possibly along the rest of the sheet of plantar fascia. Most people report that the pain is the worst when they first get out of bed in the morning or when they stand up after a long period of sitting. This is common because your connective tissue cools and tightens overnight. The plantar fascia becomes our Achilles tendon when we follow it up our leg. And of course, the Achilles tendon is the [tendinous attachment](https://3dmusclelab.com/ligaments-and-tendons/) of our gastrocnemius and soleus muscles. So, anytime we shorten the calf muscles, and therefore the Achilles tendon, it will also put tension on the plantar fascia. If we’re experiencing plantar fasciitis, then any action that changes the tension of the plantar fascia may also cause pain. Lifting the toes will change the tension on the plantar fascia from the other end, and can cause pain as well. In some cases, plantar fasciitis can also be associated with bone spurs in the heel. The repetitive pulling of the plantar fascia away from its attachment on the heel bone can leave a space that our bone-building cells (osteoblasts) then fill in with more bone. Pain can come from just the pulling tension of the plantar fascia being tugged away from the attachment on the heel and/or the presence of a heel spur. Of course, plantar fasciitis is not the only condition that causes heel pain or pain along the bottom of the foot. Conditions such as stress fractures, nerve impingements, aging-related atrophy, bursitis, and problems with the ankle or [knee](https://3dmusclelab.com/knee-joint/) are among some of the other reasons for experiencing heel and foot pain. As with any symptom of pain or dysfunction in the body, it’s important to see an appropriate medical professional for a full assessment and diagnosis before seeking treatment. ## What causes this condition? The specific mechanisms that cause plantar fasciitis are unknown. Researchers have hypothesized several different types of biomechanical foot stresses that could lead to plantar fasciitis. For example, stresses on the plantar fascia can be exacerbated both by too much flexibility of the foot, especially excessive pronation. The plantar fascia can also be stressed by too much rigidity of the foot when it is not able to pronate enough to dissipate the forces going through the foot when we step onto it (Bolgla et al., 2004). The causes of the pain symptoms characterized as plantar fasciitis are still being debated among researchers. Previously plantar fasciitis has been described as inflammation of the irritated plantar fascia. Some recent research suggests that what is actually happening is degeneration of the plantar fascia and therefore it should be called plantar fasciosis (Boakye et al, 2018). What seems likely based on research is that there is more than one condition or group of conditions that can lead to the experience of plantar fasciitis symptoms. ### Risk factors Factors that increase the likelihood of developing plantar fasciitis include: - Obesity - Biomechanical imbalances (too little arch, too much arch, too much flexibility, too much muscle tension, etc.) - Long periods of standing or walking - Sports or activities that include lots of running and/or jumping - Issues with shoe-fit ## Treatments Because there are different reasons that plantar fasciitis may occur, effective treatments vary depending on the situation causing the symptoms. ### Least invasive treatments include: - Reduce inflammation (anti-inflammatory meds: e.g. NSAIDS and/or ice) - Discontinue activities that are causing the symptoms, rest, and let tissue heal - Physical therapy to rebalance foot and leg muscle tension, address postural habits, and rehabilitate gait cycle if needed - In some cases, researchers have found strengthening exercises for intrinsic foot muscles to be helpful, but research on strengthening as a treatment is currently inconclusive (Huffer et al., 2016). ### More invasive treatments: - Orthotics - Night splints - Corticosteroid injections on the plantar fascia - Extracorporeal shockwave therapy ### Most invasive treatment: - Surgery ## Conclusion While there are many reasons for heel and foot pain, one very common condition with those symptoms is plantar fasciitis. People who need to stand for long periods of time at their job and athletes who do a lot of running are particularly at risk. However, most people who experience this condition recover without needing surgery or invasive treatments. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Boakye, L., M.C. Chambers, D. Carney, A. Yan, M.V. Hogan, and S.O. Ewalefo. 2018. Management of symptomatic plantar fasciitis. Operative Techniques in Orthopaedics. 28:73-78.](https://www.sciencedirect.com/science/article/abs/pii/S1048666618300168) [Bolgla, L.A. and T.R. Malone. 2004. Plantar fasciitis and the windlass mechanism: A biomechanical link to clinical practice. Journal of Athletic Training. 39(1):77-82.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC385265/) [Huffer, D., W. Hing, R. Newton, and M. Clair. 2018. Strength training for plantar fasciitis and the intrinsic foot musculature: A systematic review. Physical Therapy in Sport. 24:44-52.](https://pubmed.ncbi.nlm.nih.gov/27692740/) [Luffy, L., J. Grosel, R. Thomas, and E. So. 2018. Plantar fasciitis: A review of treatments. Journal of the American Academy of Physician Assistants. 31(1):20-24.](https://pubmed.ncbi.nlm.nih.gov/29227320/) [Myers, T. W. 2014. Chapter 3: The Superficial Back Line. In: Anatomy Trains. (New York: Churchill Livingstone). p.79.](https://www.anatomytrains.com/product/anatomy-trains-fourth-edition/) [Ribeiro, A.P., F. Trombini-Souza, V.D. Tessutti, F.R. Lima, S.M.A. Joao, and I.C.N. Sacco. 2010. The effects of plantar fasciitis and pain on plantar pressure distribution of recreational runners. Clinical Biomechanics. 26:194-199.](https://pubmed.ncbi.nlm.nih.gov/20843589/) [Rosenbaum, A.J., J.A. DiPreta, and D. Misener. 2014. Plantar heel pain. Medical Clinics of North America 98:339-352.](https://pubmed.ncbi.nlm.nih.gov/24559879/) --- Source: https://3dmusclelab.com/the-iliopsoas-related-to-back-pain/ Author: David Keil · Updated: 2025-12-17 Injuries # What Does Iliopsoas Have To Do With Back Pain? ![Lower Back Pain](https://3dmusclelab.com/wp-content/uploads/2019/01/low-back-pain-psoas-muscle.jpg) There are many possible conditions that can lead to back pain. [Iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) issues are a potential contributing factor that can often be overlooked. In this article, we’ll explore some common ways in which the iliopsoas can contribute to back pain. Before we dig in further to examine the function of [the iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/), let’s be clear about what kind of back pain we’re talking about. The term “back pain” is very non-specific. Even “the back” can be a broadly defined area depending on who you are asking. So, if we’re talking about back pain that might have a relationship to iliopsoas, we are most likely talking about pain or discomfort felt in the low or mid-back. Anatomically, we’re looking at the sacral area, lumbar area, and the lower portion of the thoracic area. ## Where is the iliopsoas? The [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) takes a path from the twelfth thoracic vertebrae along the lumbar spine, across the joint connecting the lumbar spine to the sacrum, across the sacroiliac joint, and across the hip joint to attach onto the lesser trochanter. Because iliopsoas takes such a long path through the center of the body, it can affect what we feel through the front, the back, and the sides of the body in this area. Of course, no muscle works alone. As you might remember from our articles [What is a Muscle?](https://3dmusclelab.com/what-is-a-muscle/) and [What is Muscle Fascia?](https://3dmusclelab.com/what-is-muscle-fascia/), everything in the body is intricately interconnected. This necessary interconnection and balance is maintained by tissues in the body. When something is out of balance, we might experience pain or discomfort. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Imbalance within the iliopsoas muscle The path of iliopsoas is long, so an imbalance in tension between the top and bottom of this muscle can create feelings of shortness, discomfort, or pain in the low back or sacral area. If the upper part of iliopsoas (area from approximately T12 to L2) has excess tension, then that area of the spine would be pulled down and forward. It could be experienced as feeling locally short and tight, or it could refer pain elsewhere. Likewise, if the lower part of the iliopsoas (area from approximately L2 to L5) has excess tension, then that area of the spine would be pulled down and forward. As with tension in the upper part of the muscle, tension in the lower part could be experienced as shortness or tightness in the low back or sacrum and could refer pain. In general, the contribution of any part of iliopsoas to creating an excess anterior tilt of the pelvis has the potential to compress the lower back. ### Why might an imbalance occur between the top and bottom of iliopsoas? Everyday activities, such as sitting, can lead to chronic contraction of the iliopsoas. It’s common for us to sit a lot. We might sit for most of the day, at a desk, in a car, on the couch, etc. As the iliopsoas is the primary muscle that brings the thighs towards the torso or the torso towards the legs, we contract this muscle most of the day if we are sitting. Other contributors to imbalances of tension within the iliopsoas muscle are sports and other athletic activities, such as running and cycling. There can also be anatomical or bony differences between sides of the pelvis or conditions, such as scoliosis, that lead to shortened areas of the iliopsoas. ## Imbalance between iliopsoas and other muscles In addition to an imbalance within the muscle, there can also be an imbalance between the iliopsoas and key muscles that work with it to stabilize the pelvis. Iliopsoas has an important relationship with several other muscles. It is the relationship of tension between iliopsoas and other muscles that creates balance around the pelvis and allows for ease and efficiency in movement. If any one of these relationships is out of balance, we might experience sensation, discomfort, or pain from it. In particular, let’s take a look at the relationship between iliopsoas and piriformis and iliopsoas and the gluteal muscles. It’s important to note that iliopsoas can be out of balance with the piriformis and/or the gluteal muscles on just one side of the pelvis or both sides. This can create different postural changes and pain patterns. ### Balancing the iliopsoas and piriformis Let’s take a look specifically at the relationship between iliopsoas and the piriformis muscle. These two muscles work to maintain a balance of tension around the sacroiliac joint (SI joint). Piriformis works to pull the bottom of the sacrum and the coccyx (tailbone) towards the pubic bone. Because the path of iliopsoas takes it from the spine over the pubic bone on the way down towards the top of the femur, it puts some tension on the SI joint via the vertebrae above. This then creates the opposite action of piriformis and pulls the coccyx and bottom of the sacrum away from the pubic bone. If there is too much tension in either of these muscles, then there is potential for the SI joint to get pulled too far in either direction around its axis of rotation. Too much force from any direction that is going into the SI joint can cause discomfort and pain. ### Balancing the iliopsoas and the gluteal muscles Iliopsoas is a hip flexor and gluteus maximus is a powerful hip extensor. They work together to help maintain a balance of tension around the pelvis. If a short, contracted iliopsoas overpowers a weaker gluteus maximus on one or both sides of the pelvis, this can result in a shortened area of the low back, and potentially pain. Iliopsoas also functions to externally rotate the hip, as do gluteus minimus and gluteus medius. Strong, short, lateral gluteal muscles can exacerbate the actions of an out of balance iliopsoas and direct force into the SI joint, again, potentially creating pain. ## Trigger points and back pain Trigger points in the iliopsoas muscle are also a potential cause of discomfort and pain in the low back. Exactly what causes trigger points is still being explored by researchers, but a current hypothesis is that trigger points are points in the body where a small number of muscle cells are stuck in a state of contraction. Those points then refer sensations, including possibly pain, to other areas in the body. In the image below you can see the Xs marking common trigger points in the iliopsoas muscle and common referral pain patterns. ![Trigger Points in the Iliopsoas Muscle](https://3dmusclelab.com/wp-content/uploads/2019/01/Iliopsoas_TP.png) While the iliopsoas is one potential contributing factor to back pain, remember that sourcing back pain is complicated. If you’re experiencing back pain, make an appointment with a medical professional who can do a thorough assessment and look at the whole picture. If you’d like to learn more about the iliopsoas, you can read our article series on the [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/), including [How to Contact Your Iliopsoas](https://3dmusclelab.com/contact-your-iliopsoas-muscle/), and [Iliopsoas and Movement](https://3dmusclelab.com/iliopsoas-and-movement/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/iliotibial-band-syndrome/ Author: David Keil · Updated: 2025-12-17 Injuries # Causes And Management Of Iliotibial Band Syndrome ![Iliotibial Band Syndrome](https://3dmusclelab.com/wp-content/uploads/2020/10/it-band-syndrome.jpg) There are many types of aches, pains, and dysfunction that can show up in the legs. Many are common overuse types of injuries that often occur in those engaged with specific sports, like running or cycling. In this article we’ll take a look at one of those syndromes, iliotibial band syndrome. ## What is iliotibial band syndrome? Iliotibial band syndrome is the name given to a group of symptoms. They include pain, tenderness, and sometimes swelling, felt usually towards the distal end of the [iliotibial band](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/) (IT band) as it crosses the lateral femoral condyle, just proximal to its attachment on the tibia. Remember that the IT band is the ligamentous fascia that runs from the tensor fascia latae and gluteus maximus muscles along the lateral thigh and knee to attach to the tibia just below the knee. Researchers have suggested that greater than average ankle pronation, muscle weakness ([knee flexors, knee extenders](https://3dmusclelab.com/knee-joint/), hip abductors), differences in leg length, and slower paced cadence when running, are all associated with greater likelihood of reporting iliotibial band syndrome (Fredericson and Wolf, 2005). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What causes iliotibial band syndrome? Iliotibial band syndrome is usually considered an overuse type of injury, rather than an acute type of injury like an accident such as a fall. It often occurs when we over-train in a sport like running or cycling, ramp up in distances too quickly, or simply run or bike with a form that doesn’t work for our body structure. Most commonly, it shows up in runners (or sports that include a lot of running) and cyclists. Multiple causes for the specific pain pattern that shows up have been suggested, but all of those hypotheses are still being debated among researchers. There is no single agreed upon cause. Causes that have been suggested and that may contribute to the pain pattern experienced in iliotibial band syndrome include (Charles and Rodgers, 2020): - Friction of the IT band on the lateral femoral condyle during running, walking, or cycling - Inflammation/bursitis of the IT band bursa - Compression of the small layer of fat that acts as a cushion near the IT band distal attachment ## How is iliotibial band syndrome managed? As the causes of the pain symptoms of iliotibial band syndrome are still being debated, so are the best ways to manage this painful set of symptoms. Basic therapeutic treatments for reducing any inflammation that’s present are used first, as are a reduction or temporary elimination of sports or activities that seem to cause the pain symptoms. Following that, the most common treatments are recommended after a thorough examination by a physical therapist. Stretching and/or strengthening of muscles might be suggested depending on what your physical therapist finds during the examination. Although it’s been suggested that weakness in the abductors, such as [gluteus medius, gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/), and the [tensor fascia latae muscles](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/), contributes to iliotibial band syndrome, and that strengthening one or more of these muscles could help alleviate symptoms, it’s not clear from research whether this is true (Charles and Rodgers, 2020). A recent study of two groups of runners: one group experiencing iliotibial band syndrome and a second asymptomatic group, did not find differences in hip muscle strength between the two groups (Hamstra-Wright et al., 2020). However, researchers did find differences in the way that the two groups were using their hips and legs when running (gait patterns) (Hamstra-Wright et al., 2020). One way that symptoms of iliotibial band syndrome are sometimes managed is by having a physical therapist or sport-specific trainer make changes to your form in running or cycling to ultimately change the load pattern in the body. Addressing existing trigger points and other myofascial restrictions is also sometimes recommended to help alleviate symptoms. Only in unusually severe cases are surgical treatments used to manage iliotibial band syndrome. While there are many benefits to exercise such as running and cycling, we can also sometimes experience injuries and negative impacts. Iliotibial band syndrome is one issue that can arise in those sports in particular. As treatment is specific to each person and their situation, if you are experiencing the painful symptoms associated with this syndrome, see an experienced physical therapist for a thorough assessment. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Charles, D. and C. Rodgers. 2020. A literature review and clinical commentary on the development of iliotibial band syndrome in runners. The International Journal of Sports Physical Therapy. 15(3):460-470.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296998/) [Fredericson, M. and C. Wolf. 2005. Iliotibial band syndrome in runners: Innovations in treatment. Sports Medicine. 35(5):451-459.](https://pubmed.ncbi.nlm.nih.gov/15896092/) [Hamstra-Wright, K.L., M.W. Jones, C.A. Courtney, D. Maiguel, and R. Ferber. 2020. Effects of iliotibial band syndrome on pain sensitivity and gait kinematics in female runners: A preliminary study. Clinical Biomechanics. 76: 7pgs.](https://pubmed.ncbi.nlm.nih.gov/32388078/) --- Source: https://3dmusclelab.com/posture-and-smartphone/ Author: David Keil · Updated: 2025-12-17 Injuries # Posture And Your Smartphone ![Posture And Your Smartphone](https://3dmusclelab.com/wp-content/uploads/2022/08/posture-smartphone.jpg) In this modern world, it’s hard to get by without using a smartphone. It’s such a valuable tool! It can help us map our way to a new location, communicate when away from the computer, and even make phone calls. But how is that new device affecting your body posture? [Musculoskeletal pain](https://3dmusclelab.com/category/injuries/) didn’t originate with the mobile phone, but its use definitely hasn’t improved the amount of chronic pain people report. In this article, I’ll take a look at the effect that smartphone use has on posture and why it can sometimes lead to pain. ## What is posture? Before we get too far into discussing how your phone use can affect your structure, let’s take a step back and talk about posture generally. One broad definition of posture is the shape and arrangement of our body in gravity. Most generally, our posture is how we are positioned in space at any one point in time. But, what we often actually mean when we refer to “good posture,” in a health and wellness context is a structure that requires the least effort and minimizes stress on our body. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Posture and the smartphone So what posture do we adopt when we pick up our smartphone? We’re probably aware that we tend to let our head fall down in front of us toward our phone. But there’s more going on than that. Our body tends to make adjustments to how we hold our pelvis and torso in order to support our head falling forward. Those postural changes include things like increased thoracic kyphosis (rounded thoracic spine), increased lumbar lordosis (shortened low back area), and a forward inclination of our torso (leaning forward from the waist) (Betsch et al., 2021). But the effects don’t end there. Using our smartphone also affects how we hold our [shoulders](https://3dmusclelab.com/shoulder-joint-in-movement/) (Tapanya et al., 2021) and it affects muscles in our [forearms](https://3dmusclelab.com/elbow-and-forearm-in-movement/) and [hands](https://3dmusclelab.com/hand-and-wrist-anatomy/) (Bodin et al., 2019). What’s problematic about the changes we make in how we hold our body to accommodate holding our phone, is that we usually hold them for long periods of time and we do that regularly. One study found that mobile phone users spend on average more than 20 hours per week on their phone (Betsch et al., 2021). The more time we spend on our phone, the more likely our body adapts to that task, posturally. Remember that our body is a “form follows function” organism. When we repeatedly do an action, our body will create a musculoskeletal form to support that action. That’s true whether it’s a pattern that’s ideal for our body in the long term or not. And that leads to compensations in the body that stick around in our body even after we put that phone down. Research has reported that musculoskeletal disorders are showing up in as high as 84% of smartphone users (Tapanya et al., 2021)! Ultimately those musculoskeletal compensations can result in inefficient movement at best and at worst pain and injury. ## What areas are most affected? As I said above, smartphone use can create changes in our posture from the [pelvis](https://3dmusclelab.com/exploring-the-pelvis/) up to our head. Remember the chain of joints works as a kinematic chain. The muscles that tend to show up with pain are at the end of that chain. Those are the muscles of the [upper back](https://3dmusclelab.com/trapezius-muscle/), shoulders, and neck. And, what happens when we let our head fall forward in front of our body? It gets heavy! And, the more we angle the front of our neck by letting the head hang forward the heavier the head gets. So, neck muscles like the [upper trapezius](https://3dmusclelab.com/trapezius-computer-posture/) and the cervical [erector spinae](https://3dmusclelab.com/erector-spinae-muscles/), have to work hard to hold the head when we let it fall in front of our body rather than keep it on top of the spine. This head-down position can also functionally shorten muscles such as the scalenes and sternocleidomastoid. When these muscles are chronically short and tight they can compress the thoracic outlet. They can also cause trigger points to form. These trigger points can create problems in the upper extremity and even headaches. ## How to manage our phone use It’s unlikely that smartphone use is going away any time soon. But we can change how we use it. Research suggests a few changes to how we hold our phones to minimize postural compensations. One general recommendation is just to regularly vary the posture we adopt when using our phone. Try to avoid getting into a habit of always holding your body in the same way when you use your phone. For on-the-go use, try bringing the phone up toward your face, rather than your head down to your phone. Research suggests that flexing your shoulder joints at about a 30° angle to lift your phone results in the least unnecessary muscle activation (Tapanya et al., 2021). If you regularly use your phone in a stationary position, consider one of the phone stands that will lift up your phone to head height. That will allow you to relax your arms and shoulders as well as keep the head and neck in a more neutral position. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Tapanya, W., M. Swangnetr Neubert, R. Puntumetakul, and R. Boucaut. 2021. The effects of shoulder posture on neck and shoulder musculoskeletal loading and discomfort during smartphone usage. International Journal of Industrial Ergonomics. 85:103175.](https://www.sciencedirect.com/science/article/abs/pii/S0169814121000937?via%3Dihub) [Betsch, M., K. Kalbhen, R. Michalik, H. Schenker, M. Gatz, V. Quack, H. Siebers, M. Wild, and F. Migliorini. 2021. The influence of smartphone use on spinal posture – A laboratory study. Gait and Posture. 85:298-303.](https://pubmed.ncbi.nlm.nih.gov/33640863/) [Bodin, T., K. Berglund, and M. Forsman. 2019. Activity in neck-shoulder and lower arm muscles during computer and smartphone work. International Journal of Industrial Ergonomics. 74:102870.](https://www.sciencedirect.com/science/article/abs/pii/S0169814118303500) --- Source: https://3dmusclelab.com/rotator-cuff-muscles-shoulder-pain/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Rotator Cuff Muscles And Shoulder Pain – Why Does It Happen? ![Rotator Cuff And Shoulder Pain](https://3dmusclelab.com/wp-content/uploads/2023/08/rotator-cuff.jpg) Shoulder pain is a relatable experience for many people. And, one of the most common sources of that pain is dysfunction or injury of the rotator cuff muscles. In this article, we’ll take a look at why that muscle group is so often associated with shoulder pain. ## What and where are the rotator cuff muscles? Before we dive into shoulder pain, let’s take a moment to review this muscle group. Remember that we have four [rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles/): subscapularis, infraspinatus, teres minor, and supraspinatus. All four of these muscles attach to the [scapula](https://3dmusclelab.com/scapula/) at one end and the humeral head on the other end. The tendons of these muscles all come together and form a cuff around the humeral head which is where the group gets its name. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the actions of each of the rotator cuff muscles? Each of the rotator cuff muscles has a specific primary action. Remember that the subscapularis does medial rotation of the humerus. The supraspinatus initiates abduction of the humerus. And, infraspinatus and teres minor do lateral rotation of the humerus. However, although every anatomy book lists specific actions that these muscles do when they [concentrically contract](https://3dmusclelab.com/muscle-contractions/), one of their most important actions is actually stabilization. They work together as a group to stabilize the humeral head in the glenoid fossa from multiple directions. For example, subscapularis helps stabilize the humeral head and resists anterior translation. Infraspinatus and teres minor balance that. They stabilize the humeral head and resist posterior translation. With that in mind, we could consider that a primary [“job” of the rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles-and-movement/) is to stabilize the humeral head in the socket so that we can use our arms and hands to do fine motor movements. Each of the four muscles on its own is a relatively small muscle. They act as synergists alongside more powerful prime movers rather than initiating big movements themselves. ## Why are healthy rotator cuff muscles so important? The socket (called the glenoid fossa) where the head of the humerus inserts to form the shoulder joint, is shallow. It takes muscles, ligaments, and tendons all under the right balance of tension to hold the head of the humerus in the socket and keep the joint functional. Any injury or strain in one muscle of the rotator cuff will affect the stability and balance of the whole shoulder joint. ## Why are the rotator cuff muscles so often a cause of shoulder pain? ### Overuse Many sources note that rotator cuff tendonitis is the most common cause of shoulder pain. But why is that? There are a few reasons. One simple reason is overuse. We do a lot of activities at work, at home, and for leisure that use our shoulders in repetitive ways. Remember that the whole [shoulder complex](https://3dmusclelab.com/shoulder-girdle/), including the shoulder joint specifically, is very mobile. This allows us to do all kinds of things including specific fine movements with our [hands](https://3dmusclelab.com/hand-and-wrist-anatomy/) and [arms](https://3dmusclelab.com/elbow-joint-and-forearm/). But, it also makes it easy to overdo it when we use these muscles. Repetitive use can lead to inflammation, irritation, or injury of these muscles. ### Imbalance Repetitive motions from work activities or sports can also cause an imbalance in the tension held between the different rotator cuff muscles. And, another very common cause of shoulder pain is an imbalance of tension between the those muscles. That can put strain on the shoulder joint and result in [pinched nerves](https://3dmusclelab.com/brachial-plexus/), pressure on a bursa, or just generally irritated [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Muscles don’t work in isolation, so an imbalance between other [agonist and antagonist muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) can also result in an imbalance in the tension of the rotator cuff muscles. Additionally, the position of the shoulder is related to the position and tension of structures in the larger kinetic chain. So, the location of the torso, ribcage, [spine](https://3dmusclelab.com/exploring-the-spine/), etc. also influences the position of the shoulder joint, and indirectly they influence the tension in the rotator cuff muscles. ### Using a small muscle for a big job Using the rotator cuff muscles for actions they’re not well-suited for can also result in shoulder pain and injury. The classic case is suddenly lifting a heavy suitcase and tearing supraspinatus. In fact, supraspinatus is the most common muscle of the rotator cuff group to get injured. It’s sometimes even referred to as the “suitcase muscle.” This is because of its association with getting irritated when we suddenly pick up a heavy suitcase and ask this muscle to do more work than it’s cut out for. However, any and all of the four rotator cuff muscles and their associated tendons can get injured if we use these muscles for big actions that they’re not well-placed or sufficiently large to handle. ### Other causes Acute trauma to either soft tissue or the bones of the shoulder can of course also cause injury to one or more of the rotator cuff muscles and cause shoulder pain. And age-related wear and tear of this muscle group can contribute to shoulder pain as well. Finally, the genetics that inform how everything comes together at your shoulder joint can affect the likelihood of experiencing rotator cuff-related shoulder pain. For instance, you may have less space below the acromion potentially creating a higher likelihood of compression, bursitis, fraying of the supraspinatus tendon, and even bone spurs. ## Types of rotator cuff-related shoulder injury and dysfunction Depending on the location and cause of the rotator cuff issue, there are different types of injuries and dysfunction that can result. The specific diagnosis of each of these dysfunctions should be handled by a medical professional and is far beyond the scope of this article. Generally, issues with these muscles could include: - Rotator cuff tendonitis - Partial thickness tear - Full thickness tear - Subacromial impingement syndrome - External impingement syndrome - Others ## Symptoms of rotator cuff-related pain Rotator cuff-related shoulder pain might show up as: - General shoulder aches and pain - Pain when doing repetitive tasks with the shoulders - Shoulder pain while lying on the shoulder when sleeping - Shoulder muscle weakness or weakness when [moving the shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/) - Additionally, there are many orthopedic tests for specific rotator cuff muscle dysfunction that are beyond the scope of this article ## Treatments for rotator cuff-related shoulder pain Treatments depend on each specific situation. If you have shoulder pain or suspect rotator cuff issues, you should consult with an appropriate medical professional for an assessment. Initial treatments for mild tendonitis might involve taking a break from activities that overuse your shoulders in a particular way. Ice and rest can often help reduce inflammation. If the issue is caused by a muscular imbalance, then an experienced physical therapist or bodyworker may be able to help. Appropriate stretching and strengthening exercises are often suggested to address the underlying causes behind mild tendonitis or small tears. In the case of more significant tears or acute trauma to the rotator cuff, surgery might be necessary. ## Conclusion There are many reasons why we might strain or injure a rotator cuff muscle. That makes this area one of the most common sources of shoulder pain. The balance of tension between these four muscles is important for maintaining a full range of motion of the shoulder. If one rotator cuff muscle is injured, it affects the kinematics of the whole shoulder. So there are also lots of good reasons for giving this area some extra care in order to maintain a healthy rotator cuff. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Horsley, I. 2005. Assessment of shoulders with pain of a non-traumatic origin. Physical Therapy in Sport. 6:6-14.](https://www.sciencedirect.com/science/article/abs/pii/S1466853X04001245) [Kolk, A., J.F. Henseler, P. Bas de Witte, E.W. van Zwet, P. van der Zwaal, C.P.J. Visser, J. Nagels, R.G.H.H. Nelissen, J.H. de Groot. 2017. The effect of a rotator cuff tear and its size on three-dimensional shoulder motion. Clinical Biomechanics. 45:43-51.](https://pubmed.ncbi.nlm.nih.gov/28477525/) [Malcarney, H.L. G.A.C. and Murrell. 2003. The rotator cuff: Biological adaptations to its environment. Sports Medicine. 33(13):993-1002.](https://pubmed.ncbi.nlm.nih.gov/14606926/) [Rathi, S., N.F. Taylor, B. Soo., and R.A. Green. 2018. Glenohumeral joint translation and muscle activity in patients with symptomatic rotator cuff pathology: An ultrasonographic and electromyographic study with age-matched controls. Journal of Science and Medicine in Sport. 21:885-889.](https://pubmed.ncbi.nlm.nih.gov/29525201/) [Varacallo M., Y. El Bitar, S.D. Mair. 2023. Rotator Cuff Tendonitis. [Updated 2023 Aug 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532270/](https://www.ncbi.nlm.nih.gov/books/NBK532270/) --- Source: https://3dmusclelab.com/trapezius-computer-posture/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Why Does My Neck Hurt When Sitting At The Computer? ![Trapezius Muscle During Computer Posture](https://3dmusclelab.com/wp-content/uploads/2020/01/desk-posture.jpg) These days, just about everyone spends some time at the computer each day. Along with all that time in front of the computer we might experience the seemingly ubiquitous tension on the back of the neck and shoulders. One culprit which can contribute to that tension and neck pain is the upper portion of the [trapezius muscle](https://3dmusclelab.com/trapezius-muscle/) (Amin et al., 2018; Ghaderi et al., 2019; Kelson et al., 2019). ## Where is the upper trapezius? Remember that [the trapezius](https://3dmusclelab.com/trapezius-muscle/) can, in a way, be considered to be three different muscles because it has three main sections which each have fibers running in a different direction from the other sections. It’s the upper portion of this muscle that we are most interested in here. This muscle attaches from the nuchal ligament, base of the occiput, and spinous processes of vertebrae C1-C7 to the lateral third of the clavicle and the acromion process. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What does the upper trapezius do? The upper trapezius can upwardly rotate and [elevate the scapula](https://3dmusclelab.com/scapula/). While the attachments at the nuchal ligament, occiput and cervical vertebrae are usually considered the origin, remember that muscle origin and insertion are simply a convenient way to organize what we know about a muscle’s attachments. Muscles can create movement in either direction depending on the circumstances. If we keep in mind the attachments of the upper portion of this muscle, then we could imagine that it could also contribute to extension of the head and neck. ## How are the upper traps involved in our computer posture? Let’s think for a moment about what movements the upper trapezius is contributing to when we sit at a computer. In this case, it’s the extension of the head and neck that it contributes to which is particularly relevant. When we sit at a computer, the upper portions of this muscle can shorten the back of the neck which shortens the distance between the head and the scapulae. In the case of sitting at a computer, we typically take our head forward and the upper trapezius has to resist that position by pulling the head back and shortening. Essentially, it’s regularly stabilizing the head and neck in a forward head position. Researchers have found that the upper [trapezius](https://3dmusclelab.com/trapezius-muscle/) is highly active when holding our shoulders, head, and neck in a posture typical of sitting at the computer (Bodin et al., 2019). The activity level of this muscle when sitting at a computer was even higher than when using a smartphone (Bodin et al., 2019). EMG studies also show that it is active when flexing and abducting the arm (Travel and Simons, 1993) as we might be doing when using a mouse at the computer. The chronic shortening and over-use of the upper trapezius in this way can potentially contribute to neck pain (Amin et al., 2018; Ghaderi et al., 2019; Kelson et al., 2019) and trigger points (Travel and Simons, 1993). In fact, Travel and Simons, 1993, note that the this muscle is the most common muscle in the body to present with active trigger points, which can refer pain to the neck and even the jaw. ## What to do at the computer? One research team found that eccentric exercises for the upper trapezius reduced neck pain (Heredia-Rizo et al., 2019), however, the most common recommendation from those who specialize in ergonomics and workplace health is simply to get up and move. Get up from the computer and change your posture frequently, at least every hour (Keown et al., 2018) and even as much as every 20 minutes (Amin et al., 2018). If you spend regular time in front of the computer, do your trapezius a favor — get up frequently, move around, and stretch to reduce neck pain. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Amin, I., A. Arshad, A. Rabia. 2018. An observational research to assess the onset of neck pain among various computer users working for various time durations on different types of computers. Indo American Journal of Pharmaceutical Sciences. 5(12):13956-13961.](http://www.iajps.com/pdf/december2018/68.IAJPS68122018.pdf) [Bodin, T., K. Berglund, M. Forsman. 2019. Activity in neck-shoulder and lower arm muscles during computer and smartphone work. International Journal of Industrial Ergonomics. 74:102870.](https://www.sciencedirect.com/science/article/abs/pii/S0169814118303500?dgcid=rss_sd_all) [Ghaderi, F., K. Javanshir, M. Asghari Jafarabadi, A. Nodehi Moghadam, and A. Masoud Arab. 2019. Chronic neck pain and muscle activation characteristics of the shoulder complex. Journal of Bodywork and Movement Therapies. 23:913-917.](https://www.ncbi.nlm.nih.gov/pubmed/31733782) [Heredia-Rizo, A.M., Petersen, K.K., Pascal, M., Arendt-Nielsen, L. 2019. Clinical outcomes and central pain mechanisms are improved after upper trapezius eccentric training in female computer users with chronic neck/shoulder pain. The Clinical Journal of Pain. 35(1):65-76.](https://www.ncbi.nlm.nih.gov/pubmed/30222615) [Kelson, D.M., S.E. Mathiassen, D. Srinivasan. 2019. Trapezius muscle activity variation during computer work performed by individuals with and without neck-shoulder pain. Applied Ergonomics. 81:102908.](https://www.ncbi.nlm.nih.gov/pubmed/31422258) [Keown, G.A., M. Chiro, and P.A. Tuchin. 2019. Workplace factors associated with neck pain experienced by computer users: A systematic review. Journal of Manipulative and Physiological Therapeutics. 41(6):508-529.](https://www.ncbi.nlm.nih.gov/pubmed/30025880) Travell, J.G. and D.G. Simons. 1993. Trapezius Muscle. *In* Myofascial Pain and Dysfunction —The Trigger Point Manual. Volume 1. --- Source: https://3dmusclelab.com/valgus-and-varus-knee-pain/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Valgus And Varus Knee Patterns And Knee Pain ![Valgus And Varus Knee Patterns](https://3dmusclelab.com/wp-content/uploads/2023/01/valgus-vargus.jpg) Knee pain is complex, varied, and has many sources. Causes range from acute trauma, like broken bones, to chronic aches and pains with no obvious source. One potential contribution to knee pain can simply be our postural patterns. In this article, let’s take a closer look at a particular knee-related aspect of our posture that can sometimes lead to knee pain: valgus and varus knees. ## What are valgus and varus patterns? A valgus knee pattern is what is colloquially sometimes called “knock-knees.” In this case, the angle between the tibia and the femur on the lateral side is smaller than it should be ideally and that angle is wider on the medial side than the ideal. In contrast, a varus knee pattern, colloquially called “bow legs,” is the opposite. The angle between the tibia and the femur is reduced on the medial side and greater on the lateral side than what is considered neutral. To simplify the naming of these patterns, Tom Myers of Anatomy Trains and others refer to the valgus knee pattern as an X-leg pattern and the varus knee structure as an O-leg pattern. Either of these patterns might be mild, with small variations in angle size in relation to what is considered neutral. In that case, the person might not experience any reduced function or pain. At the other end of the spectrum, these patterns can show up in more extreme variations. More extreme versions of these patterns can negatively affect function and sometimes cause pain. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What drives these knee patterns? The source of these patterns is complex. It may be congenital, the result of disease complications, the result of acute trauma like a broken bone, or other reasons. And, these postural patterns don’t exist in isolation, of course. They’re in the middle of the whole lower kinetic chain between the pelvis and the feet and ankles. For that reason, tension above or below can influence knee position. And, the reverse is also true. These patterns affect the way tension is held at joints above and below the knee. So both acute trauma, as well as patterns from chronic use acquired elsewhere in the body, can contribute to valgus or varus knee position. ## Do you have a valgus or varus knee position? Let’s do a little experiment to learn about your own posture. Stand in front of a mirror where you can see your knees. Slowly scoot your feet together. Notice which touches first, your feet or the insides of your knees. When you bring your feet together, do the insides of your knees meet first? Then, you have a valgus, or X-leg pattern. Do your feet meet first and do you also have significant space between your knees when your feet are together? Then you have a varus, or O-leg pattern. If your feet and the insides of your knees meet at about the same time, then your knee pattern is neutral with respect to an X-leg or O-leg pattern. ## How are these patterns related to knee pain? [The knee](https://3dmusclelab.com/knee-joint/) is primarily a hinge joint. That is, it flexes and extends easily in the frontal plane. On both the medial and lateral sides of the knee are [ligaments](https://3dmusclelab.com/ligaments-and-tendons/) holding the knee in place and resisting any pressure too far in either direction. On the medial side is the medial collateral ligament. And, on the lateral side is the lateral collateral ligament. You could imagine then that if we chronically put pressure on either of these ligaments with a valgus or varus-positioned knee that those ligaments could get over-stretched and then irritated and sore after a while. Additionally, we have both a medial and lateral meniscus. Remember our menisci are semi-circular discs that help cushion the knee. They allow the femur and tibia to glide past each other during movement. If we’re chronically putting more tension on either the lateral or medial side of [our knee joint](https://3dmusclelab.com/knee-hyperextension/), then we can potentially pinch the meniscus on the side where the tibia and femur are closer together. That can also irritate the tissues in that area and cause soreness. In both the X-leg and O-leg positions, the load-bearing force is not going through the center of the knee. Instead, the line of force is more off to one side or the other. That affects where tension goes. Over time it can increase the chances of osteoarthritis due to the extra stress either on the inside or outside of the knee and potentially result in pain (Miura et al., 2009). In an X-leg position specifically, the pattern has been linked to an increased likelihood of patellofemoral pain (Gwynne and Curran, 2018; Herrington, 2014). ## Can we change knee patterns? Yes, it is possible to change these patterns, to a point. But, if we really want to change them, we have to look more holistically at the body. There may be a genetic component to the angle of the joints at the [hip](https://3dmusclelab.com/exploring-the-adductor-muscles/), knee, and ankle. Those aren’t likely to change. Our knee position may also result from something we can’t change like a disease or acute injury. But we also acquire our patterns from activities we do as well as accidents and injuries we’ve experienced. If those patterns are held in the [soft tissue](https://3dmusclelab.com/what-is-connective-tissue/) ([muscles](https://3dmusclelab.com/what-is-a-muscle/) and [fascia](https://3dmusclelab.com/what-is-muscle-fascia/)), then there is some potential to change them. We would need to consult with an appropriate medical professional like a physical therapist or experienced bodyworker for a full assessment to understand the range within which change might be possible for our pattern. ## Conclusion Valgus and varus knee positions describe the way the tibia meets the femur at the knee joint. They refer to a pattern where the knee is positioned either medial or lateral of the ideal. In this position, the knee is more vulnerable to some types of strain on tissues surrounding it, which may cause pain as well as reduced function. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Gwynne, C.R. and S.A. Curran. 2018. Two-dimensional frontal plane projection angle can identify subgroups of patellofemoral pain patients who demonstrate dynamic knee valgus. Clinical Biomechanics. 58:44-48.](https://pubmed.ncbi.nlm.nih.gov/30015205/) [Herrington, L. 2014. Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls. The Knee. 21:514-517.](https://pubmed.ncbi.nlm.nih.gov/24380805/) [Miura, H., S. Takasugi, T. Kawano, T. Manabe, Y. Iwamoto. 2009. Varus-valgus laxity correlates with pain in osteoarthritis of the knee. The Knee. 16:30-32.](https://pubmed.ncbi.nlm.nih.gov/18954990/) --- Source: https://3dmusclelab.com/herniated-bulging-and-ruptured-vertebral-discs/ Author: David Keil · Updated: 2025-12-17 Injuries # Exploring Spinal Disc Dysfunctions ![Vertebral Disc Dysfunctions](https://3dmusclelab.com/wp-content/uploads/2019/07/bulging-herniated-disc.jpg) ## What are vertebral or spinal discs? [Our spine](https://3dmusclelab.com/exploring-the-spine/) is composed of a series of rounded bones, called vertebrae, each of which has three bony projections. Two of these bony projections point out on either side of each bone laterally and the third points out to the back, posteriorly. Sandwiched between each of the bones you’ll find what is called a spinal or vertebral disc. Vertebral discs are composed of layers of cartilage, called the annulus fibrosus, which form a ring that contains a fluid, called the nucleus pulposus. The vertebral discs are held in place by connective tissue, in general, and have additional support provided anteriorly and posteriorly by thick ligaments that run along the front (anterior) and back (posterior) sides of the spine. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is the function of vertebral discs? The fluid of the nucleus pulposus that is held within the annulus fibrosus of the vertebral disc creates osmotic pressure. This pressure and the structure of the spinal disc itself create space between each of the vertebra, which protects the nerve roots of the spine from compression by the spinal bones. The arrangement of the vertebrae alternating with vertebral discs also allows for the movement of the spine. There is space between each of the vertebra created by the squashy disc, so each of the vertebra can move at these joints a small amount. When you add up the small movements at each of the vertebral joints, you have the large amount of total movement that we know as spinal movement. ## What can contribute to dysfunction of vertebral discs? - Genetic predisposition - Injuries and accidents - Postural imbalances from work or sport activities - Aging - Sedentary lifestyle and obesity - Sometimes there is no obvious cause ## Common dysfunctions of vertebral discs ### Bulging disc A bulging disc occurs when the cartilaginous disc between two vertebrae gets compressed by the bony vertebrae above and below and bulges out in one or more places. A bulging disc on its own may or may not cause pain or interfere with function. However, if the bulge is in the direction of a spinal nerve root, you could be more likely to experience pain from a bulging disc. ### Herniated disc A herniated disc is similar to a bulging disc in that an area of the vertebral disc is pushed out from between the vertebrae above and below. In the case of a herniated disc, the area of the disc that gets pushed out is weakened or damaged in some way. As with a bulging disc, if the herniation gets pushed out in a way that causes it to press on one of the spinal nerve roots, it can cause pain, tingling, numbness or other sensations indicating a dysfunction. ### Ruptured disc In the case of a ruptured disc, the cartilaginous disc actually tears all the way to the nucleus pulposus where the fluid is stored, and the fluid starts to leak out. At this point the vertebral disc starts to lose its capacity to maintain space between the vertebrae because the fluid-filled center, which creates the pressure, has been compromised. The vertebral disc in this case can also press on nerve roots, but additional types of dysfunction are also possible as the bony vertebrae are no longer maintained apart from one another. ### Degenerative disc disease Degenerative disc disease is a general term that describes the situation when normal deterioration of the vertebral structures during aging leads to a secondary cause of pain. As we age, some amount of deterioration of body structures is normal. With respect to the vertebrae, that deterioration can include drying out and thinning of the vertebral disc, cracking and small tears in the outer wall of the disc, or bone spurs on the vertebrae. All of these signs of deterioration of the vertebrae may occur without leading to pain or a particular dysfunction in the spine. It is also possible that types of vertebral deterioration can lead, secondarily, to disc dysfunctions like herniated or ruptured disc, or pain. For example, bone spurs created during the process of disc deterioration can press on spinal nerves causing pain. The sources of pain arising from types of disc deterioration are varied, however, and a specific diagnosis would require a visit to an appropriate medical professional. Treatment of disc dysfunction varies with each specific situation, so as with any experience of pain or other potential symptom of dysfunction in the body, seek out an appropriate medical professional if you have further questions about vertebral disc dysfunction. The specifics of diagnosis and treatment of vertebral disc dysfunction are beyond the scope of this article. If you’d like to read more about muscle function and dysfunction, read the related posts below. #### Related Posts The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/ankle-sprain/ Author: David Keil · Updated: 2025-12-17 Injuries # What Happens In An Ankle Sprain? ![An Ankle Sprain](https://3dmusclelab.com/wp-content/uploads/2024/12/ankle-sprain-1.jpg) Picture it. You’re walking the dog down your neighborhood street, enjoying the scenery, when your dog suddenly lunges after a squirrel darting across her path. You take an unexpected step, stumble, and your foot rolls sideways. Ouch! You’ve just sprained your [ankle](https://3dmusclelab.com/exploring-the-ankle-joint/). Now what? In this article, we’ll take a look at the anatomy of an ankle sprain. We’ll look closer at what structures actually get injured when you sprain your ankle as well as how this extremely common injury is usually treated. ## What is an ankle sprain? An ankle sprain is an injury to the [ligaments and sometimes tendons](https://3dmusclelab.com/ligaments-and-tendons/) around your ankle joint. Remember that your ankle is really two joints. It includes the tibiofibular joint where the [tibia and fibula](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) meet the talus and the subtalar joint where the talus meets the calcaneus. We have important ligaments and tendons that cross both of these [joints](https://3dmusclelab.com/synovial-joint/). Remember that ligaments are connective tissue that connects bone to bone. Tendons are [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/) that connects muscle to bone. An ankle sprain happens when you move your ankle in a way that stretches the ligaments and tendons past the point that they can spring back. In more extreme types of ankle sprains, these ligaments and tendons might even tear, either partially or completely. An ankle sprain is one of the most common musculoskeletal injuries. It makes up about a quarter of all sports-related injuries (Struijs and Kerkhoffs, 2010). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What causes an ankle sprain? Like the scene at the beginning of this article, an ankle sprain most often occurs when we trip, stumble, or fall for some reason. It might happen during a sport or athletic activity. It can also happen during a mundane moment in daily life. Less often, ankle sprains might be part of a significant trauma like a car accident. You might be more prone to ankle sprains if your ligaments have more laxity (are looser) than average or if you have biomechanical imbalances in your ankle(s) or lower body kinetic chain. ## Anatomy of an ankle sprain There are two types of ankle sprains, low ankle sprains and high ankle sprains. Let’s take a look at the specific differences in these two injuries. ### Low ankle sprains Low ankle sprains are the more common type. More specifically, these are sprains of the lower ligaments and sometimes tendons around the ankle. It’s usually the ligaments on the lateral side of the ankle that get overstretched or torn. The most common direction of an ankle sprain is a low ankle sprain where our foot moves too much, too quickly in the inversion direction, usually when our foot is also pronated. In this situation, the ligament that is most commonly overstretched or torn is the anterior talofibular ligament which [attaches to](https://3dmusclelab.com/muscle-origin-insertion-and-action/) the lateral malleolus (the bony lower portion of your fibula) and the talus. Less commonly, you may also injure your calcaneofibular ligament in a low lateral ankle sprain. That ligament attaches to the lateral malleolus and the lateral portion of the calcaneus (your heel bone). The posterior talofibular ligament is also found on the lateral side of your ankle, but is much less commonly part of a sprain. It attaches to the lateral malleolus and the talus. While it’s possible to sprain your ankle in a way that overstretches or tears ligaments on the medial side, that’s less common. However, that kind of injury can happen when your foot pronates and the back part of your foot (hindfoot) rotates. That combination of actions will lengthen the ligaments on the medial side of your ankle. The ligaments that could be injured in that kind of sprain include: the posterior tibiotalar ligament, the tibiocalcaneal ligament, the tibionavicular ligament, and the anterior tibiotalar ligaments. It’s also possible to injure the medial deltoid ligament by spraining your ankle during an eversion movement, but this is somewhat rare. ### High ankle sprains High ankle sprains are also called syndesmosis injuries or syndesmotic ankle sprains. They are slightly different than low ankle sprains. The syndesmotic complex is a fibrous area (considered a fibrous joint) where the tibia and fibula meet at their distal (lower) ends. You have several important ligaments that help maintain stability at this connection. Those are the anterior inferior tibiofibular ligament, the interosseous ligament, the posterior inferior tibiofibular ligament, and the deep transverse ligament. In a high ankle sprain, there is damage to one or more of these upper ligaments. That can happen when we experience an injury during movement that includes external rotation of the leg and dorsiflexion of the ankle. High ankle sprains often accompany [fractures of the ankle bones](https://3dmusclelab.com/bone-breaks-fractures-and-heals/) and/or the fibula because it takes a more significant amount of force to cause an injury to this area compared to the more common low ankle sprain. The pain locations are different too. The pain in this type of injury is commonly felt between the fibula and tibia. In this type of sprain, you might feel pain when going up or down stairs, or any other time you dorsiflex your ankle. ## Symptoms Common symptoms of ankle sprains include: - Swelling - Bruising - Pain, especially when bearing weight on the injured ankle - Ankle instability - Reduced ankle mobility or range of motion in certain directions ## How is an ankle sprain diagnosed? For a very mild, brief stumble type of ankle sprain, you likely won’t need a formal diagnosis. A little ice and a few days of resting your ankle might be all you need. For a more serious ankle sprain, a doctor will conduct a physical exam. They might also do an X-ray to rule out accompanying broken bones. In a very serious sprain, they might suggest an MRI to better understand the extent of the injury and to best recommend a course of treatment. Both low and high ankle sprains are graded according to their severity. In a grade one ankle sprain, the ligaments and/or tendons are overstretched, but not torn. In a grade two sprain, the fibers of ligaments or tendons are partially torn. In a grade three sprain, there is a complete tear of ligaments or tendons at the ankle joint. ## Treatment For the most acute treatment, icing your ankle and elevating it immediately after a sprain may help reduce swelling and inflammation. You’ll likely want to avoid weight-bearing on your injured ankle for a few days to a few weeks after a sprain. How long you avoid putting weight on your ankle depends on the severity of your injury. For a very mild strain, a few days of staying off it might be enough. For a more severe injury, you should see a doctor for treatment recommendations specific to your situation. Your doctor may recommend wearing a temporary brace or using crutches to minimize weight bearing while your ankle heals. Additionally, they may recommend physical therapy exercises to stretch and strengthen the muscles around your ankle. They may also recommend manual therapy to mobilize and rebalance tissues around the ankle. For very severe injuries only, a cast may be required temporarily to stabilize the ankle or surgery could be recommended. ## Conclusion An ankle sprain is one of the most common musculoskeletal injuries. They can be caused by everything from a simple trip and fall incident in daily life to a more forceful injury during an athletic event. The specific structures injured are related to the position of the ankle and the direction of force during the injury. If you experience more than a very mild sprain, consult your doctor for an exam to determine the best course of treatment. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Struijs, P.A. and G.M. Kerkhoffs. 2010. Ankle sprain. BMJ Clin Evid. May 13;2010:1115. https://pmc.ncbi.nlm.nih.gov/articles/PMC2907605/](https://pmc.ncbi.nlm.nih.gov/articles/PMC2907605/) [Vuurberg, G., A. Hoorntje, L.M. Wink, B.F.W. van der Doelen, M.P. van den Bekerom, R. Dekker, C.N. Van Dijk, R. Krips, M.C.M. Loogman, M.L. Ridderikhof, F.F. Smithuis, S.A.S. Stufkens, E.A.L.M. Verhagen, R.A. de Bie, G.M.M.J. Kerkhoffs. 2018. Diagnosis, treatment and prevention of ankle sprains: update of an evidence-based clinical guideline. British Journal of Sports Medicine. 2018. Vol. 52:956. 15pgs.](https://pubmed.ncbi.nlm.nih.gov/29514819/) --- Source: https://3dmusclelab.com/bone-breaks-fractures-and-heals/ Author: David Keil · Updated: 2025-12-17 Injuries # What Happens When A Bone Breaks (Fractures) And Heals? ![Bone Breaks And Heals](https://3dmusclelab.com/wp-content/uploads/2024/02/bone-break-fracture.jpg) We might think of bones as being dry, rigid structures. But actually, bones, like all the other tissues in our body are dynamic living things. They are part of our body’s unique structure which has to bridge our needs for both stability and mobility. Our bones are highly adaptable and their structure reflects the individual stresses that we put on them. The ultimate stress for our bones is a break. But, our bones are amazing in that, even after most breaks, they can fully heal. Read on to learn more about the process that happens when a bone breaks and then heals. ## Bone composition: What is bone made of? Let’s start with a little anatomy. Our bones are a type of [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Like all types of connective tissue, bone tissue is made up of an extracellular matrix and the cells and fibers which exist within that matrix. The extracellular matrix of bone is mostly composed of collagen and various other types of proteins. Several types of bone cells exist within that matrix: mesenchymal stem cells (sometimes called osteoprogenitor cells), osteoblasts, osteoclasts, and osteocytes. The roles of stem cells, osteoblasts, and osteoclasts are particularly important in healing a broken bone. Each bone cell type has a role in bone formation and maintenance. Stem cells are a type of cell that divide and differentiate into osteoblast cells. Osteoblasts are responsible for the creation of bone tissue. They secrete the extracellular matrix that bone cells live within. When osteoblasts mature, they become osteocytes. These are our main mature bone cells. Finally, osteoclasts are responsible for breaking down bone tissue to release minerals and nutrients that we store in our bones until our body needs to reabsorb them. They also respond to the stresses that we put on our bones and continually reshape them to our individual needs. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Why does a bone break? Most bones break due to a traumatic incident. That happens with a serious fall or other type of accident such as a car accident. Sports are also a common source of the type of injuries that cause a bone to break. Think of the significant impact of football players running into each other or a soccer player getting a strong kick to the shin. Overuse also causes some types of fractures. Long-distance runners, for example, can put so much loading stress on the bones in their [feet](https://3dmusclelab.com/exploring-the-ankle-joint/) and legs that cracks form. ## Types of fractures The technical name for a break in a bone is a fracture. There are many different types. Doctors categorize them by several factors. One of those is whether the bone goes through the skin. A closed or simple fracture means the bone doesn’t go through the skin. An open or compound fracture refers to a broken bone that punctured the skin. If it is described as a complete break, then the fractured bone is in two separate pieces. A partial break describes a broken bone that is not completely broken into more than one piece. Fractures are also described by whether or not the broken sections of bone are lined up after the break. When sections of bone line up it’s called a non-displaced break. And when the sections are not lined up, it’s called a displaced break. Doctors also describe fractures by the many different shapes that a broken bone can take. A transverse fracture is a break that goes straight across a bone. An oblique fracture is one that goes at an angle across the bone. A spiral fracture is a break that goes in a spiral around the bone. When a bone breaks on one side, but only bends rather than breaking on the other side, it’s called a greenstick. Fractures are referred to as segmental if the same bone is broken in two places. They are called comminuted if the bone is broken into three or more pieces. And, they are called compression fractures if the bone was crushed. Finally, a very thin crack in a bone is called a stress fracture or a hairline fracture. ## What happens during bone healing? ### Primary bone healing pathway Our bodies are incredibly adaptable even in situations like a bone fracture. There is more than one pathway to healing a broken bone. In primary, or direct healing, the path to healing is as the name suggests more direct, but it requires certain conditions. In that situation, the two ends of the bone need to be directly lined up, touching each other, and stabilized at the site of the break. If all of those conditions are met, then it is possible for new bone to be directly created to heal the break. However, those conditions are more often not met and in that case, our body does what is called secondary, or indirect, bone healing. ### Secondary bone healing pathway Secondary healing of a fracture is the more common situation. In this case, the broken bone goes through several stages in order to complete the healing process. Immediately after you break a bone, blood clots start forming. The blood clot helps fill the gap created at the site of the broken bone. Our body also initiates an inflammatory response. White blood cells move into the area and other aspects of our immune response help clean the area, preparing it for further stages of healing. There is overlap of course between all of the stages of healing. Generally, however, the next step is that mesenchymal stem cells create a soft fibrocartilaginous callus to replace the blood clot. Then osteoblasts derived from the stem cells create a hard callus to replace the fibrocartilaginous network. Finally, mature bone is formed and shaped at the site of the break. Any excess bone that formed during the early part of the healing process is broken down by osteoclasts. While most steps in this healing process happen in the days to weeks immediately after a bone is broken, this last step can take months to years to complete. ## What factors affect healing time? The type and location of the fracture as well as the age and health of the person affect how quickly a bone heals. Other specific factors related to the type of break that slow healing include things like a particularly large gap between the ends of the broken bone, an open fracture, a fracture that is in the transverse direction (Claes, 2021), and/or instability at the site of the break (ElHawary et al., 2021). Sufficiently stabilizing the area of the break, in particular, to avoid shearing movement helps support healing (Claes, 2021). Other factors that could slow healing include an inadequate blood supply to the injured area, smoking, and either an excessive or insufficient immune response (ElHawary et al., 2021). ## Conclusion Bones are living tissue and are constantly adapting to the stresses we put on them in daily life. Bones are an especially amazing tissue because when we experience the ultimate bone stress, a break, our bones can heal! However, the process that happens when a bone heals can be slow. It involves multiple stages and can take months to years to fully complete. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Claes, L. 2021. Improvement of clinical fracture healing – What can be learned from mechano-biological research? Journal of Biomechanics. 115:110148.](https://pubmed.ncbi.nlm.nih.gov/33341439/) [ElHawary, H., A. Baradaran, J. Abi-Rafeh, J. Vorstenbosch, L. Xu, J.I. Efanov. 2021. Bone healing and inflammation: Principles of fracture and repair. Seminars in Plastic Surgery. 35(3):198-203.](https://pubmed.ncbi.nlm.nih.gov/34526868/) [Lin X., S. Patil, Y.G. Gao, A. Qian. 2020. The bone extracellular matrix in bone formation and regeneration. Front Pharmacol. 11:757.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264100/) [Marsell, R. and T.A. Einhorn. 2011. The biology of fracture healing. Injury-International Journal of the Care of the Injured. 42:551-555.](https://pubmed.ncbi.nlm.nih.gov/21489527/) [Mohamed, A.M. 2008. An overview of bone cells and their regulating factors of differentiation. Malays J Med Sci. 15(1):4-12.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3341892/) [Sheen J.R., A. Mabrouk, V.V. Garla. Fracture Healing Overview. [Updated 2023 Apr 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551678/](https://www.ncbi.nlm.nih.gov/books/NBK551678/) --- Source: https://3dmusclelab.com/labral-tear/ Author: David Keil · Updated: 2026-05-21 Injuries # What Is A Labral Tear? ![Hip Labral Tear](https://3dmusclelab.com/wp-content/uploads/2025/12/larbral-tear.jpg) Are you confused about hip pain, shoulder pain, and labral tears? Or, maybe you know someone who has experienced a labral tear and wants to know more. What is a labrum anyway, and why would it tear? In this article, we’ll take a closer look at that important but often glossed-over structure in the hip and shoulder, the labrum. I’ll review some anatomy, explore labral function, and share some ideas about when and why a labrum might tear. Read on to learn more! ## What is a labrum? A labrum is a piece of fibrocartilaginous tissue that connects the cartilage that lines the socket of our hip and [shoulder joints](https://3dmusclelab.com/shoulder-joint-in-movement/). The labra attach to the articular cartilage and form a rim around the socket. Labrum comes from Latin and means “lip.” The hip and shoulder labra are structures that support these two ball-and-socket joints. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is a labral tear? A labral tear of either the [hip](https://3dmusclelab.com/exploring-the-hip-joint/) or shoulder labrum occurs when there is a tear to the labrum itself or when it is torn away from part of its location of attachment. Specific tears are described by their location, their particular morphology, and/or their cause. ## Hip labrum ### Functions The hip labrum is also called the acetabular labrum. The hip labrum supports multiple functions at this important joint. By providing a lip of extra fibrocartilagenous tissue around the socket, it deepens the socket of the hip joint. The labrum completes a vacuum seal around the hip joint and helps maintain joint lubrication by contributing to the distribution of [synovial fluid](https://3dmusclelab.com/synovial-joint/) in the joint. It adds to the stability and shock absorption at the hip joint. It contributes to necessary load distribution at the hip joint and helps resist too much translation of the femoral head, which could lead to dysfunctions like dislocation. Finally, the hip labrum distributes contact between the head of the femur and the cartilage of the acetabulum, reducing premature wear at the interface of those two structures. ### Hip labral tears Tears of the acetabular labrum can be the result of multiple causes. Those might include (but aren’t limited to): - Acute accidents (car accident, slip and fall, sports-related collision) - Repetitive motion actions with frequent external rotation and/or twisting through the hip joint (e.g., dance, sports) - A result of hip dysfunction or degeneration, for example, hip dysplasia, hypermobility, or femoroacetabular impingement - [Age-related wear and tear](https://3dmusclelab.com/muscles-when-we-age/) with or without other risk factors The specific relationship between hip labral tears and damage to the articular cartilage that lines the joint is unclear. The two issues are often found together, especially in older patients, but whether one causes the other is not certain. ### Symptoms of a hip labral tear Symptoms of a hip labral tear are variable. Some people report anterior hip or groin pain. Others report pain that continues into the [buttock](https://3dmusclelab.com/gluteus-maximus/), thigh, or even the [knee](https://3dmusclelab.com/knee-joint/). People may report that movement activities, including simple standing and [walking](https://3dmusclelab.com/what-is-the-gait-cycle/), but especially twisting, make the pain worse. Sometimes people also report mechanical-type symptoms, like clicking, locking, catching, or feelings of instability in their hip joint. Long-term effects may include possible hip instability, increased risk of osteoarthritis, and the potential for reduced shock absorption at the joint. ## Shoulder labrum ### Functions The shoulder labrum is also called the glenoid labrum. Remember that the glenoid fossa is the depression in the scapula that the head of the humerus fits into to create the shoulder joint. The shoulder labrum is a rim of fibrocartilagenous tissue that forms a rim on the articular cartilage that lines the glenoid fossa. You might also remember that the socket of the [shoulder joint](https://3dmusclelab.com/shoulder-girdle/) is much shallower compared to our deep hip socket. One important function of the labrum is to provide tissue that essentially deepens this socket, making for a more stable connection between the humerus and scapula. Like the labrum in the hip joint, the shoulder labrum helps resist too much translation of the humeral head within the shoulder socket. That helps maintain movement within a healthy range and helps prevent dysfunction like dislocation. It also helps provide shock absorption when we do abrupt motions at the shoulder joint, like throwing, for example. ### Shoulder labral tears As with the hip joint, tears of the glenoid labrum can result from multiple causes. Those might include (but aren’t limited to): - Acute accidents, like catching yourself with your arm in a fall - Acute sports-related movements - Repetitive motion actions (e.g., throwing sports, weightlifting) - Age-related wear and tear (may be common, but asymptomatic in certain age ranges) ### Symptoms of a shoulder labral tear Often, asymptomatic and/or [shoulder pain](https://3dmusclelab.com/rotator-cuff-muscles-shoulder-pain/) symptoms are not correlated with existing labral tears. One reference noted that between 55 and 72% of a group of asymptomatic adults aged 45-60 appeared to have a labral tear in the superior area of the labrum. However, there are also some symptoms that may be associated with labral tears. Those include shoulder pain, catching or grinding sensations when moving the shoulder, and feelings of shoulder weakness or instability. ## Diagnosis and treatment of labral tears Diagnostic tools and treatments are similar for hip and shoulder labral tears. Diagnostic imaging, including X-rays, MRI, and MRA, might be used, depending on each individual’s situation. However, these imaging tools do not reliably show all labral tears. Arthroscopy and physical exams are also used to diagnose labral tears. It’s important to note that many labral tears are asymptomatic, meaning they are present in the joint but aren’t associated with any pain or dysfunction. For that reason, not all labral tears may need treatment. If treatment is recommended, the first step in treatment is often simply resting from activities that are causing pain. In more problematic situations, physical therapy might be recommended. And, in more acute situations, surgery might ultimately be recommended. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Groh M.M. and J. Herrera. 2009. A comprehensive review of hip labral tears. Current Review Musculoskeletal Medicine. 2(2):105-17.](https://pubmed.ncbi.nlm.nih.gov/19468871/) [Schwartzberg, R., B.L. Reuss, B.G. Burkhart, M. Butterfield, J.Y. Wu, and K. W. McLean. 2016. High prevalence of superior labral tears diagnosed by MRI in middle-aged patients with asymptomatic shoulders. The Orthopaedic Journal of Sports Medicine. 4(1): 7pgs.](https://journals.sagepub.com/doi/pdf/10.1177/2325967115623212) [Varacallo M.A., D.C. Tapscott, and S.D. Mair. 2025. Superior labrum anterior posterior lesions. [Updated 2023 Aug 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538284/](https://www.ncbi.nlm.nih.gov/books/NBK538284/) --- Source: https://3dmusclelab.com/meniscus-tear/ Author: David Keil · Updated: 2025-12-17 Injuries # What Is A Meniscus Tear? ![What Is A Meniscus Tear?](https://3dmusclelab.com/wp-content/uploads/2025/06/meniscus-tear.jpg) A meniscus tear is a common injury to an important structure in the knee joint. If you’ve landed on this article, you might have experienced a meniscus tear or know someone who has. Read on to learn more about what a meniscus tear is and how it affects the [knee joint](https://3dmusclelab.com/knee-hyperextension/). ## What is the meniscus? The menisci are semi-circular pieces of cartilage located at the [proximal](https://3dmusclelab.com/anatomical-terms-location-position/) end, on the articulating surface, of the tibia (tibial plateau). Each meniscus is wedge-shaped, with a thicker area on the outside and tapers to a thinner area on the inside. The meniscus is a small but critical structure in the knee joint. We actually have two menisci, a medial and a lateral meniscus, in each knee. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Functions of the menisci The menisci function in a few different ways to support optimal movement and the integrity of our [knee joints](https://3dmusclelab.com/knee-joint/). Remember that the knee joint, or femorotibial joint, is where the femur meets the tibia. Our knee is a complex joint. It’s considered a modified hinge joint because it does more than just hinge. Although its primary actions are flexion and extension, it can also do a certain amount of internal and external rotation when it’s in a flexed position. When we [flex, extend, and rotate](https://3dmusclelab.com/anatomical-terms-for-movements/) our knees, the femoral condyles roll over the upper surface of the tibia, called the tibial plateau. The menisci provide additional glide to make that a smooth, coordinated movement. ### Other functions The menisci also contribute to shock absorption in the knee. When we [run](https://3dmusclelab.com/lateral-hip-muscles-in-movement/), for example, we put force through our knee joints that is equivalent to several times our body weight. Our menisci help absorb the shock of impact and distribute that force. They are also part of the transmission system that distributes the load that we put through our knees through the kinetic chain of the leg and into the ground. The position and type of structure of the menisci make them important structures for helping to maintain the right balance between stability and mobility of the knees. ## What is a meniscus tear? When we move in a way that puts force through the meniscus more quickly than the meniscus can adapt or shift position, we can tear fibers in that cartilage structure. That commonly happens when we pivot suddenly while we’re also weight-bearing through our knee. That can happen when playing sports, such as when we plant a foot and then turn in basketball or soccer. Even if we’re not weight-bearing, combining flexion and rotation can “twist” the meniscus, and adding even a little force or a sudden movement can tear it. The [half-lotus position in yoga](https://www.yoganatomy.com/standing-half-bound-lotus/) is one situation where this can happen. Deep flexion, as in a squat, can also put too much pressure on the meniscus, especially with the addition of sudden movement. ### Symptoms of a meniscus tear Often, when we experience a meniscus tear, there is a popping sound at the moment the tear happens, but not always. There might be some pain at the moment of the injury, but more often, soreness comes later, along with some inflammation and swelling. The area might feel stiff, or like you can’t fully flex and extend the knee. Depending on the type of meniscus tear, the knee may also get locked or stuck in position. ### Types of meniscus tears There are several different kinds of meniscus tears. The cartilage can tear either perpendicular to the tibia or horizontally, along the fiber direction. When the tear is perpendicular, it’s called a radial tear. When it’s horizontal, it’s called a horizontal tear. A bucket handle tear is a vertical tear that occurs toward the center of the meniscus and can sometimes cause issues with knee function because a section of the inner cartilage is torn away from the outer section. The section that is pulled away can sometimes get caught up in the mechanism of the knee and disrupt function. Similarly, a flap meniscus tear is one where a piece of the meniscus tears away from the rest of the structure. It can also get caught up in the mechanism of the knee joint and cause issues. Complex meniscus tears include situations where someone experiences multiple types of tears and/or has less common tear patterns. ## Why do so many people experience meniscus tears? Sports and activities that combine knee flexion, rotation, and weight-bearing can certainly increase our chances of experiencing a meniscus tear. An imbalance in tissue tension between the medial and lateral sides of our knees, like [valgus and varus patterns](https://3dmusclelab.com/valgus-and-varus-knee-pain/), can contribute to uneven loading through our knee joints. This can contribute to uneven pressure on the two menisci in each knee and make it more likely to put too much pressure on one side, especially during a sudden movement. Tension around the [hip joints](https://3dmusclelab.com/exploring-the-hip-joint/) can make it more likely that force will go into the knees in a problematic way when we combine flexion and rotation of the knee joint. Age-related degeneration of tissue in our knee joints can also increase the chances of tearing a meniscus. ## What treatments are there for meniscus tears? Each individual’s situation is unique to them. If you have experienced a meniscus tear, get a full assessment from an appropriate medical professional. They can help you understand your options and help you determine which option might best fit your situation. Treatments vary according to the size, location, and type of the meniscus tear, as well as by the specific activity level and types of activities the person does or wants to return to. Small tears to the most external portion of the meniscus have the potential to heal on their own. There is some blood supply to the fibers closest to the outside, so healing is possible. Larger and/or more internal tears won’t heal on their own because there is insufficient blood supply. Many types of meniscus tears don’t need any treatment other than being cautious when moving the injured knee. In some cases, surgery is recommended, particularly when some piece of the cartilage is loose and interfering with the function of the knee joint in [essential movements](https://3dmusclelab.com/functional-movement/) like [walking](https://3dmusclelab.com/what-is-the-gait-cycle/). ## Conclusion The menisci are important structures in our knee joints that help them function optimally. They contribute to glide between the tibia and fibula, force transmission, shock absorption, stability, and mobility at the knee joints. When we experience a meniscus tear, all of those functions at the knee joint can potentially be compromised, depending on the location, type, and severity of the tear. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Fox, A.J.S., Bedi, A., and Rodeo, S.A. 2012. The basic science of human knee menisci. Sports Health. 4(4):340-351.](https://pmc.ncbi.nlm.nih.gov/articles/PMC3435920/) [Pasiński, M., Zabrzyńska, M., Adamczyk, M., et al. 2023. A current insight into human knee menisci. Translational Research in Anatomy. 32:100259; 7pgs.](https://www.sciencedirect.com/science/article/pii/S2214854X23000286) --- Source: https://3dmusclelab.com/carpal-tunnel-syndrome/ Author: David Keil · Updated: 2025-12-17 Injuries # An Overview Of Carpal Tunnel Syndrome ![Carpal Tunnel Syndrome](https://3dmusclelab.com/wp-content/uploads/2019/07/carpal-tunnel-syndrome.jpg) Carpal tunnel syndrome occurs when the median nerve is compressed at the [wrist joint](https://3dmusclelab.com/hand-and-wrist-anatomy/) and causes a neuropathy condition. ## Which anatomical structures are involved in carpal tunnel syndrome? The median nerve is derived from the nerves at vertebrae C6, C7, C8, and T1 and then runs through the forearm into the palm of the hand. The “carpal tunnel” is a tunnel or passageway at the wrist. It’s formed from the carpal bones on the dorsal side and the transverse carpal ligament on the palm side of the hand. The median nerve as well as the flexor tendons for the forearm pass through the carpal tunnel. The median nerve innervates the thumb and first two fingers, on the palm side of the hand, as well as the median side of the fourth finger. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the symptoms of carpal tunnel syndrome? Symptoms of this condition can include tingling, numbness, and/or pain in the fingers which are innervated by the median nerve. Additionally, grip strength and general function may be reduced in the affected hand. Similar symptoms can be caused by a variety of other conditions such as: pronator syndrome, anterior interosseous nerve syndrome, thoracic outlet syndrome, cervical radiculopathy, brachial plexopathy, and central nervous system disorders among others. So, it’s very important to have a thorough evaluation of any symptoms that you experience. ## What causes carpal tunnel syndrome? Anything that reduces the space in the carpal tunnel enough that it results in the compression of the median nerve can contribute to carpal tunnel syndrome. There is some debate about what the causes are, although genetics, injuries and accidents, tumors or non-cancerous lesions, and work or sport-related repetitive movements have all been implicated. Sometimes there appears to be no clear cause. ## How is carpal tunnel syndrome diagnosed? There are several methods currently used to aid in the diagnosis of carpal tunnel syndrome. Research suggests that a combination of the available methods increases the accuracy of diagnosis because each of the individual methods alone can produce false positives and/or false negatives. A thorough intake describing the symptoms being experienced and the contexts in which the symptoms are experienced or relieved is a good first step. Other diagnostic tests used include: - Phalen’s test - Tinsel’s test - Nerve conduction studies - Diagnostic CT scale - Symptom severity scale - Functional scale - Katz hand diagram - Hand elevation test - Ultrasounds - MRI And others! ## How is carpal tunnel syndrome treated? Non-surgical treatment, usually for those with mild to moderate symptoms, can include: hand splints, yoga, mobilization of the carpal bones, steroids, corticosteroids, vitamins B6 and B12, or non-steroidal anti-inflammatory drugs (NSAIDS). In the surgical treatment, the transverse carpal ligament is cut to make space in the carpal tunnel. The procedure is called a carpal tunnel release. As with any condition, consult the appropriate professional to do a thorough examination of your symptoms if you are concerned about carpal tunnel syndrome. If you’d like to read more about muscle function and dysfunction sign up to our mailing list. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Ibrahim, I., W.S. Khan, N. Goddard, and P. Smitham. 2012. Carpal tunnel syndrome: A review of the recent literature. Open Orthopaedics Journal. 6:69-76.](https://www.ncbi.nlm.nih.gov/pubmed/22470412) [Kim, P-T., H-J. Lee, T-G. Kim, and I-H. Jeon. 2014. Current approaches for carpal tunnel syndrome. Clinics in Orthopedic Surgery. 6(3):253-257.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143510/) [Carpal Tunnel Syndrome Information Page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Carpal-Tunnel-Syndrome-Information-Page Accessed: June 4, 2019.](https://www.ninds.nih.gov/Disorders/All-Disorders/Carpal-Tunnel-Syndrome-Information-Page) --- Source: https://3dmusclelab.com/knee-hyperextension/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Should I Be Concerned About Knee Hyperextension? ![Knee Hyperextension](https://3dmusclelab.com/wp-content/uploads/2020/01/anatomy-of-knee.jpg) Let’s start by defining hyperextension. This is a word that can be confusing because it can be used in two different ways. The first way that the term hyperextension can be used is to describe a basic, normal movement. Hyperextension is extension past the point of “neutral” when we are standing in anatomical position. So, if I extend my arm at the shoulder joint from a flexed position and return it to my side, I have done extension of the shoulder joint. If I keep going with that movement until my arm is behind my body, I have now technically done hyperextension of the shoulder joint. There is a second way that the term hyperextension can be used, which is to describe the condition of hyperextension. This condition can describe the position of multiple different joints in the body, but is probably most commonly applied to the knee joints and the [elbow joints](https://3dmusclelab.com/elbow-joint-and-forearm/). ## Knee hyperextension Hyperextension of the knee joint means that the shape of the joint itself, where the tibia meets the femur, is extended past where we would consider “neutral” to be when we are standing in anatomical position. The chronic condition of hyperextension of the knee joints might have a genetic predisposition as a result of bone shape, and/or laxity of the tendons and ligaments that surround the knee joint. Postural patterns can also influence a habit of moving the knees to hyperextension. An acute condition of knee hyperextension could result from an accident or injury, and is often sports-related. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## When to be concerned about hyperextension of the knees If you experience a chronic pattern of hyperextended knees that is never retrained, it’s possible for problems to occur such as wearing away cartilage, over-stretching the posterior cruciate ligaments of the knee, or overstretching the gastrocnemius and hamstring tendons. If you have an acute condition of knee hyperextension caused by an accident or sports injury, then there may be more immediate injuries that need attention. Concern about a pattern of hyperextension at the knee joints sometimes comes up in activities where we toward ends of range of motion like [yoga](https://www.yoganatomy.com/hyperextending-the-knees-in-dandasana/) or gymnastics. But even in those activities the issue is really more of a concern when we’re weight-bearing through the knee joint. ## What to do? If you are experiencing the chronic type of mildly hyperextended knees, try cultivating a new pattern. Retrain yourself to maintain a micro bend in the knee joint to keep the surrounding muscles actively holding the knee joint in a healthy place. If you have an acute condition of knee hyperextension caused by a recent accident or sports injury, then you should see an appropriate medical professional for diagnosis and treatment. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/piriformis-syndrome/ Author: David Keil · Updated: 2025-12-17 Injuries # What Is Happening In Piriformis Syndrome? ![Piriformis Syndrome: Sciatica Pain](https://3dmusclelab.com/wp-content/uploads/2019/01/sciatica-pain.jpg) The piriformis muscle often gets a lot of press because it can be the culprit behind symptoms of pain. Many people have heard the phrase piriformis syndrome and possibly also heard it lumped together with the term sciatica. But what is piriformis syndrome? And, is it the same thing as sciatica? ## Defining piriformis syndrome Piriformis syndrome is a neuromuscular condition that occurs when some part of the piriformis muscle puts pressure on the sciatic nerve (a major nerve that runs from the lumbar spine down the back of the legs) and causes pain. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What’s the difference between piriformis syndrome and sciatica? In both piriformis syndrome and sciatica, pain is felt because something is pressing on the sciatic nerve. Generally, you can distinguish between these two conditions based on the source of what’s creating the pressure on the sciatic nerve. In the case of sciatica, what’s pressing on the sciatic nerve is located in the spine. It’s often bone, specifically one or more vertebrae in the back, but it could also be a vertebral disc itself that is pressing on the sciatic nerve, due to a disc herniation or other spinal issue. In the case of piriformis syndrome, what’s pressing on the sciatic nerve is muscle, specifically, the piriformis muscle. It’s important to distinguish between the two because even though the pain may feel very similar, the treatment is different. If you think you may be experiencing either piriformis syndrome or sciatica, see your doctor. Therapies range depending on the specific situation and can vary from surgery to appropriate stretching of piriformis to physical therapy. ## What causes piriformis syndrome? Piriformis syndrome can have several different causes. They are sometimes grouped into primary and secondary types. Primary causes are those related to an unusual location of the sciatic nerve with respect to the location of the piriformis muscle, for example, when part or all of the sciatic nerve runs through the piriformis muscle, rather than inferior to it, which is the more common path. Secondary causes are those that occur as a result of activities that may overuse the muscle (like running), as a result of accidents, or as a result of a habit that compresses the nerve, such as prolonged sitting in a car or sitting on your wallet when it is in your back pocket. ## What are the symptoms of piriformis syndrome? Because there is considerable variation in the causes of piriformis syndrome, there is also a lot of variability in the specific locations and situations that cause pain. Some of the most common symptoms of piriformis syndrome include pain in one or both buttocks and possibly down the back of the leg. Pain when sitting for a long time is also very common. A quick way to gain more information about the likely cause of pressure on the sciatic nerve is this: 1. Lie on your back with both legs straight on the floor. 2. Now, lift one leg up while keeping it straight. 3. Can you lift your leg more than a few inches off the floor before you feel any pain? If you answered yes, then the culprit is more likely to be muscular. But if even a small lift of the leg produces pain, then the culprit is more likely to be bone. Either way, if you are experiencing frequent or constant pain, you should see your doctor to rule out causes of sciatica, such as a herniated disc or a vertebra pressing on the sciatic nerve, and to find a course of treatment that is appropriate for you. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## Further reading If you want to learn more about what the piriformis muscle is and what it does, check out the other articles in our series on the piriformis muscle: [The Piriformis Muscle](https://3dmusclelab.com/piriformis-muscle/). --- Source: https://3dmusclelab.com/scar-tissue/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is The Role Of Scar Tissue In The Body? ![Scar Tissue](https://3dmusclelab.com/wp-content/uploads/2019/04/scar-tissue.jpg) When we “tear” a muscle, we are often told that what is created in the healing process is called scar tissue. If we accidentally cut ourselves, scrape a knee, or otherwise damage our skin, we can often even see the scar that forms as the cut or scrape heals. But, what *is* scar tissue and why does it form? ## Scar tissue is connective tissue When we tear a [muscle](https://3dmusclelab.com/what-is-a-muscle/) like our hamstrings, or sprain an ankle, what we actually tear is one or more layers of [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/). Scar tissue is also connective tissue. It’s the kind of connective tissue that the body uses to repair the damaged connective tissue. It can form on the surface of the skin, when we scrape a knee for example, and it can also form internally, when we damage a muscle, tendon, ligament, or other soft-tissue structure. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## How is it formed? When we tear a muscle, our body cues specific types of cells called fibroblasts, which make the components of connective tissue, to quickly create new connective tissue to repair the tear. When each layer of fascia in and around our muscles is originally laid down, the fibers all go in the same direction. When we tear [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/) though, the scar tissue is laid down across the torn fibers in a less organized pattern. It is laid down in what is often described as a “cross-hatch” type of pattern. This creates the most secure repair of the damaged area. ## How to work with scar tissue Although the cross-hatching pattern of newly laid-down scar tissue does a great job of repairing the damaged area, it also creates some tension in that same area when the new fibers pull the original connective tissue fibers together so they can heal. Depending on the extent of the injury or damage to the area, the tension caused by the cross-hatching pattern of the newly laid down tissue can impact range of motion and muscle movement. As soon as it is safe to move the injured area (and after you have permission from your doctor if you have a more serious injury), the best way to begin to realign the scar tissue fibers with the surrounding fascia, and reduce the tension in the area, is to gently move the area. If you have a serious injury, the medical professionals who are overseeing your care will recommend physical therapy or other movement therapy that’s appropriate for your situation. Additionally, there are [types of manual therapy](https://wheelerfascialwork.com/scarwork/) that can help realign those cross-hatching fibers. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/temporomandibular-joint-disorder/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is Temporomandibular Joint Disorder? ![Temporomandibular Joint Disorder or TMJ Disorder](https://3dmusclelab.com/wp-content/uploads/2024/05/tempromandibular-joint.jpg) Temporomandibular joint disorder is one of the most common reasons for jaw pain aside from acute trauma issues, like a car accident or fall. However, many people are confused about what this disorder actually is. In this article, I’ll explain first what the temporomandibular joint is. Then I’ll explain further what both function and dysfunction include at this important joint. Read on to learn more. ## What is the temporomandibular joint? The temporomandibular joint is where a depression in the inferior part of the temporal bone, called the glenoid fossa (or sometimes the mandibular fossa) of the temporal bone, meets a bony protrusion, called the mandibular condyle, on the superior end of the branch of bone (ramus) of your mandible (jaw bone). You have two of these joints, one on each side of your jaw. It’s a hinge type of [synovial joint](https://3dmusclelab.com/synovial-joint/) that includes an articular disc to help manage force transmission and movement at this joint. This joint is critical for opening and closing your jaw, like when you’re chewing or speaking. The opening and closing movements are called elevation and depression, anatomically. In addition to those movements, this joint allows the jaw to move forward (protraction) and back (retraction), and it also moves the jaw from side to side, called right and left lateral deviation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Bones to know There are many small, interestingly-shaped bones that come together to create the complex architecture of our jaw and cranium. In this article, we’ll focus on two bones in particular, the temporal bone and the mandible. These are bones most people are familiar with, even if they don’t know their names. Your temporal bone is a large bone at the side of your skull. It’s narrower at the distal end. But, from these small more pointed areas, it widens out into a rounded shape that occupies most of the space on the side of your head. You’re probably familiar with the upper part of this bone as your “temple.” It’s that area you might massage a bit if you’ve been sitting at the computer too long. Your mandible is your jawbone. It’s the bone that your lower set of teeth are set within. ## Muscles of the temporomandibular joint The main muscles that are important for moving the temporomandibular joint are the [muscles of mastication](https://3dmusclelab.com/jaw-muscles/) (chewing). Those include the masseter, temporalis, lateral pterygoids, and the medial pterygoids. Some of the muscles of the hyoid group (digastric, geniohyoid, and mylohyoid) also assist with some of the movements at the temporomandibular joint. ## Temporomandibular joint disorder The temporomandibular joint is functioning in a healthy way when it is allowing all the types of functional movement that should be available at that joint without causing pain or discomfort. When the temporomandibular joint is malfunctioning, then we can have any of the collection of disorders classified as temporomandibular joint disorder. Temporomandibular joint disorder is the general name for any of the collection of particular symptoms of dysfunction at this joint. The disorders are sometimes loosely grouped into three categories. One category of disorder is pain or dysfunction in the myofascial components of the TMJ. Another category of disorder is a malfunction of, or other issue with, the temporomandibular joint itself. Finally, some medical sources consider headache-related TMJ disorders to be their own category. ## Symptoms of temporomandibular joint disorder The most common symptoms of this group of issues with the temporomandibular joint are pain and dysfunction of the jaw. Pain might show up in the jaw muscles or the joint itself. Some people experience pain in the face, [neck](https://3dmusclelab.com/the-deep-neck-muscles/), or even in areas more distant from the TMJ, such as the [shoulders](https://3dmusclelab.com/shoulder-joint-in-movement/) and back. Headaches are also a symptom often associated with this group of disorders. Dysfunction of the joint often includes clicking, popping, or locking of the joint. ## Causes of TMJ disorder The causes of TMJ disorders are mostly unknown. There are cases when an acute injury such as an accident results in a temporomandibular joint disorder. However, the larger majority of cases seem to arise from no one specific cause. While some research has found morphological changes in the TMJ and surrounding [myofascia](https://3dmusclelab.com/what-is-muscle-fascia/), it’s unclear whether the morphological changes were a result of a TMJ disorder or the cause of it. Research suggests that TMJ disorder often results from several interrelated factors that include psychological contributors such as stress as well as physical causes. Soft tissue issues such as an imbalance in tension between the [musculature](https://3dmusclelab.com/what-is-a-muscle/) on the two sides of the head, [neck](https://3dmusclelab.com/neck-muscles-superficial/), and jaw, as well as myofascial trigger points, can also contribute to symptoms that fit within the category of TMJ disorder. ## Diagnosis of temporomandibular joint disorder If you are experiencing TMJ disorder symptoms, of course, seek out a full assessment from a medical professional. Diagnosis tools vary among individual medical practitioners. Some use the recently created diagnostic tool, the Diagnostic Criteria for Temporomandibular Disorders. That tool includes both a physical exam as well as a screen for other related factors such as psychological factors. Regardless of the specific tool used, most exams will include some combination of a physical exam and an intake to gather information about other related potential contributing factors. Depending on your particular symptoms and their severity, your medical professional might also recommend getting some images to help diagnose your specific TMJ disorder. Common types of imaging include MRI, CT scan, and more recently, ultrasounds. ## Treatment of TMJ disorder The focus of temporomandibular joint disorder treatment is on eliminating pain, restoring function, and minimizing any potential long-term issues that could arise from dysfunction. Those might be issues such as morphological changes to the jaw or soft tissue. Initial treatments focus on eliminating pain by changing daily habits that contribute to pain. That includes things like eating softer food to rest the jaw and chewing muscles, not chewing gum, and addressing issues like tooth-grinding, etc. Cold or warm packs can also help reduce pain. Non-steroidal anti-inflammatory (NSAID) options like many over-the-counter pain relievers might also be recommended to reduce pain in the short term. Some types of TMJ disorders resolve without any further treatment needed. However, depending on your particular type of TMJ disorder, your doctor might also recommend manual therapies, physical therapy, and or splinting of the jaw to reduce pressure on the temporomandibular joint. As a last resort, and only in the case of certain types of temporomandibular joint disorders, your doctor might suggest surgery. ## Conclusion Temporomandibular joint disorders are a group of disorders that share the symptoms of TMJ pain and dysfunction. There is no single specific cause for this array of disorders. What is most likely is that multiple interrelated factors interact to result in the symptoms associated with TMJ pain and dysfunction. If you are experiencing symptoms of TMJ disorders, seek a full assessment from an appropriate medical professional. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [National Institute of Health. (Accessed 2023, May). *TMD (Temporomandibular Disorders)*. National Institute of Dental and Craniofacial Research, National Institute of Health. https://www.nidcr.nih.gov/health-info/tmd](https://www.nidcr.nih.gov/health-info/tmd) [Maini K, Dua A. Temporomandibular Syndrome. [Updated 2023 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551612/](https://www.ncbi.nlm.nih.gov/books/NBK551612/) [Palmer, J. and J. Durham. 2021. Temporomandibular disorders. British Journal of Anaesthesia Education. 21(2):44-50.](https://pubmed.ncbi.nlm.nih.gov/33889429/) [Park, B-R., J-A. Gim, and K-W. Baek. 2023. Improvement of the pain of temporomandibular disorder in parts of the human body through temporomandibular joint correction treatment. Physikalische Medizin, Rehabilitationsmedizin, Kurortmedizin. 33:352–357.](https://www.thieme-connect.com/products/ejournals/pdf/10.1055/a-1840-9458.pdf) [Pihut, M., G. Andrzej, R. Obuchowicz, and K. Chmura. 2022. Influence of ultrasound examination on diagnosis and treatment of temporomandibular disorders. Journal of Clinical Medicine. 11:1202. 9pgs.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911463/) --- Source: https://3dmusclelab.com/muscles-affected-in-scoliosis/ Author: David Keil · Updated: 2025-12-17 Injuries # What Muscles Are Affected In Scoliosis? ![Muscles in Scoliosis](https://3dmusclelab.com/wp-content/uploads/2023/05/scoliosis.jpg) Scoliosis is a particular kind of spinal bend pattern in the body. It’s a complex condition with many different causes and a variety of expressions in the population. It can be present at birth, or caused by acute trauma, disease, and other factors. Because [the spine](https://3dmusclelab.com/exploring-the-spine/) is so central to our structure, scoliosis affects and is affected by many different muscles, both superficial and deep. In this article, we’ll take a brief look at the muscles most directly affected. ## What is scoliosis? Scoliosis refers to a condition of the spine where a section of the spine is laterally curving at least 10 degrees in the coronal plane. In this kind of pattern the spine is usually curving laterally and rotated. With this definition in mind, you might be able to think of many people you know whose small curves in the spine would be considered a scoliosis pattern. However, most of those incidences are mild and don’t require any treatment. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What causes scoliosis? While some specific causes include various diseases, disorders, or physical traumas, most scoliosis patterns have no known cause. Specifically, there are congenital, neuromuscular, syndrome-related, idiopathic, and other reasons which cause scoliosis (Janicki et al., 2007). The most common kind has no known specific cause and is referred to as idiopathic scoliosis. Researchers think that the idiopathic type is most likely caused by some combination of genetic and environmental factors (Kim et al., 2009; Hermus et al., 2007). In the case of idiopathic scoliosis, it’s a bit like the chicken and egg story. It’s possible for some environmental cause to result in a spinal curve which then affects the muscle tension balance around our spine and up and down the kinetic chain. And, it’s possible for activities, habits, injuries, and accidents to result in changes in muscle tension balance which results in a spinal curve. ## What does scoliosis look like? It’s important when we think of scoliosis and muscles that we think three-dimensionally. Our spine moves in all three planes and in complex combinations of those planes. A scoliosis can similarly occur in all three planes or some combination of those. We commonly find for example some combination of a sidebend and a rotation in one or more sections of the spine. A scoliosis can have a single curve (referred to as a C-curve) or more than one curve. ## Relationship between muscles and bones One way to consider our body is as a [tensegrity structure](https://en.wikipedia.org/wiki/Tensegrity). Tensegrity is a design principle where tensional members maintain the positioning of structural members. In our body we could consider our bones to be structural members and our soft tissue to be tensional members. We have bones that are held in place by the tension of our soft tissue ([muscles](https://3dmusclelab.com/what-is-a-muscle/), [fascia](https://3dmusclelab.com/what-is-muscle-fascia/), and other [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/)). This means that there is a relationship between how our bones are positioned and how we’re holding tension in our muscles and fascia. So, [muscle tension](https://3dmusclelab.com/muscle-contractions/) of spinal muscles on both the convex and concave sides of a spinal curve is affected by the position of the bones. Specifically, the spinal muscles are generally short and tight on the concave side and long and tight on the convex side of the curve. ## Which muscles are most affected? Basically, all the muscles that attach to the spine are directly affected by a scoliosis. More superficially we find muscles that attach to and move the spine like splenius capitis, splenius cervicis, and the [erector spinae group](https://3dmusclelab.com/erector-spinae-muscles/), including iliocostalis, longissimus, and spinalis. At a deeper level, we find another layer of spinal muscles including the multifidus, rotatores, and semispinalis capitis. And at the very deepest layer of musculature next to the spine, we also have some very tiny muscles called the intertransversarii group which are located between adjacent transverse processes or adjacent spinous processes. They also contribute to spinal movement. We also have other deeper muscles which attach to the spine, but whose primary jobs are much broader than spinal movement. However, our spinal position still affects those muscles. Those include muscles like the quadratus lumborum, [psoas major](https://3dmusclelab.com/iliopsoas-muscle-anatomy/), and the diaphragm. ### Other muscles affected Indirectly you could imagine that the whole rest of the body is affected in some way when there is a lateral curve and/or rotation in the spine. The position of the head is affected because the spine is the base that our head sits on. So an imbalance in the spinal muscles would be reflected in the position and muscle tension at the head and neck. The position of the spine will affect the tension and shape of the abdominal container and associated muscles including the rectus abdominis, external obliques, internal obliques, and the transverse abdominis. The position of the spine also affects breathing-related muscles like the external and internal intercostals as well as the diaphragm which is directly affected by spinal position because it is attached to the spine. You could also imagine that the shoulder girdle position would be affected by spinal position since our shoulders hang off of our torso. So differences in the tension of our [shoulder girdle muscles](https://3dmusclelab.com/shoulder-girdle/) could be indirectly affected by a scoliosis pattern. That could especially include muscles like the [trapezius](https://3dmusclelab.com/trapezius-muscle/), [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), rhomboids, and serratus posterior. Finally, the position of our spine will also have some effect on the position of our [pelvis](https://3dmusclelab.com/exploring-the-pelvis/). So there will likely be some differences in tension in muscles on each side of the pelvis. ## What is done to manage scoliosis? Basic scoliosis treatment falls into three main categories. In the first doctors don’t actively apply any treatment. They observe to see if the condition worsens to the point that treatment is necessary. The second option is bracing to try to prevent the spinal curve from getting worse, particularly while children or adolescents are still growing. The third treatment is surgery to reduce the spinal curvature. More specific details on the causes and treatments of scoliosis are beyond the scope of this article. ## Conclusion Scoliosis is a lateral curve of the spine of 10 degrees or more usually combined with a rotation in the spine. Because our spine is so central to our body, a scoliosis affects our whole body in some way. The muscles most directly affected include all of the layers of spinal muscles from the most superficial to the deepest. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Hermus, J.P.S., L.W. van Rhijn, and A. van Ooij. 2007. Non-genetic expression of adolescent idiopathic scoliosis: a case report and review of the literature. Eur. Spine J. 16(Suppl3):S338–S341.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2148088/) [Janicki, J.A. and B. Alman. 2007. Scoliosis: Review of diagnosis and treatment. Paediatr Child Health 12(9):771-776.](https://pubmed.ncbi.nlm.nih.gov/19030463/) [Kim, H.J., J. S. Blanco, and R. F. Widmann. 2009. Update on the management of idiopathic scoliosis. Current Opinion in Pediatrics. 21:55–64.](https://pubmed.ncbi.nlm.nih.gov/19242241/) --- Source: https://3dmusclelab.com/anatomical-terms-for-movements/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Anatomical Terms For Movements ![Anatomical Terms for Movement](https://3dmusclelab.com/wp-content/uploads/2024/11/anatomical-terms-1.jpg) An essential part of [learning](https://3dmusclelab.com/whats-your-learning-style/) and [studying kinesiology](https://3dmusclelab.com/5-tips-for-learning-kinesiology/) is being able to communicate about it. Similarly to what I discussed in my last article about the [anatomical terms we use for location](https://3dmusclelab.com/anatomical-terms-location-position/) in the body, we also have anatomical terminology for movement. In this article, we’ll explore the language we use to clearly describe different types of movements in the body. ## Basic movements In the world of anatomy and [kinesiology](https://3dmusclelab.com/what-is-kinesiology/), we have terms for basic movements that occur at multiple joints. We also have specialized terms for very specific movements that occur only at individual unique joints. Let’s start our tour of anatomical terms for movement with the basic movements that take us out of and return us to [anatomical position](https://3dmusclelab.com/anatomical-position/). You’re probably familiar with many of these already. ### Flexion and extension We use the terms flexion and extension to describe movement at several joints like the [knee](https://3dmusclelab.com/knee-joint/), hip, [elbow](https://3dmusclelab.com/elbow-and-forearm-in-movement/), [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/), and others. Most generally, the term flexion means a movement that reduces the angle of a joint. For example, if I flex my [elbow joint](https://3dmusclelab.com/elbow-joint-and-forearm/), I bring my forearm closer to my upper arm. That action decreases the angle of the [elbow joint](https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/). The term extension refers to the opposite. Extension describes a movement that increases the angle of a joint. If I extend my [knee joint](https://3dmusclelab.com/knee-hyperextension/), my lower leg moves farther away from my thigh. That action increases the angle of the knee joint. Flexion and extension are movements that happen in the [sagittal plane](https://3dmusclelab.com/planes-of-movement/). ### Other types of flexion We also have some variations on the term flexion that describe specialized movements that only occur at specific [joints](https://3dmusclelab.com/synovial-joint/). Lateral flexion is the anatomical term that we use to describe side bending. That movement happens in the frontal or coronal plane. It is used to describe side bending of our [spine](https://3dmusclelab.com/exploring-the-spine/) in the torso or the lateral bending of our head on our neck. Dorsiflexion and plantarflexion describe movements of the foot that happen at the ankle joint. If you plantar flex your ankle, you take your toes farther away from the front of your foreleg. Colloquially, we refer to this as “pointing our toes.” If you dorsiflex your ankle, you bring your toes closer to the front of your foreleg. The term dorsiflexion is also used along with the term palmarflexion to describe movements of the hand at the wrist. When we use the term dorsiflexion to describe wrist movement, we are referring to the movement at the wrist that brings the back of our hand closer to our forearm. Palmarflexion, as it’s name suggests, is the term for wrist movement that brings the palm side of our hand closer to our forearm. We can also use the more general terms flexion and extension to describe the movement of the hand at the wrist in the sagittal plane. But, you will sometimes see these more specific terms used, so it’s helpful to understand what they refer to. ### Adduction and abduction Adduction and abduction describe movements that happen at many joints in the frontal or coronal plane. Adduction is a movement that brings a structure closer to the midline of our body. Abduction is the opposite. If we abduct a structure, we move it farther from the midline of our body. If you lie on your back to make a snow angel in the winter, you are abducting your arms and legs when you take them away from you. You are adducting your arms and legs when you bring them back into your body. We are most familiar with adduction and abduction movements that happen at our [shoulder](https://3dmusclelab.com/shoulder-girdle/) and [hip joints](https://3dmusclelab.com/exploring-the-hip-joint/), but there are other joints in the body where these movements happen such as some of the small joints we use to move our fingers toward and away from each other. ### Other types of adduction Horizontal adduction is also sometimes referred to as horizontal flexion. It is a movement in the transverse or horizontal plane. It’s usually used to describe the action at the shoulder joint when our arm is already in a flexed position and we bring it closer to the midline horizontally. ### Rotation Rotation is the anatomical term for turning a structure around an axis in the transverse or horizontal plane. You are probably most familiar with the rotation that we do at the two ball and socket joints in our body, the hip and the shoulder joints. In addition to movement at our ball and socket joints, we can also use the anatomical term rotation to describe turning our head on our neck or twisting our spine. We can use more specific terms to describe the direction of rotation. Medial rotation, also called internal rotation, is the anatomical term used to describe rotating our leg or our arm toward the midline of our body. Lateral rotation describes the opposite movement. Lateral rotation, also referred to as external rotation, describes a rotational movement away from the midline of our body. ### Special types of rotation In addition to the general anatomical term rotation, we have some specific terms for particular types of rotation. Circumduction is a special type of rotation that combines flexion/extension with abduction and adduction movements to move a limb in a circle at a ball and socket joint. If we move our arm in a circle through what we might think of as its full range of motion, that is circumduction. Pronation and supination are anatomical terms specifically used to describe the rotation of the forearm at the radioulnar joints. When we rotate our forearm in the direction that brings our palm up, that is supination. When we rotate our forearm in the opposite direction which brings our palm down, that is pronation. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Anatomical terms for specialized movements Throughout our body, we have examples of uniquely constructed joints that require specialized movements. Many of those movements have a name. While there are too many examples to include every one of these specialized movement terms here, I have included a few of the more common ones that you are more likely to encounter. ### Elevation and depression The anatomical terms for movement, elevation and depression, are used to describe movements of the [scapula](https://3dmusclelab.com/scapula/) as well as [the jaw](https://3dmusclelab.com/jaw-muscles/). When we draw our scapulae or our mandible down, that is called depression. The opposite, when we lift a scapula or our jaw, is called elevation. ### Inversion and eversion Inversion and eversion are anatomical terms for movement that happens at the [ankle joint](https://3dmusclelab.com/exploring-the-ankle-joint/), specifically the subtalar joint. Inversion and eversion are side-to-side movements that happen in the frontal plane. In eversion, we are bringing the top of our foot closer to the midline of the body. When we do inversion, we are bringing the top of the foot farther away from the body. ### Radial and ulnar deviation Deviation is a specialized movement that happens only at the [wrist joint](https://3dmusclelab.com/hand-and-wrist-anatomy/). This side-to-side movement at our wrist is a variation on abduction and adduction. Deviation happens when the carpal bones move relative to the radius (one of the two forearm bones). Sideways movement at the wrist toward the thumb side is called radial deviation. Sideways movement at the wrist toward the pinky side is called ulnar deviation. ### Protraction and retraction Like elevation and depression, protraction and retraction are anatomical terms used to describe the movement of the scapulae and the mandible. The term retraction describes the movement of bringing either a scapula or the jaw more posterior, closer to the back of our body. With respect to the scapulae, retraction would bring them closer to the spine. Protraction is the term for drawing either the scapulae or the mandible forward. ## Conclusion Our bodies are complex, with an array of unique movements that allow us to do everything from shrug our [shoulders](https://www.yoganatomy.com/shoulder-pain-injury-in-yoga/) to drive a car. Describing and communicating this complexity of movement requires a shared language. Anatomical terms for movement help us clearly communicate what and how we’re observing movement in the body. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/iliopsoas-and-movement/ Author: David Keil · Updated: 2025-12-17 Movement # Iliopsoas And Movement ![Iliopsoas and Movement](https://3dmusclelab.com/wp-content/uploads/2019/01/psoas-muscle-movement.jpg) Iliopsoas and movement are intertwined in many ways in our body. Iliopsoas is not just related to the possible kinds of movement we can do; it’s intimately related to our quality of movement. Considered by many the key core postural muscle, our relationship with our iliopsoas influences whether our movement is light, easeful and efficient, or something else. Because of its location and relationship with other muscles and tissues in the body, there are few actions or activities where [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/) is not involved. We’d find it difficult to do even everyday tasks without a functional iliopsoas, since this is the muscle primarily responsible for walking. Let’s look more closely at the relationship between the iliopsoas and movement. ## Iliopsoas and movement: actions and restrictions Anatomically, the iliopsoas: - Flexes the hip joint (in fact, the iliopsoas is the strongest hip flexor in the body!) - Externally or laterally rotates the hip joint. - Assists in lateral flexion of the body (side-bending). Iliopsoas restricts: - Extension of the hip joint. - Internal or medial rotation of the hip joint. Iliopsoas and movement are intimately linked. It is one of our primary muscular controls over locomotion—you can’t walk, run, or crawl without involving this muscle. Remember that the psoas major portion of the iliopsoas spans more joints than any other muscle in the body. It crosses nine joints: T12–L1, L1–L2, L2–L3, L3–L4, L4–L5, L5–sacrum, sacrum–ilium (SI joint), pubic symphysis, and the hip joint. This means that it can impact indirectly even more types of movement than it initiates directly. Just as important as the actions that iliopsoas initiates, is its role in stabilizing the pelvis. It works with other muscles to maintain just the right balance of tension at the pelvis. The iliopsoas works in relationship with its synergists (muscles doing the same action) and antagonists (muscles doing the opposite action) to allow a healthy range of flexion, extension, adduction, abduction, and rotation of the hip joint, as well as anterior and posterior tilt of the pelvis. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Iliopsoas and movement quality The iliopsoas affects not just the movement that we do—flexion, extension, etc.—but just as importantly, it affects the *quality* of our movement. It directly impacts the grace and lightness of our movement because of its relationship to our center of gravity. Iliopsoas is one of our primary muscular controls over our center of gravity. It both crosses over and lays on either side of our center of gravity, which is located near the top of our sacrum. Because of its location across our center of gravity, it affects our sense of balance and our sense of being able to move with ease through space. ## Iliopsoas and the core Because of its location and the number of joints it crosses, iliopsoas is a key part of movement from what is often called “the core”. Definitions of which muscles and structures are included in the core vary, but iliopsoas is a central part. We often have an idea, from watching dancers, gymnasts, or [accomplished yoga practitioners](https://www.yoganatomy.com/uddiyana-bandha-anatomically-speaking-by-david-keil-2010/) perhaps, that moving from “the core” is an ideal. And, in fact, it does make sense to use our body’s muscular effort to move in a way that is to our own biomechanical advantage. But how does that work? What would it feel like to initiate movement from iliopsoas? ## Exploring your felt sense of movement from iliopsoas Are you curious to have the experience of moving from the iliopsoas yourself? Try this exercise: First, take a walk around the room. Don’t try to “do” anything in particular, just walk in a way that feels like your regular walk. Next, you need to locate your iliopsoas. Review or read: “[How to contact your iliopsoas](https://3dmusclelab.com/contact-your-iliopsoas-muscle/)”. Finally, after finding your own iliopsoas, hold your attention on the area of your body where you contacted your iliopsoas and begin to walk around the room again. Have the intention of directing the movement from deep in the body where you contacted your iliopsoas muscle. What do you notice? In what ways does it feel different or similar to moving without this conscious intention? ## Iliopsoas in action If you want to learn more about the [iliopsoas](https://3dmusclelab.com/iliopsoas-muscle-anatomy/), besides iliopsoas and movement, check out our article series on this muscle, including, [How to Contact Your Iliopsoas](https://3dmusclelab.com/contact-your-iliopsoas-muscle/) and [How Iliopsoas Might Be Related To Your Back Pain](https://3dmusclelab.com/how-iliopsoas-might-be-related-to-your-back-pain/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/rotator-cuff-muscles-and-movement/ Author: David Keil · Updated: 2025-12-17 Movement # How Do The Rotator Cuff Muscles Support Movement In The Body? ![Rotator Cuff Muscles In Movement](https://3dmusclelab.com/wp-content/uploads/2020/05/rotator-cuff-posterior.jpg) In our previous article we went over the most commonly reported movements of the [rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles/). In this article we’ll dig a little deeper and take a tour through what researchers report about how the rotator cuff muscles support movement in the body in real life. We’ll look at how the rotator cuff muscles work together to do an important job and what other movements they can assist with beyond their most basic actions. We’ve previously written about the origin, insertion, and main actions of the [rotator cuff group of muscles](https://3dmusclelab.com/rotator-cuff-muscles/). But, you already know that individual muscles don’t act alone when we’re doing organic movements in daily life. There are always additional muscles that act as synergists to create a particular movement and other muscles that act as antagonists that resist a movement. Additionally some muscles assist in creating an action rather than act as the prime mover. In this article we’ll dig a little deeper and look more specifically at where and how the rotator cuff muscles contribute to movement. ## Why do we have a rotator cuff at all? The glenohumeral joint allows for a greater range of movement than any other joint in the body (Chaitow and DeLany, 2008). This particular ball and socket joint has a shallow socket (the glenoid fossa of the scapula), where the ball (the head of the humerus) sits much more outside the surface area of the socket than in our other ball and socket joint, the hip joint. All this available mobility is important to allow us to reach our arm in every direction and place our hands in position to do all kinds of vital everyday movements from eating to driving to brushing our hair to using tools. All of this mobility could be problematic however, if we didn’t have muscles that also contribute to stability of the shoulder joint. This is why the healthy functioning of our rotator cuff muscles is so important. Researchers have suggested that the existence of our rotator cuff is directly related to supporting the movements that we do. Those researchers who looked at the evolution of the four muscles that make up the rotator cuff found that quadruped species (like cats and dogs) do not have a true rotator cuff (Sonnabend and Young, 2009). The four individual muscles are still present, but their tendons do not come together to form the blended tendons that create the “cuff” over the glenohumeral joint that we’re familiar with as the rotator cuff. The true rotator cuff was only found in more advanced primates (Sonnabend and Young, 2009). The researchers have suggested that the reason for the anatomical change that occurred in advanced primates was due to their habit of frequent overhead reaching actions as well as the action of reaching out to the side. These are both actions that quadrupeds do not do (Sonnabend and Young, 2009). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What does the rotator cuff do? ![Rotator Cuff Muscles In Movement](https://3dmusclelab.com/wp-content/uploads/2020/05/rotator-cuff-anterior.jpg) What do the four [rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles/) (supraspinatus, infraspinatus, teres minor, and subscapularis) do exactly? The rotator cuff muscles contribute to maintaining the balance of tension around the glenohumeral joint and maintaining the head of the humerus securely in the glenoid fossa (Dark et al., 2007; Sangwan et al., 2015). You could think of the rotator cuff muscles like guy wires that keep a central object, the head of the humerus, in balance by maintaining just the right amount of tension from each direction. One group of researchers found that the amount of force that subscapularis can generate as an internal rotator is nearly equal to the combined force of the other rotator cuff muscles, two of which are external rotators (infraspinatus and teres minor) (Keating et al., 1993). This supports the idea that the rotator cuff muscles are important for maintaining the balance of tension in all directions around [the shoulder joint](https://3dmusclelab.com/shoulder-girdle/). The four rotator cuff muscles are often listed as stabilizers of the glenohumeral joint. But what does that mean? The most current research suggests that the rotator cuff muscles actually do something more subtle than just stabilize. They prevent translation of the head of the humerus when we are moving [the shoulder joint](https://3dmusclelab.com/shoulder-girdle/) (Sangwan et al., 2015). What do we mean by the term translation? In this case, translation refers to the movement of an object (the head of the humerus) in a line in the same plane of movement, in contrast to rotation where the object rotates around a point. Preventing translation is subtly different than simply stabilizing. While we do need to keep the head of the humerus securely in the shoulder socket, we also need to allow for movement in all directions. When the rotator cuff muscles prevent translation, they’re allowing the head of the humerus to move, without letting it go too far in any one direction. Maintaining this balance of tension is important in the long-term for just generally keeping our shoulder joint healthy. It can also be particularly important if you want to do sports or activities where you frequently do overhead movements away from the body (Alizadehkaiyet et al., 2015) or where you would be weight-bearing with the upper body. Balance between the force these muscles have on the humeral head allows the humeral head to stay securely in place while still allowing us to use the arm and other shoulder girdle muscles to do strong and/or dynamic movements with the upper body (Dark et al., 2007). ## Movements and activity of the rotator cuff muscles If we think of the main job of the rotator cuff muscles as maintaining the balance of tension around the head of the humerus in all types of actions, then it wouldn’t be hard to imagine that they might contribute to other movements besides the commonly reported ones, depending on the position that the arm and scapula were in. When the arm is reaching up and out to the side (abduction), multiple rotator cuff muscles can contribute to this action, depending on the position of the arm. When the humerus is internally rotated and we abduct the arm, then infraspinatus joins in with supraspinatus to assist this action (Otis et al., 1994). When the humerus is externally rotated and we abduct the arm, the subscapularis works with supraspinatus to support that action (Otis et al., 1994). Hik and Ackland, 2019 reported that the rotator cuff muscles can also contribute weakly to depressing or elevating the humerus. Both the intensity of the movement we’re asking the body to do (Alizadehkaiyet et al., 2015; Dark et al., 2007) and the position of the body (Wattanaprakornkul et al., 2011) impact which muscles are recruited to do an action and how much of the effort they contribute to. Wattanaprakornkul et al., 2011 found that supraspinatus and infraspinatus (as well as serratus anterior, deltoids, and trapezius) were more active when the shoulder was doing flexion, but subscapularis (as well as latissimus dorsi) were more active when the shoulder was doing extension. You could also imagine that in more dynamic movements, where more overall power is needed, the rotator cuff muscles might contribute more activity generally. But, in simple and more passive movements, they might be recruited less or hardly at all. ## Why is it important to use the rotator cuff for the right job? Research suggests that part of maintaining a healthy shoulder girdle is recruiting the best muscles for the task or sport. It’s certainly possible, however, through overuse, improper form, or fatigue, for the body to recruit muscles that are not ideal as the primary source of power for that activity. In healthy study participants, Happee and Van der Helm, 1995 found that most of the energy used for the actions of flexion and extension came from the bigger thoracoscapular muscles that contribute to these actions, not the smaller rotator cuff muscles, which contributed only a small percentage of energy to those actions. Muscle fatigue can change which muscles are recruited for an action and may result in recruiting less than ideal muscles to create a movement (Alizadehkaiyet et al., 2015). In fact, Alizadehkaiyet et al., 2015 reported that insufficient strength in the muscles that do external rotation was one contributing factor to shoulder injury in sports requiring repeated overhead actions. In order to maintain that balance of tension around the head of the humerus that we’ve been talking about, there needs to be sufficient activity from each of the muscles creating that tension. If individual muscles are fatigued, then that can affect the balance of tension between them. ## Conclusion The rotator cuff group of muscles are a special group of muscles with an important job. They allow us to do so many movements, both large and small, that are a part of our day to day activities and the sports that we enjoy. While they may not be the largest or most powerful muscles in the body, they have a vital role to play every time we move our arms. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Alizadehkaiyet, O., D.H. Hawkes, G.J. Kemp, and S.P. Frostick. 2015. Electromyographic analysis of the shoulder girdle musculature during external rotation exercises. The Orthopaedic Journal of Sports Medicine. 3(11): Pgs. 1-9.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4687830/) Chaitow, L. and J. DeLany. 2008. Shoulder, Arm, and Hand. In Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition). [Dark, A., K.A. Ginn, and M. Halaki. 2007. Shoulder muscle recruitment patterns during commonly used rotator cuff exercises: An electromyographic study. Physical Therapy. 87(8):1039-1046.](https://www.ncbi.nlm.nih.gov/pubmed/17578940) [Happee, R. and F.C.T. Van der Helm. 1995. The control of shoulder muscles during goal directed movements, an inverse dynamic analysis. Journal of Biomechanics. 28(10):1179-1191.](https://www.sciencedirect.com/science/article/abs/pii/0021929094001813) [Hik, F. and D.C. Ackland. 2019. The moment arms of the muscles spanning the glenohumeral joint: a systematic review. Journal of Anatomy. 234:1-15.](https://www.ncbi.nlm.nih.gov/pubmed/30411350) [Keating, J.F., P. Waterworth, J. Shaw-dunn, and J. Crossan. 1993. The relative strength of the rotator cuff muscles. A cadaver study. The Journal of Bone and Joint Surgery. 75-B(1):137-140.](https://online.boneandjoint.org.uk/doi/abs/10.1302/0301-620X.75B1.8421011) [Otis, J.C., C.-C. Jiang, T.L. Wickiewicz, M.G.E. Peterson, R.F. Warren, and T.J. Santner. 1994. Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation. The Journal of Bone and Joint Surgery. 76-A(5):667-676.](https://www.ncbi.nlm.nih.gov/pubmed/8175814) [Sangwan, S., R.A. Green, and N.F. Taylor. 2015. Stabilizing characteristics of rotator cuff muscles: a systematic review. Disability and Rehabilitation. 37(12):1033-1043.](https://www.ncbi.nlm.nih.gov/pubmed/25116629) [Sonnabend, D.H. and A.A. Young, 2009. Comparative anatomy of the rotator cuff. The Journal of Bone and Joint Surgery. 91-B:1632-1637.](https://www.ncbi.nlm.nih.gov/pubmed/19949130) [Wattanaprakornkul, D., I. Cathers, M. Halaki, K.A. Ginn. 2011. The rotator cuff muscles have a direction specific recruitment pattern during shoulder flexion and extension exercises. Journal of Science and Medicine in Sport. 14:376-382.](https://www.ncbi.nlm.nih.gov/pubmed/21333595) --- Source: https://3dmusclelab.com/deep-six-lateral-rotators-movement/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # The Deep Six Lateral Rotators And Movement ![Deep Six Lateral Rotators And Movement](https://3dmusclelab.com/wp-content/uploads/2023/06/deep-six.jpg) The group of muscles commonly referred to as the [deep six lateral rotators](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) of the hip is a fascinating group. But, this may not be a group of muscles that you’ve heard much about. These muscles are an important group for understanding [pelvic movement](https://3dmusclelab.com/exploring-the-pelvis/). They contribute to a surprising variety of hip actions. So in this article, we’ll take a closer look at these six muscles and [what movements](https://3dmusclelab.com/functional-movement/) they contribute to. ## What muscles are included in this group? To review, this group of muscles includes: - [Piriformis](https://3dmusclelab.com/piriformis-muscle/) - Gemellus superior - Gemellus inferior - Obturator internus - Obturator externus - Quadratus femoris All of the deep six lateral rotators attach to ([originate on](https://3dmusclelab.com/muscle-origin-insertion-and-action/)) various locations on the ischium of the pelvis with the exception of the piriformis muscle. The piriformis originates on the anterior side of the sacrum. All of the deep six lateral rotators attach to (insert on) various locations of the greater trochanter of the femur at their other end. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## How do the deep six lateral rotators contribute to movement? In my previous article, I discussed some of the specific actions that these muscles do or assist with. And I also mentioned that these muscles are deep to the large gluteus maximus. Their location, deep to a very dense muscle like gluteus maximus, makes it more difficult to determine when the deep six lateral rotators are activated during particular motions with tools like electromyography (EMG). So, there is still some exploring to do to fully understand the ways that this group of muscles function during different types of activities. Aside from lateral rotation of the thigh, individual researchers and anatomists list different possibilities with respect to which additional actions these six muscles may contribute to. ### Bilateral actions One thing that it’s important to consider is whether both hips are moving together (bilaterally) or whether we’re describing actions of one hip only (unilateral action). This can change what action these muscles create. When we activate this group of muscles on both sides at the same time (bilateral action), they can contribute to extending the hip joint. If we were in a position where both legs were free to lift (an open chain position), maybe something like a locust pose in yoga, or alternating prone extensions, then the deep six lateral rotators could contribute to extending our legs at the hip joint. However, if we were standing on both feet (a closed chain position) and bilaterally activated these muscles, then they could contribute to posteriorly tilting the pelvis relative to the legs. Of course, [muscles don’t just initiate action](https://3dmusclelab.com/muscle-contractions/), they also [resist opposing muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) and actions. So we could also consider that this group of muscles, acting bilaterally, assists with resisting or opposing all the muscles that flex the hip joint. Myers, 2014 suggests we could even think of these muscles as “extensori coxae brevis,” or the short hip extensors, rather than “lateral rotators.” ### Unilateral actions If we look at unilateral actions, then we mean that one side of our pelvis is doing something different from the other side. The most straightforward movement that all six of these muscles contribute to is the one they’re named for, lateral rotation. They laterally rotate one leg at the hip joint when you’re standing, but not weight-bearing with that leg. But how often do we actually stand on one leg and then laterally rotate the other one? This might come up for the dancers reading this, but not so often for the rest of us. What’s more likely is that we all walk. And these muscles contribute to laterally rotating one hip as we take a step (Myers, 2014). But, just like I discussed with respect to the contributions of this muscle group to posterior pelvic tilt, when we change our ideas of origin and insertion, we can see that these muscles as a group could also move the pelvis around the leg. ### Other movements As I’ve already alluded to, how the deep six lateral muscles act in movement depends on the position of the body. It’s important that we remember that our body is three-dimensional! For example, Chaitow and DeLany, 2011 refer to a “piriformis paradox.” In open chain, unilateral movement, the piriformis does lateral rotation of the thigh when the hip joint is extended or flexed less than about 60 degrees. But, he suggests that when the hip is flexed more than 60 degrees, piriformis can actually contribute to internal rotation (Chaitow and DeLany, 2011). Similarly, Yoo et al., 2015 and Chaitow and DeLany, 2011 both report that obturator internus, gemellus superior, and gemellus inferior all contribute to abduction of the thigh when the hip is flexed. ## Conclusion While we might have an idea that everything is already known about human anatomy and how our muscles work, this is often far from true. The human body is fascinatingly complex. And, there is a lot we still don’t know about what’s happening with our muscles when we move. Our deep six lateral rotators are one of those groups of muscles that we are learning more about. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Chaitow, L. and J. DeLany. 2011. The Hip. In Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition).](https://www.sciencedirect.com/book/9780443068157/clinical-application-of-neuromuscular-techniques) [Myers, T., 2014. ‘The Deep Six, Part 1’ In The Anatomist’s Corner: Issues in Structural Anatomy. pgs.157-162.](https://www.anatomytrains.com/product/the-anatomists-corner/) [Yoo, S., I. Dedova, and N. Pather. 2015. An appraisal of the short lateral rotators of the hip joint. Clinical Anatomy. 28:800-812.](https://pubmed.ncbi.nlm.nih.gov/26032283/) --- Source: https://3dmusclelab.com/elbow-and-forearm-in-movement/ Author: David Keil · Updated: 2025-12-17 Movement # How Do The Elbow And Forearm Contribute To Daily Movements? ![The Elbow And Forearm In Movement](https://3dmusclelab.com/wp-content/uploads/2020/05/rotator-cuff-door-knob.jpg) Let’s break down some real-life elbow and forearm movements. In our previous article, [Exploring the Elbow Joint and the Forearm](https://3dmusclelab.com/elbow-joint-and-forearm/), we took a look at the major bones, joints, and muscles that make movement of the elbow and forearm possible. Now let’s apply those basics and look at some examples of how we use the elbow and forearm in daily life. To review: the elbow actually consists of multiple joints. We have two joints that create the flexion and extension movement of the elbow: the humeroulnar joint and the humeroradial joint. These are the places where the two forearm bones meet the upper arm bone. We have another joint, the proximal radioulnar joint that allows for rotation of the forearm, known as pronation and supination. There are eight muscles that cross one or more of these joints, including: Flexors of the elbow: - Biceps brachii - Brachialis - Brachioradialis Extensors of the elbow: - Triceps brachii - Anconeus Pronators of the forearm: - Pronator teres - Pronator quadratus - Brachioradialis (assists pronation) Supinators of the forearm: - Supinator muscle - Biceps brachii (assists supination) ## Elbow and forearm movements in daily life So, let’s apply our understanding of the basic movements at the elbow joint to some more complex movements from daily life. One place where we routinely use our elbow and forearm is the seemingly simple act of turning a doorknob. We would likely need to flex our elbow to bring our hand up to the doorknob and then we would do supination of the forearm if we were turning the doorknob to the right. The [hand and wrist](https://3dmusclelab.com/hand-and-wrist-anatomy/) would be involved too, of course, in order to hold the doorknob and carry out our intended action of turning it. We also use our elbow and forearm just about every time we eat a meal. Unless we are eating a smoothie through a straw, we are using our elbow and forearm when we eat. We would flex the elbow to bring a fork or spoon up to our mouth and then use some amount of either pronation or supination to more finely position our hand holding the utensil as we bring the food to our mouth. We would reverse the process, extend the elbow and do some pronation or supination to bring our hand holding the utensil back down to our plate to get another bite of food. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Elbow and forearm movements in sports The elbow often gets mentioned in relation to both tennis and golf, as these sports are frequently associated with overuse injuries at the elbow joint. But, in this post, let’s just focus on what movements might be happening at the elbow joint in common actions within each of these sports. In a tennis overhead serve, for example, the elbow will flex to prepare and then rapidly extend as the player sends the racket towards the ball in the air. In a golf swing, we have a similar action. The golfer will need to flex the elbows to bring the golf club back and prepare to swing, then extend the forearms from the elbow to complete the swing. Obviously, the shoulder, as well as [the hand and wrist](https://3dmusclelab.com/hand-and-wrist-anatomy/) are all a part of this kinetic chain and are involved in each of these movements too. We’re just looking more closely here to see specifically what the elbow joint is doing in these actions. As you focus in more closely, you can see how actions that we usually take for granted, like turning a doorknob, are actually quite complex. You can try this for yourself as you do simple, routine actions during the day. Try asking yourself during these actions, what actions are my elbow and forearm doing? Do you want to learn more about the elbow and forearm? Check out these posts: [Exploring The Elbow Joint And Forearm](https://3dmusclelab.com/elbow-joint-and-forearm/) and [Elbow Overuse Injury: Golfer’s Elbow And Tennis Elbow](https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/lateral-hip-muscles-in-movement/ Author: David Keil · Updated: 2025-12-17 Movement # How Do The Lateral Hip Muscles Support The Actions Of Running And Cycling? ![Lateral Hip Muscles In Movement](https://3dmusclelab.com/wp-content/uploads/2020/10/lateral-hip-muscles-running.jpg) The lateral hip muscles ([gluteus medius, gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/), and [tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/)) are important muscles for movement in the body, but not in the way that we often think about muscles and movement. Instead of primarily creating movement in the way that we might expect of the quadriceps or the hamstrings, these three muscles are key to stabilization, which allows for controlled movement. We’ve already looked at these muscles individually in previous articles. Now, let’s take a look at how they contribute to movement using the examples of cycling and running. ## Where are the lateral hip muscles? Let’s do a quick review of what we mean by the lateral hip muscles. There are three muscles that we’re focusing on here, which often don’t get as much press as some of their larger cousins, but are equally as important. Gluteus medius and gluteus minimus both attach proximally at points on the external ilium and then attach distally to the greater trochanter of the femur. Gluteus minimus is located deep to the gluteus medius. They both contribute to abduction of the thigh at the hip and also have some fibers that assist with flexion, extension, and internal rotation of the hip. The lateral hip muscles also include [tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/), which attaches at the anterior iliac crest and then continues distally until it merges with the fibers of the iliotibial band, just below the greater trochanter. Like the lateral gluteals, tensor fascia latae can contribute to abduction of the hip. In addition to contracting to create an action, each of these muscles has a critical function in stabilization, which means preventing too much movement. [Gluteus medius, gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/), and [tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/) stabilize the hip joints. The tensor fascia latae also controls the tension in the iliotibial band, which in turn contributes to stabilization of the front and outside of the [knee joint](https://3dmusclelab.com/knee-joint/). Let’s take a closer look at how this stabilization function happens in the movements of cycling and running. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## The pedal stroke cycle in cycling In order to pedal a bicycle, muscles have to contract, of course. The full cycle of a pedal stroke is often described as having two phases. There is a power, or down stroke phase, when you’re pushing the pedal from the top to the bottom of the pedal stroke. The quadriceps, gluteus maximus, and the calf muscles are most actively contributing to this action. Then, there is a recovery phase or a pulling up action of the pedal, when we go from the bottom of the pedal stroke back to the top. The muscles that are most actively contributing to this action are the hamstrings, the hip flexors (such as the iliopsoas), and the muscles which dorsiflex the ankle (such as tibialis anterior and extensor digitalis longus). ## The lateral hip muscles in cycling The actual movements in the body are often more complicated and subtle than we give them credit for, however. In order to move one side of the lower body, it’s necessary for the body to brace and stabilize the other side. We shift weight subtly from one side to the other in order to move one leg and then the other, even when sitting as we would be on a bicycle. The muscles that do that key action of stabilization at the hip joints are the [gluteus medius, gluteus minimus](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/), and [tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/). Tensor fascia latae also controls the tension on the iliotibial band to help stabilize the [knee joint](https://3dmusclelab.com/knee-joint/) when we flex, extend, or rotate it. ## The gait cycle in running Similarly, as when cycling, there is a cycle of muscle activation when we’re running. There is a stance phase where one foot is on the ground and the other is behind you preparing to swing through. And, there is a swing phase, when the next foot swings through from behind to land in front of the body and take our weight. The main muscles used to create the action of running are the quadriceps, hamstrings, hip flexors, calf muscles, and gluteus maximus. ## The lateral hip muscles in running However, just as with cycling, the muscle activation to create a complicated movement like running is equally complex. In addition to the muscles we’ve mentioned that directly create the motion of running by flexing and straightening the knees and hip joints, the [lateral gluteals](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/) contribute to the rotation of the hips that’s needed for us to shift weight from one foot to the other. It’s also necessary for the body to brace and stabilize one side as we shift our weight from one side to the other. Again, the muscles that do that key action of stabilization at the hip joints are the [gluteus medius, gluteus minimus](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/), and [tensor fascia latae](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/), with tensor fascia latae also controlling the tension on the iliotibial band to help stabilize the [knee joint](https://3dmusclelab.com/knee-joint/). Specifically in running when we are bearing weight on one leg, the lateral hip muscles work to stabilize the hip on the opposite side. This allows us to then shift weight back to that side and swing the next leg through. ## Conclusion Our pelvis has two sides which move independently from one another. This is necessary for us to be able to walk or run, and even to pedal a bike. The fact that we have two sides of the pelvis interacting with one another means that the activity of muscles on one side of the pelvis affects what happens on the other side of the pelvis. This means that, although we certainly need muscles to create an action like running or cycling, stabilization is also just as important for walking, running, and riding a bike. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/shoulder-joint-in-movement/ Author: David Keil · Updated: 2025-12-17 Anatomical Applications # Let’s Break Down Some Real-life Shoulder Movements ![The Shoulder In Movement](https://3dmusclelab.com/wp-content/uploads/2019/11/shoulder-tennis.jpg) In the previous article, [What Is The Shoulder Girdle](https://3dmusclelab.com/shoulder-girdle/), we looked at the bones, joints, and basic movements of the shoulder girdle. But this only tells us so much about what’s happening at the shoulder joint in real-life movement. In this article we’ll cover what muscles attach to and move the shoulder joint, and we’ll apply that information to understanding movements of the shoulder in some daily life activities and common sports. To review: the shoulder joint is the ball and socket joint where the humerus (the upper arm bone) meets the depression in the scapula called the glenoid fossa. Its anatomical name is the glenohumeral joint. There are nine muscles that cross the glenohumeral joint, including: - Biceps brachii (long head) - Triceps brachii (long head) - Deltoid - Supraspinatus - Infraspinatus - Teres minor - Subscapularis - Teres major - Coracobrachialis There are a couple of other muscles that attach to and move the humerus, but don’t attach to the scapula, so they don’t technically cross the glenohumeral joint. However, they still contribute to moving the arm as part of the larger [shoulder complex](https://3dmusclelab.com/shoulder-girdle/). (Remember the whole shoulder complex includes muscles that go from the humerus to the scapula AND the muscles that go from the humerus to the clavicle and cross the acromioclavicular joint.) So, we could also include the following muscles in the group that move the shoulder joint: - Pectoralis major - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) If we group the muscles that move the shoulder by action we would have the following lists: Flexion of the shoulder: - Biceps brachii - Deltoid (anterior fibers) - Pectoralis major Extension of the shoulder: - Triceps brachii (long head) - Deltoid (posterior fibers) - [Teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - Teres minor - Infraspinatus Adduction of the shoulder: - Biceps brachii (short head) - Triceps brachii (long head) - [Teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - [Latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/) - Pectoralis major Abduction of the shoulder: - Deltoid - Supraspinatus Medial rotation of the shoulder: - Deltoid (anterior fibers) - Teres major - Latissimus dorsi - Pectoralis major - Subscapularis Lateral rotation of the shoulder: - Deltoid (posterior fibers) - Teres minor - Infraspinatus ## Shoulder movements in daily life So, now that we’ve reviewed the movements of the glenohumeral joint and the muscles that move the humerus, let’s apply our knowledge to a few situations from daily life. Remember though, as we highlight what the shoulder joint is doing in a particular activity, that real-life actions are complex and are almost always a combination of multiple actions at more than one joint. If you were closing a door by pulling it towards you, then you would be extending the shoulder joint. The muscles involved would include: triceps long head, deltoid (posterior fibers), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), and teres minor. If you were opening a door by pushing it away from you, then you would be flexing the shoulder joint. The muscles involved would include: biceps brachii, deltoid (anterior fibers), and pectoralis major ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Shoulder movements in sports Now let’s take a look at a couple of actions in tennis and some weight-lifting exercises you might do in the gym. If you were doing a forehand stroke with your racket in tennis, you would be doing horizontal flexion (also called horizontal adduction) and medial rotation at the shoulder. The muscles involved would include: pectoralis major, [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), subscapularis, and deltoid (anterior fibers). If you were doing a backhand swing with your racket in tennis, you would be doing horizontal extension (also called horizontal abduction) and lateral rotation at the shoulder joint. The muscles involved would include: teres minor, infraspinatus, and deltoid (posterior fibers). If you were watching shoulder movements in the gym, you might see lateral movements like abduction and adduction. If you did a dumbbell lateral raise, you would be abducting your arm at the shoulder. That is, you would raise your arm with the dumbbell laterally to 90 degrees. The muscles involved would include the deltoids and supraspinatus at the start of the movement. If you did a wide-grip pull-up you would be adducting your arms at the shoulder joints to pull yourself up to the bar. The muscles involved would include primarily: triceps brachii (long head), [teres major](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), [latissimus dorsi](https://3dmusclelab.com/latissimus-dorsi-and-teres-major/), and pectoralis major. As you look at shoulder movements in real-life actions you get an idea of how complex movement really is. If you want to challenge yourself to start applying anatomy, try this process for yourself. Take some real-life movements and see if you can break them down into their anatomical movements. Do you want to learn more about the shoulder? Check out our previous post, [What Is The Shoulder Girdle](https://3dmusclelab.com/shoulder-girdle/)? The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/planes-of-movement/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # Understanding The Planes Of Movement ![The Planes Of Movement](https://3dmusclelab.com/wp-content/uploads/2023/10/planes-of-movement.jpg) Human anatomy and kinesiology have a language just like any other area of study. Having terms to refer to bones, muscles, directions, and types of movement helps us be specific. It also helps us clearly communicate with other people about the body. That is especially true when talking about planes of movement because understanding simple aspects of movement makes it possible for us to better understand more [complex movement](https://3dmusclelab.com/functional-movement/). ## Why do we need planes of movement? The planes of movement help us describe actions that happen from [anatomical position](https://3dmusclelab.com/anatomical-position/). Remember that in anatomical position, we are standing upright with our arms by our sides, with our palms facing forward. Realistically, we don’t begin or end most activities from anatomical position. But even though it might be overly simplistic for describing real-life movement, it helps us establish our basic understanding of the directions of movement before diving into more complexity. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the planes of movement? There are three main planes of movement. They are described from anatomical position in a way that is similar to an x/y/z coordinate system on a graph. These are hypothetical, or imaginary lines in the body. They are not actual lines that you can see of course. ### Sagittal plane If you picture the body in anatomical position and then place a vertical line through the body which divides it into a right and left side, you are describing the sagittal plane. Movements of flexion and extension happen in this plane. For instance, sit-ups happen in the sagittal plane. In the sagittal plane, we have an additional term that refers more specifically to bisecting the body exactly through the midline. That’s referred to as the midsagittal plane. ### Frontal or coronal plane If you draw a vertical line through the body in anatomical position that divides the body into a front and back, then you are describing the frontal plane. That plane is also called the coronal plane. The movements that happen in that plane are abduction and adduction. Jumping jacks, for example, are a great example of a movement that happens in the frontal plane. ### Transverse or horizontal plane Finally, if you draw a horizontal line through the body that divides the body into a top and bottom section then you are describing the horizontal plane. That plane is also called the transverse plane. Rotational movements happen in that plane. Turning your head to look over your shoulder and [rotation of the spine](https://3dmusclelab.com/exploring-the-spine/) are examples of movements that happen in the transverse plane. ## Planes of movement in real life In real-life movement, we commonly move in more than one plane at once. If you pick just about any familiar movement, you can imagine this. For example, if you picture reaching above your head to get an item out of a cabinet, you are likely reaching at an oblique angle. So, rather than purely doing flexion and extension in the sagittal plane, you are actually doing some combination of flexion/extension and abduction/adduction. Those kinds of combinations better reflect real-life movements. This is sometimes referred to as moving in diagonal or oblique planes of movement. In order for movement to happen in the diagonal plane, the joint, or [joints](https://3dmusclelab.com/synovial-joint/), that are moving must be able to move in at least two of the planes already described. In addition to the example already given, a baseball pitch, a golf swing, kicking a football, and some [yoga postures](https://www.yoganatomy.com/bind-marichyasana-c-and-bound-twists/), all happen in the diagonal plane. However, if we experience pain, injury, weakness, tightness, or other sensations in our body, it can be helpful to break more complex actions down into simpler individual planes of movement. That has the potential to tell us something about how we might address what we’re experiencing if it is something we want to change. In even more complex and dynamic movements like [walking](https://3dmusclelab.com/what-is-the-gait-cycle/), we aren’t just moving a single joint through more than one plane at a time. We’re moving many joints through multiple planes simultaneously. So you can imagine it might be overwhelming to try to diagnose an issue with dysfunction or design a strength-training plan for everything all at once. This is where it can be helpful to break things down into parts. ## Conclusion There are three main planes of movement, the sagittal, frontal or coronal, and horizontal or transverse planes. These planes are hypothetical lines through the body, not physical lines that we can see. However, the concepts of these simple planes can be helpful for understanding more complex, multiplanar movements. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/functional-movement/ Author: David Keil · Updated: 2025-12-17 Movement # What Do We Mean By “Functional Movement?” ![What Is Functional Movement?](https://3dmusclelab.com/wp-content/uploads/2023/05/functional-movement.jpg) Buzzwords in the world of anatomy and [kinesiology](https://3dmusclelab.com/what-is-kinesiology/) come and go, just like any other area of study. Lately, I’ve been hearing more frequent references to the idea of “functional movement.” Interest in that subject comes from both those interested in physical fitness as well as those interested in rehabilitation of previous dysfunction. And as with understanding any new term, it can be helpful to gather some context for what we’re reading. In this article, we’ll take a look at some different perspectives on what we mean by that term. We’ll surround that with some modalities of different lineages that have all contributed to what we think about currently as functional movement. ## Defining functional movement Currently the simplest definitions of functional movement, often those used by trainers and athletic coaches, refer to those movements we need in order to function in daily life. That might include movements like squatting, lunging, and reaching among others. Functional movements are often described as whole-body movements in contrast to something like doing biceps curls at the gym, which focus on a single or a few [muscles](https://3dmusclelab.com/what-is-a-muscle/). Our daily movements may seem mundane, but biomechanically, they are actually quite complex. I would suggest that one of our most elemental movements is walking. And walking, or gait, is a very complex, but necessary series of movements. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Screening movement before dysfunction We don’t often think about the movements we need for accomplishing daily tasks until something is malfunctioning and/or causing us pain. Among the assessments, modalities, and training focused on functional movement is a common theme of evaluating how well we’re accomplishing these essential movements before we have significant pain and dysfunction. Those who focus on the concept of functional movement are also interested in what is needed for us to move with the greatest ease and efficiency, not just avoid pain. We may not all want to be elite athletes, but I imagine that we all want to experience as much ease as possible in our daily life. There are many things that impact our functional movement. Some of them aren’t things we can change, like our genetics. We have a particular bone shape and a range within which our particular body can get stronger or [more flexible](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/) in different ways. However, other things are more malleable like the patterns that result from our habits and activities. The modalities that focus on functional movement address the things that we can change with the aim to be as easeful in our movements as possible. ## Modalities of structure and movement There are many modalities that aim to affect our functional movement by changing how we relate to the patterns in our bodies. These modalities ask us to be curious about what makes us as functional as we can be. They emphasize understanding our relationship with gravity, and how our structure and postural patterns relate more or less easily with gravity in different ways. They also tend to look from the inside out with respect to where our relationship to foundational movements and their ease or difficulty comes from. One example of a modality that aims to enhance functional movement as well as overall health, is the area of osteopathy. Osteopathy aims to restore balance in the [myofascial continuities](https://3dmusclelab.com/what-is-connective-tissue/) in the body to support overall health including functional movement. Another example is the movement training system of Pilates. Named after its founder Joseph Pilates, it is intended to improve coordination and balance by refining how practitioners initiate movement from their core musculature. Similarly, Ida Rolf, known for her system of bodywork called structural integration (colloquially often called “Rolfing”), intended her system to balance the body’s [myofascial system](https://3dmusclelab.com/what-is-muscle-fascia/) and support ease of [posture](https://3dmusclelab.com/posture-and-smartphone/) and functional movement. The modality of Feldenkrais, named after it’s founder Moshe Feldenkrais, trains practitioners in efficiently doing essential movements like getting up from the floor or from a chair. ## Functional movement screen More recently, tools such as the Functional Movement Screen, created by Cook et al., ([Cook et al., 2006](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953313/) and [Cook et al., 2014](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4127517/)) have been created to identify where individuals lay within a range of what is considered “normal” for several essential movements. People who screen as outside that range for a particular movement can then seek further evaluation to see why that might be occurring and how it might be addressed. ## Conclusion Functional movements are those that are important in daily tasks. Understanding kinesiology and [how muscles work](https://3dmusclelab.com/muscle-contractions/) is essential for an understanding of why, when, and how a movement would be functional. It’s important to understand what we mean when we say functional movement, so that we’re also clear what we mean by dysfunction. There are many modalities that can help us screen for, assess, and improve our functional movements. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/what-is-kinesiology/ Author: David Keil · Updated: 2025-12-17 Movement # What is kinesiology? ![What is Kinesiology?](//3dmusclelab.com/wp-content/uploads/2018/05/kinesiology-running.jpg) Merriam-Webster defines kinesiology as: [the study of the principles of mechanics and anatomy in relation to human movement](https://www.merriam-webster.com/dictionary/kinesiology). We could define it more simply for our purposes as: the study of movement. Merriam-Webster also states, “As a field of research, kinesiology focuses particularly on the mechanics of muscular activity.” This is because we use muscles to create movement in our body. The 3D Muscle Lab, then, is a course on kinesiology, which is a fancy way to say it’s a course on muscles and how they create movement. ## Why would you want to know about how muscles create movement? First and foremost, we might be interested in kinesiology because this is a study of ourselves. We live in a body. Understanding something about how muscles create movement is important for a better understanding of our own functional movement or dysfunctional movement. You might be interested in how muscles create movement because you are training to become a bodyworker or a professional in a movement therapy field. If you are preparing to work as a massage therapist, a physical therapist, a personal trainer, or a yoga instructor, then understanding muscles will be an important part of your knowledge base. Your clients will have bodies too! Understanding your client’s functional or dysfunctional movement comes back to a clear understanding of how muscles initiate or restrict movement. Maybe you are a therapist working with clients already and you want to improve your effectiveness at supporting healthy movement for your clients. This definitely requires knowledge of how movement happens in the body. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What do you learn in a kinesiology course? The study of which muscles at which joints cause what kinds of movement are the details of kinesiology. Movement happens in the body at joints. A joint is where two bones come together. When one or more muscles contract and this results in changing the angle between two bones at a joint, then movement has occurred. Do you want to know which muscles cause the knee to bend? That’s kinesiology. What about which muscles cause the knee to straighten? That’s more kinesiology. Do you think we create the actions of bending and straightening the knee using the same or different muscles? The answers to these kinds of questions are the substance of a [kinesiology course](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/). The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/what-is-the-gait-cycle/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Is The Gait Cycle? ![Walking And The Gait Cycle](https://3dmusclelab.com/wp-content/uploads/2023/09/gait-cycle.jpg) The gait cycle is the technical name for how we walk. Walking is so fundamental to our daily activities that we often it for granted. But walking, or gait, requires a complex series of actions. Many books have been written on the gait cycle and the nitty gritty details are beyond the scope of this article. But it can be helpful to our understanding of how we do any kind of [functional movement](https://3dmusclelab.com/functional-movement/) to take a look at how we walk. So, in this article, I’ll give you a broad overview of what happens when we walk. ## Breaking down the gait cycle A gait cycle, also called a “full stride,” is composed of taking one step with each foot. It’s broken down into two main pieces. We are in the “stance” period when our striding food is connected with the ground. The “swing” period occurs when that foot is in the air. The brief moment when both feet are touching the ground is called the “double limb support” phase. Each of those subsections of a gait cycle can be broken down further. The stance phase begins with heel strike, then continues with weight-acceptance, followed by a mid-stance and then a late-stance phase. We spend about 60% of our gait cycle in the stance period. The swing period starts with toe-off and then continues through early swing, mid-swing, and late swing. We spend about 40% of our gait cycle in the swing phase. Let’s take a walk through the gait cycle to learn more about what happens during each of these phases. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Taking a walk A gait cycle technically begins with the heel strike. That’s the moment that the heel of our front foot meets the ground after we’ve swung that foot through. Then we shift our weight onto that leg (the weight-acceptance phase) and roll through our foot as we shift our body weight forward to complete the mid- and late-stance phases. During these portions of the stance phase, we pick our heel up and then our mid-foot as we shift our weight forward and roll through our foot. The momentum of our body going forward then brings us to toe-off on that same foot. That’s the moment that we lift our toes off the ground and our foot is in the air. We then swing that leg forward through the early, mid-, and late-swing phases to arrive back at heel strike when the heel of that same foot meets the ground again. ## Why is gait more complex than static posture? There are many forces that influence how we walk (and move in other ways too) that are less involved with maintaining our static posture. While gravity is active in both cases of course, during movement we also interact with momentum and something called the ground force reaction. This is the force created by the ground in response to our body contacting it. So, for example, when our foot hits the ground at heel strike, there is a force going down through our body into the ground created by our movement, and there is a reciprocal force that is generated by the ground in response that moves back up into our body. Additionally, we have skeletal, [muscular](https://3dmusclelab.com/what-is-a-muscle/), and [fascial](https://3dmusclelab.com/what-is-muscle-fascia/) ([connective tissue](https://3dmusclelab.com/what-is-connective-tissue/)) components that all come together to support a healthy gait. The ideal gait involves our whole body. While we might think of walking as something that mostly happens in our lower body, that isn’t really true. In fact, the more we involve the whole body, the more we can rely on the fascial spring loading of winding and unwinding, and the less muscular effort is necessary. In every plane, our body is pre-tensioning and then using that kinetic energy to move us forward. ## What is the body doing when we walk? ### Sagittal plane movement Our body is moving three-dimensionally, of course when we move. This also makes it more complicated to describe what our body is doing compared to describing static posture. If we start at the foot and work our way up the body, our first action is connecting our heel with the ground. Then we roll over the calcaneus (our heel bone), through the [ankle joint](https://3dmusclelab.com/exploring-the-ankle-joint/), through the forefoot, and then through the toes. We coordinate that with [knee](https://3dmusclelab.com/knee-joint/) extension, hip extension, and spinal extension to propel our body forward. As we roll through our foot from heel strike to toe-off, [our pelvis](https://3dmusclelab.com/exploring-the-pelvis/) on that side goes from a slight posterior tilt to a slight anterior tilt. On the other side, our pelvis does the opposite. As we swing our leg through, our pelvis on that side goes from a slight anterior tilt to a slight posterior tilt. Movement of both sides of our pelvis at the [sacroiliac joints](https://3dmusclelab.com/sacroiliac-joint/) allows this back-and-forth motion of the pelvis to happen as we walk. ### Frontal and transverse plane movement Along with our movement in the forward-backward sagittal plane, we also move in the frontal plane and rotate in the transverse plane to complete our walking pattern. As we step forward with one foot, meet the ground with our heel, and start to roll into our foot, our pelvis laterally tilts toward our weight-bearing leg, as we shift our weight from one leg to the other. And then as we take another step forward, our pelvis tilts laterally again in the other direction. To allow and stabilize the action of shifting our weight as we walk, we laterally flex our lumbar [spine](https://3dmusclelab.com/exploring-the-spine/) toward the weight-bearing leg. Our [abductors](https://3dmusclelab.com/lateral-hip-muscles-in-movement/) (our [lateral gluteals](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/)) then have to lengthen a bit in order to let that hip drop. At the same time, our [adductors](https://3dmusclelab.com/exploring-the-adductor-muscles/) on the other leg [engage](https://3dmusclelab.com/muscle-contractions/) as we lift the other side of our pelvis. As we step our foot forward, our pelvis also externally rotates and our upper thoracic spine and [shoulder girdle](https://3dmusclelab.com/shoulder-girdle/) counterrotate in the other direction. ## What influences our gait cycle? Since walking is so fundamental to many of our daily tasks, we might think that everyone just naturally learns to walk efficiently. But actually, there are lots of influences that alter our gait cycle. Initially, we learn to walk by modeling the people in our environment. Those people, our parents and other caregivers, almost certainly have their own gait pattern. And that pattern is influenced by genetics, including things like relative bone length, joint angles, flexibility, and other factors. It’s also moderated by activities that we do. What we do with our body creates patterns in it and walking is no exception to that. Repetitive work tasks, habits, and sports/leisure activities can also affect how we walk. ## What might disrupt our gait cycle? Injuries to the lower body will obviously have some effect on how we walk. Because gait itself is so complex, understanding the effects of injuries on walking is all the more complicated. Perhaps less obviously, injuries to the upper body also have the potential to affect how we walk, depending on the amount, duration, and type of compensations that we make to adapt to the injury. Surgical procedures like knee and hip replacements especially affect walking. The stability and function of the replaced joint may not be the same as the other side, creating altered walking patterns. ## Conclusion Walking is one of our most basic functional movements. We walk to complete many of our daily activities. The ability to walk is a foundation for many sports and leisure activities as well. While it is a complex multiplanar movement, understanding the gait cycle can help us better understand so many other types of movement. This fundamental series of movements is the base of much of the other movements we engage in. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## Resources Chaitow, L. and J. DeLany. 2011. Chapter 3: Gait analysis. *In* Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition). New York, NY: Churchill Livingstone Publishing. Earls, J. 2020. Born to Walk: Myofascial Efficiency and the Body in Movement. (Second Edition) Berkeley, CA: North Atlantic Books. [Hu, X., N. Zheng, W.-C. Hsu, J. Zhang, H. Li, Y. Chen, K. Dai, and T.-Y. Tsai. 2020. Adverse effects of total hip arthroplasty on the hip abductor and adductor muscle lengths and moment arms during gait. Journal of Orthopaedic Surgery and Research. 15:315-322.](https://pubmed.ncbi.nlm.nih.gov/32787875/) --- Source: https://3dmusclelab.com/what-happens-when-we-stretch-muscles/ Author: David Keil · Updated: 2025-12-17 Anatomy And Physiology # What Really Happens When We Stretch Our Muscles? ![What Is Stretching?](https://3dmusclelab.com/wp-content/uploads/2023/02/muscle-stretch.jpg) Stretching muscles is something that we often do without even thinking about it. You likely stretch a bit when you wake up in the morning or when you get up from sitting or standing in one position for a while. If you are involved in a sport, you might do specific stretches to help reduce tension or maintain range of motion in your body. But what happens, anatomically, when we stretch? In this article, we’ll look into what the research says about what might be happening in our body when we stretch. We’ll also take a look at why and how to stretch. ## What is stretching? Stretching, most generally, is lengthening [muscles](https://3dmusclelab.com/what-is-a-muscle/) with the intention of increasing range of motion. More specifically, there are several common kinds of stretching. Static stretching is something most people are familiar with. This is the simplest version where you reach and hold a shape for a few breaths or more, then release. There is also dynamic stretching, which describes stretching your muscle while moving. Another type is ballistic stretching, which involves adding a little bounce while trying to lengthen a muscle. And another type that has become more common is proprioceptive neuromuscular facilitation (PNF) technique. This type of stretching follows a protocol of alternating between stretching, then [isometrically contracting](https://3dmusclelab.com/muscle-contractions/) the muscles against resistance for a few seconds, then stretching again. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) These articles come from **3D Muscle Lab**, the 15-hour course that teaches 65 muscles in 3D. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Mechanisms The real answer to the question, what happens when we stretch muscles, is we don’t know. What’s most likely true is that we have more than one mechanism working together to create the end result of increased range of motion. Much of the research looking for mechanical changes from stretching has been inconclusive. One review study reported that muscle length changed after short-term stretching protocols, but the change in muscle length was temporary (Holzman Weppler and Magnusson, 2010). Other research has suggested that the mechanisms of change in [joint](https://3dmusclelab.com/synovial-joint/) range of motion after we stretch are actually based on sensation tolerance happening in our nervous system (Freitas et al., 2018; Holzman Weppler and Magnusson, 2010; Ben and Harvey, 2010). It’s possible that as our tolerance to stretch sensation increases so does our available range of motion. ## Why stretch? Regardless of how we do it, stretching is an effective way to increase range of motion. And maintaining a healthy range of motion is important for functional movement. If we do sports or athletic activities that build certain patterns of strength, maintaining a balance of flexibility is important for being able to access the strength that we have and for reducing the chances of injury. If we [sit a lot, at a desk](https://3dmusclelab.com/trapezius-computer-posture/), then we can benefit from stretching too. We can feel stiff as a result of both activity and inactivity. And, as we age, we all tend to get stiffer and dry out. Stretching can be helpful for ameliorating the effects of aging. We can’t avoid getting older, but we can do things like stretching to care for our bodies and slow the effects. A recent review study even found that stretching may have benefits for our cardiovascular system (Wong and Figueroa, 2019). ## How to stretch? Research suggests that all of the types of stretching effectively increase range of motion (Thomas et al., 2018). Some individual studies have found one particular type of stretching to be more effective than another type on a particular muscle group. For example, one review paper found that static stretching increased range of motion more than ballistic or PNF techniques (Thomas et al., 2018). But a different study found the opposite, that active stretching resulted in greater range of motion than static stretching (Meroni et al., 2010). So, it’s hard to generalize from these studies. It may be that different muscle groups respond differently to types of stretching. As far as the effectiveness of stretching on range of motion, frequency seems to matter more than the style or technique of stretching. A recent review paper reported that weekly frequency of stretching was positively related to range of motion (Thomas et al., 2018). As the frequency of weekly increased, the range of motion gains increased as well. They did not find a relationship between duration of an individual session of stretching and gains in range of motion (Thomas et al., 2018). ## Conclusion Stretching is something that usually feels good and is good for us! Regardless of which type of stretching we choose to do, it’s likely going to be effective at increasing our range of motion. And it may have other positive effects throughout our body. These are good reasons to add some stretching to your movement routine. The course ## Learn all 65 muscles in 3D, one lesson at a time. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Ben, M. and L.A. Harvey, 2010. Regular stretch does not increase muscle extensibility: a randomized controlled trial. Scandinavian Journal of Medicine and Science in Sports. 20:136-144.](https://pubmed.ncbi.nlm.nih.gov/19497032/) [Freitas, S. R., B. Mendes, G. Le Sant, R.J. Andrade, A. Nordez, Z. Milanovic. 2018. Can chronic stretching change the muscle-tendon mechanical properties? A review. Journal of Medicine and Science in Sports. 28:794-806.](https://pubmed.ncbi.nlm.nih.gov/28801950/) [Holzman Weppler, C. and S.P. Magnusson. 2010. Increasing muscle extensibility: A matter of increasing length or modifying sensation? Physical Therapy. 90(3):438-449.](https://pubmed.ncbi.nlm.nih.gov/20075147/) [Meroni, R., C.G, Cerri, C. Lanzarini, G. Barindelli, G.D. Morte, V. Gessaga, G.C. Cesana, and G. de Vito. 2010. Comparison of active stretching technique and static stretching technique on hamstring flexibility. Clinical Journal of Sports Medicine. 20(1):8-14.](https://pubmed.ncbi.nlm.nih.gov/20051728/) [Thomas, E., A. Bianco, A. Paoli, A. Palma. 2018. The relation between stretching typology and stretching duration: The effects on range of motion. International Journal of Sports Medicine. 39:243-254.](https://pubmed.ncbi.nlm.nih.gov/29506306/) [Wong, A. and A. Figueroa. 2019. Effects of acute stretching exercise and training on heart rate variability: A review. Journal of Strength and Conditioning Research. 35(5):1459-1466.](https://pubmed.ncbi.nlm.nih.gov/30789584/) --- Source: https://3dmusclelab.com/anatomy-of-the-hamstrings/ Author: David Keil · Updated: 2026-09-11 Muscle reference · Thigh # Anatomy And Function Of The Hamstrings The "true" hamstrings include three separate muscles: semitendinosus, the semimembranosus, and the long head of biceps femoris. What distinguishes these muscles from other muscles or portions of muscles that function alongside them, is that the hamstrings cross both the knee and hip joints. ![Hamstrings](https://3dmusclelab.com/wp-content/uploads/2022/08/hamstring-muscles.jpg) The hamstrings are muscles that just about everyone is at least somewhat familiar with. If you’re someone with tight hamstrings, then you might think you are very familiar with exactly where those hamstrings are located. But the hamstrings are much more than just something to stretch out in yoga. They’re necessary for fundamental movements like walking and running. And understanding the anatomy of the hamstrings can help us understand how they function. In this article, we’ll dig a little deeper into the anatomy and function of the hamstrings. [Try a free hamstring lesson here](https://3dmusclelab.com/free-hamstring-lesson/) ## Quick facts Origin · Insertion · Action - **Origin**: **Biceps femoris (long head):** ischial tuberosity of the pelvis (sit bone) **Semitendinosus:** ischial tuberosity of the pelvis (sit bone) **Semimembranosus:** ischial tuberosity of the pelvis (sit bone) - **Insertion**: **Biceps femoris (long head):** head (top) of the fibula **Semitendinosus:** pes anserine, an area of the tibia near the tibial tuberosity **Semimembranosus:** posterior medial condyle of the tibia (the inside and top part of the back of the tibia) - **Action**: **Biceps femoris (long head):** posterior tilt of the pelvis, extend the thigh at the hip joint, flex the knee, lateral rotation of the knee when it's flexed **Semitendinosus:** posterior tilt of the pelvis, extend the thigh at the hip joint, flex the knee, medial rotation of the knee when it's flexed **Semimembranosus:** posterior tilt of the pelvis, extend the thigh at the hip joint, flex the knee, medial rotation of the knee when it's flexed ## Which muscles make up this group? The “true” hamstrings include three separate muscles: semitendinosus, the semimembranosus, and the long head of biceps femoris. What distinguishes these muscles from other muscles or portions of muscles that function alongside them, is that the hamstrings cross both [the knee](https://3dmusclelab.com/knee-joint/) and hip joints. Biceps femoris actually has a second “head”, or section of the muscle. But it only crosses and affects the knee joint, as we’ll see below. So, it is not considered a true hamstring. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Where are the hamstrings located? The specific location of each of these muscles ultimately tells us something about what they can do. All three of the hamstrings (biceps femoris long head, semimembranosus, and semitendinosus) attach to ischial tuberosity of the pelvis (sit bone) at their proximal end. From there, they each take a different path. The long head of biceps femoris takes the lateral path. It’s the cord-like muscle we can easily feel just above the back of our knee. It attaches at its distal end onto the head (top) of the fibula (the smaller of our lower leg bones). Our other two hamstrings take a medial path from their proximal attachment at the sit bone. Both semimembranosus and semitendinosus run down the medial side of the back of our thigh. Semitendinosus then attaches at its distal end on the pes anserine, which is an area of the tibia near the tibial tuberosity. Semimembranosus attaches at its distal end on the posterior medial condyle of the tibia (the inside and top part of the back of the tibia). ## Why does understanding the hamstrings’ anatomy help us understand movement? The hamstrings are not one muscle. They are three separate muscles that work together in some of their actions. But during other functions, some of the individual muscles do different actions from one another. If all three of the hamstrings attach to the sit bones on the pelvis, then it makes sense that they could work together to move the pelvis. And this turns out to be true, unsurprisingly. All three of these muscles can contribute to pulling [the pelvis](https://3dmusclelab.com/exploring-the-pelvis/) into more of a posterior tilt. Likewise, all three hamstrings function to extend the thigh at the hip joint and to flex the knee. But in other movements, the actions of the individual hamstring muscles diverge. Remember that we have two hamstrings (semimembranosus and semitendinosus) which attach more towards the medial side of our lower leg. So these two muscles contribute to medial rotation of the knee when it’s flexed. In contrast, biceps femoris attaches on the lateral side of the lower leg. As you might guess, it contributes to the lateral rotation of the knee when it’s flexed. ## Functional movement In sports, we might start to think of our hamstrings as just those tight muscles which restrict our movement. But they are so much more than that! The specific action that we mentioned above, extension of the thigh at the hip, is a critical part of walking. When we are walking, the hamstring muscles on one side assist with that movement by pulling the thigh back, a little bit like loading a spring. Other muscles can then take over to bring our leg from behind us into our next step. The hamstrings then contribute eccentrically by slowing down the swing of that leg just before we place our foot. That the hamstrings also attach at the knee has an implication in gait, or walking, too. They contribute to flexing the knee as we pick up our foot so we can swing it through for our next step. The short head of biceps femoris pitches in and works with the true hamstring muscles during this action. ## No muscle works alone One thing that’s important to understand about muscles and their actions though, is that no muscle works alone! Muscles work together to create or resist an action. One or more of the hamstrings [work as synergists](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) with other muscles in all of their functions. In the action of pulling the thigh back before we take a step, all three hamstrings are working with gluteus maximus, which is actually our most powerful hip extensor. [Adductor magnus](https://3dmusclelab.com/adductor-magnus-muscle/), which also attaches to the sit bone, contributes to the hip extension as well. Sartorius, gracilis, popliteus, and gastrocnemius all work along with the hamstrings when we flex the knee. ## What can anatomy tell us about how to effectively stretch our hamstrings? As I said above, one of the actions of all three hamstring muscles is to posteriorly tilt the pelvis on the hip joints. So let’s think about that. If you are actively using your hamstrings in a seated forward bend—maybe because they are just short and tight from sports and you find it difficult to relax them—how easy do you think it will be to stretch them? Probably, not so easy, right? So, if this is you, then it might be helpful to find a way to place the pelvis in a more neutral position before you try to stretch those hamstrings. You might do that by sitting up on a yoga block or bolster. ## Why can anatomy help us understand how to work with hamstring pain? I’ve covered this question in more detail in other articles, so I’ll just touch on it here. Anatomy can tell us a lot about [how a muscle functions](https://3dmusclelab.com/what-is-a-muscle/). And it can tell us something about how and why a muscle might be dysfunctional. In the case of the three hamstrings, remember that we said that they cross both the hip and knee joints. This means that the tension on both the hip and knee joints influences what we feel in the hamstrings. So whether we’re feeling pain at the sit bone end of these muscles, or pain at the distal end below the knee, it’s important to take a look at what’s happening at the other end of the muscle when we try to find the cause of the pain. The hamstrings are important muscles in functional movement like walking. Understanding their anatomy helps us understand more fully how they function. And, understanding the anatomy of the hamstrings, can help us understand why they might be dysfunctional. Now that you have a better understanding of hamstring anatomy, take that information with you next time you go for a walk and see what you notice. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/brachialis-and-coracobrachialis-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Upper arm # Brachialis And Coracobrachialis Muscles Brachialis and coracobrachialis are found in the anterior compartment of the arm along with biceps brachii. Coracobrachialis is on the medial side of this group. Brachialis is deeper inside this group of muscles; it’s deep to the biceps brachii. ![Brachialis and Coracobrachialis Muscles](https://3dmusclelab.com/wp-content/uploads/2025/10/brachialis-coraco.jpg) We can turn our arms and place our [hands](https://3dmusclelab.com/hand-and-wrist-anatomy/) in a multitude of positions. All of the muscles that move our arms collectively make that possible. Among all the arm muscles, you’re probably already somewhat familiar with the [biceps and triceps](https://3dmusclelab.com/biceps-and-triceps/). But, have you heard of brachialis and coracobrachialis? In this article, we’ll take a closer look at two additional arm flexors, the brachialis and coracobrachialis. Read on to find out what important movements we need these [muscles](https://3dmusclelab.com/muscles-when-we-age/) to do. ## Quick facts Origin · Insertion · Action · Innervation - **Origin**: **Brachialis:** distal anterior humerus **Coracobrachialis:** coracoid process of the scapula; some fibers merge with the tendon of biceps brachii short head - **Insertion**: **Brachialis:** coronoid process and the ulnar tuberosity **Coracobrachialis:** shaft of the humerus - **Action**: **Brachialis:** flexion of the forearm at the elbow (primary mover) **Coracobrachialis:** adduction of the arm at the shoulder joint, assists flexion of the arm at the shoulder, assists stabilizing the head of the humerus in the shoulder socket - **Innervation**: **Coracobrachialis:** musculocutaneous nerve ## Location: The other anterior arm muscles Brachialis and coracobrachialis are found in the anterior compartment of the arm along with biceps brachii, which I wrote about previously. The anterior compartment includes the group of muscles on the front of the arm. Coracobrachialis is on the [medial](https://3dmusclelab.com/anatomical-terms-location-position/) side of this group. The attachment of its proximal tendon is superficial to (on top of) the tendon of the short head of the biceps brachii. It then runs medial to brachialis and biceps brachii. Brachialis is deeper inside this group of muscles in the anterior compartment of the arm. It’s deep to the biceps brachii. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments When we talk about muscle attachments, it’s important to remember that anatomy texts and articles that you read report what’s most common. As with many muscles, there is some variation from person to person in the specific muscle attachments for these two muscles. It’s hard to know the extent of that variation, as most of that knowledge comes from cadaver dissection. Specific muscle attachments are often a difficult, and in some cases impossible, thing to see in live humans. ### Brachialis Most commonly, brachialis attaches proximally to the distal anterior humerus. Distally, it generally attaches to the coronoid process and the [ulnar tuberosity](https://3dmusclelab.com/elbow-joint-and-forearm/). Researchers have seen variation in the particular structure of this muscle across the population in cadaver dissection. While it’s generally described as having a single muscle belly, in less common variations, it has two muscle bellies. ### Coracobrachialis Generally, the coracobrachialis attaches proximally to the coracoid process of the scapula. Additionally, some researchers report that some fibers merge with the [tendon](https://3dmusclelab.com/ligaments-and-tendons/) of biceps brachii short head. Distally, this muscle attaches to the shaft of the humerus. More recent studies of coracobrachialis have found that one common variation of this [muscle](https://3dmusclelab.com/what-is-a-muscle/) includes two muscle bellies, rather than one, with the more superficial and deep parts of this muscle penetrated by the musculocutaneous nerve (the nerve that innervates this muscle). Other less common variations have three or even four muscle bellies. ## Muscle actions ### Brachialis The primary action of the brachialis muscle is [flexion](https://3dmusclelab.com/anatomical-terms-for-movements/) of the [forearm at the elbow](https://3dmusclelab.com/elbow-and-forearm-in-movement/). This is often surprising to people. Many people think it’s the biceps brachii that primarily does this action. While the biceps brachii assists in flexion of the forearm, the brachialis is the primary mover in that [action](https://3dmusclelab.com/muscle-origin-insertion-and-action/). ### Coracobrachialis The primary action of the coracobrachialis is adduction of the arm at the [shoulder joint](https://3dmusclelab.com/shoulder-girdle/). Remember that adduction is bringing something closer to the midline. So, adduction of the arm is bringing the arm into the side of the body. Coracobrachialis assists with flexion of the arm at the [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/). It can also assist in stabilizing the head of the humerus in the shoulder socket. ## Conclusion As with most [joints](https://3dmusclelab.com/synovial-joint/) in our body, multiple [muscles work together](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) to create movement at the shoulder and elbow joints. Flexion of the forearm at the elbow is primarily initiated by brachialis. Arm adduction is the primary action of coracobrachialis. However, both of these muscles assist with additional actions. Coracobrachialis can assist the biceps brachii with flexion of the arm at the shoulder. Biceps brachii assists brachialis with flexion of the forearm at the elbow. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Nasr A.Y. and R.A. Youssef. 2024. Morphological classification, anatomical variations, innervation patterns, musculocutaneous nerve relation of the coracobrachialis muscle: anatomical study and clinical significance. Anatomy and Cell Biology Journal. 57(2):194-203.](https://pubmed.ncbi.nlm.nih.gov/38735653/) [Plantz, M.A., B. Bordoni. 2023. Anatomy, Shoulder and Upper Limb, Brachialis Muscle. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551630/](https://www.ncbi.nlm.nih.gov/books/NBK551630/) [Triantafyllou G., K. Natsis, G.P. Georgiev, C. Koutserimpas, L. Olewnik, G. Tsakotos, N. Zielinska, and M. Piagkou. 2024. The coracobrachialis muscle: typical morphology, accessory forms, and the issues with terminology. Surgical and Radiological Anatomy. 46(1):81-84.](https://pubmed.ncbi.nlm.nih.gov/37934299/) [Zielinska, N., F. Duparc, M. Polguj, A. Borowski, and L. Olewnik. 2022. A proposal for a new classification of the Coracobrachialis longus: A rare case or a new, distinct muscle? Annals of Anatomy – Anatomischer Anzeiger. 239:151825.](https://www.sciencedirect.com/science/article/pii/S0940960221001515) --- Source: https://3dmusclelab.com/gluteus-medius-gluteus-minimus/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # What Are The Lateral Gluteals? The gluteus medius and gluteus minimus muscles actually overlap one another along the lateral side of our pelvis. The gluteus minimus muscle is the smaller of the two and is deep to the larger gluteus medius muscle that lays over the top of it. ![Gluteus Medius And Gluteus Minimus](https://3dmusclelab.com/wp-content/uploads/2020/10/minimus-medius.jpg) While you might already be familiar with the large gluteus maximus (the superficial “butt” muscle), we actually have three gluteal muscles on each side of our pelvis. In this article we’ll take a look at the lesser known, but definitely equally important, gluteus medius and gluteus minimus muscles. ## Quick facts Origin · Insertion · Action - **Origin**: **Gluteus medius:** external ilium and iliac crest, between the anterior and posterior gluteal lines **Gluteus minimus:** between the anterior and inferior gluteal lines of the external ilium, from the ASIS to the iliac tubercle - **Insertion**: **Gluteus medius:** greater trochanter of the femur **Gluteus minimus:** greater trochanter of the femur - **Action**: **Gluteus medius:** stabilization, especially during walking and running, but also when standing; anterior portion contributes to the rotation in the pelvis when we walk **Gluteus minimus:** stabilization, especially during walking and running, but also when standing ## Where are gluteus medius and gluteus minimus? The gluteus medius and gluteus minimus muscles actually overlap one another along the lateral side of our pelvis. The gluteus minimus muscle is the smaller of the two and is deep to the larger gluteus medius muscle that lays over the top of it. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments ### Gluteus medius The gluteus medius attaches proximally to the external ilium and iliac crest. More specifically, the gluteus medius attaches between the anterior and posterior gluteal lines. The gluteal lines are small raised, almost bumpy, bony lines or ridges of the external ilium. Distally, the gluteus medius attaches to the greater trochanter of the femur. ### Gluteus minimus Proximally, the gluteus minimus attaches between the anterior and inferior gluteal lines of the external ilium. The attachment extends from the anterior superior iliac spine (ASIS) to the iliac tubercle. Distally, like the gluteus medius, the gluteus minimus attaches to the greater trochanter of the femur. ## Muscle actions The lateral gluteal muscles are often labeled as “abductors”. But how often do we actually do movement that requires abducting our leg? The key action of the lateral gluteals is actually stabilization, especially during walking and running, but also when standing. Additionally, these lateral gluteal muscles have sections of fibers that contribute to or assist other muscles with other movements. Research suggests that gluteus medius is composed of either three (Semciw et al., 2013; Al-Hayani, 2009) or four (Flack et al., 2014) different subsections based on fiber direction and innervation. It is composed of at least an anterior, middle, and posterior subsection. Gluteus minimus is composed of two subsections of fibers, an anterior and a posterior section (Al-Hayani, 2009). Each of these subsections of gluteus medius and gluteus minimus is fed by their own nerves, so they can fire independently of one another. The subsections of gluteus medius and gluteus minimus each fire at different times to stabilize the pelvis and to contribute to the cycle of actions that happens when we walk, called the gait cycle. The anterior portion of gluteus medius also contributes to the rotation that happens in the pelvis when we walk (Al-Hayani, 2009). One group of researchers found that the posterior segments of gluteus medius were active when we need to propel the leg from an extended position when walking, while the anterior segments were active during the parts of the walking action where we need to flex and internally rotate our leg (Anders et al., 2017). Gluteus medius and gluteus minimus are important muscles in the body which make it possible for us to stand, walk, and run. If you’d like to know more about other structures that support those actions, check out our related posts in this series: [Tensor Fascia Latae And The Iliotibial Band](https://3dmusclelab.com/iliotibial-band-syndrome/), [Iliotibial Band Syndrome](https://3dmusclelab.com/iliotibial-band-syndrome/), and [The Lateral Hip Muscles In Running And Cycling](https://3dmusclelab.com/lateral-hip-muscles-in-movement/). The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Al-Hayani, A. 2009. The functional anatomy of hip abductors. Folia Morphologica. 68(2):98-103.](https://pubmed.ncbi.nlm.nih.gov/19449297/) [Anders, C., S. Patenge, K. Sander, F. Layher, U. Biedermann, and R.W. Kinne. 2017. Detailed spatial characterization of superficial hip muscle activation during walking: A multi-electrode surface EMG investigation of the gluteal region in healthy older adults. June 5. 24pgs. https://doi.org/10.1371/journal.pone.0178957](https://pubmed.ncbi.nlm.nih.gov/28582456/) [Flack, N.A.M.S., H.D. Nicholson, and S.J. Woodley. 2014. The anatomy of the hip abductor muscles. Clinical Anatomy. 27:241-253.](https://pubmed.ncbi.nlm.nih.gov/23625344/) [Semciw, A.I., T. Pizzari, G.S. Murley, and R.A. Green. 2013. Gluteus medius: An intramuscular EMG investigation of anterior, middle and posterior segments during gait. Journal of Electromyography and Kinesiology. 23:858-864.](https://pubmed.ncbi.nlm.nih.gov/23587766/) --- Source: https://3dmusclelab.com/tensor-fascia-latae-and-it-band/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # What Is Tensor Fascia Latae And What Is The Iliotibial Band? The tensor fascia latae is a muscle on the lateral, or outside, of your hip. The iliotibial band is not actually a muscle. It’s three layers of ligamentous fascia: a more superficial layer, an intermediate layer, and a deep layer. ![Tensor Fascia Latae And The Iliotibial Band](https://3dmusclelab.com/wp-content/uploads/2020/10/tfl-itband.jpg) If you stand, walk, or run, the tensor fascia latae and iliotibial band (IT band) are critical structures for making that possible. In this article we’ll take a look at where these structures are, what they do, and how they work in conjunction with one another to make walking and running possible. The tensor fascia latae is a muscle on the lateral, or outside, of your hip. The iliotibial band is not actually a muscle. It’s three layers of ligamentous fascia: a more superficial layer, an intermediate layer, and a deep layer. Its general function is to help maintain stability of the hip-to-knee-joint relationship when we put weight into our legs. It is often discussed alongside the tensor fascia latae because the tensor fascia latae, along with the gluteus maximus, controls the amount of tension in the IT band. Let’s explore these structures in more detail. ## Quick facts Origin · Insertion · Action - **Origin**: **Tensor fascia latae:** anterior iliac crest **Iliotibial band:** fibers of the tensor fascia latae, the gluteus maximus, and the gluteal aponeurosis - **Insertion**: **Tensor fascia latae:** fused with the fibers of the iliotibial band, generally just below the greater trochanter **Iliotibial band:** distal linea aspera, lateral epicondyle of the femur, patella/patellofemoral ligament, Gerdy’s tubercle - **Action**: **Tensor fascia latae:** stabilizes the opposite hip from the one bearing weight when walking, running, or standing; affects the amount of tension in the IT band **Iliotibial band:** stabilizes the hip and especially the knee joint when weight-bearing, helps distribute the load ## Where is the tensor fascia latae and where is the IT band? Both of these interrelated structures are located along the lateral side of the hip. The iliotibial band runs from the lateral hip along the lateral side of the leg all the way down until it crosses the knee joint. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments ### Tensor fascia latae The tensor fascia latae attaches proximally to the anterior iliac crest. Distally, it becomes fused with the fibers of the iliotibial band, generally just below the greater trochanter, but there is some variability from person to person with respect to the point at which the fusion of these structures occurs (Flack et al., 2012). ### Iliotibial band The iliotibial band is interwoven with multiple attachments at both ends. Based on its name you could guess that it attaches to both the ilium and the tibia, which is true. More specifically, the IT band arises at the proximal end from fibers of the tensor fascia latae, the gluteus maximus, and the gluteal aponeurosis (a fibrous layer of fascia between the iliac crest and the gluteus maximus). Along its path, the iliotibial band attaches to the linea aspera, a linear area of rough textured bone on the femur that serves as an attachment site for several muscles. At its distal end, the iliotibial band attaches to: the distal linea aspera of the femur, the lateral epicondyle of the femur, the patella/patellofemoral ligament, and an area on the lateral tibia called Gerdy’s tubercle. ## Muscle actions ### Tensor fascia latae The tensor fascia latae is sometimes grouped with the [gluteus medius and gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/) as a hip abductor muscle. However, its primary action is to stabilize the opposite hip from the one that is actually bearing weight, or that we are standing on, when walking, running, or standing. When it contracts it also affects the amount of tension in the IT band, and in that way, indirectly affects the stabilization of the knee. ### Iliotibial band The iliotibial band is a critically important structure for stabilizing the hip, and especially the knee joint, when we load weight into these joints. It functions to stabilize the joints and help distribute the load when we are weight-bearing in one or both legs, like we would be when standing, walking, or running, for example. Because of its location, the iliotibial band works in conjunction with the anterior cruciate ligament (ACL) to stabilize particularly the lateral and anterior sides of the knee joint. The muscles into which the iliotibial band attaches at its proximal end, the tensor fascia latae and the gluteus maximus, influence the amount of shortness or tension that the IT band has. Simultaneous contraction of the lateral quadricep muscle, the vastus lateralis which runs laterally alongside the IT band, can also contribute to increasing the tension of the IT band. The tensor fascia latae and the iliotibial band are critical structures in the body for making it possible for us to stand, walk, and run. If you’d like to know more about what structures support those actions, check out our related posts in this series: [The Gluteus Medius And Gluteus Minimus Muscles](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/), [Iliotibial Band Syndrome](https://3dmusclelab.com/iliotibial-band-syndrome/), and [The Lateral Hip Muscles In Running And Cycling](https://3dmusclelab.com/lateral-hip-muscles-in-movement/). The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References [Al-Hayani, A. 2009. The functional anatomy of hip abductors. Folia Morphologica. 68(2):98-103.](https://pubmed.ncbi.nlm.nih.gov/19449297/) [Flack, N.A.M.S, H.D. Nicholson., and S.J. Woodley. 2012. A review of the anatomy of the hip abductor muscles, gluteus medius, gluteus minimus, and tensor fascia lata. Clinical Anatomy. 25:697-708.](https://pubmed.ncbi.nlm.nih.gov/23625344/) --- Source: https://3dmusclelab.com/exploring-the-adductor-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Thigh # Exploring The Adductor Muscles The adductors are a group of five muscles that are important for stabilizing and balancing our pelvis when we're standing, walking, and running. As a group, the adductors weave together to form a fan of muscles on the medial part of the thigh between the quadriceps on the front and the hamstrings on the back. ![Adductor Muscles](https://3dmusclelab.com/wp-content/uploads/2022/12/adductor-anatomy.jpg) The adductors are a group of five muscles that are important for stabilizing and balancing our pelvis when we’re standing, walking, and running. We previously covered the largest muscle in this group: [adductor magnus](https://3dmusclelab.com/adductor-magnus-muscle/). In this article, we’ll take a look at the four other adductor muscles. ## Quick facts Origin · Insertion · Action - **Origin**: **Pectineus:** superior pubic ramus **Adductor brevis:** inferior pubic ramus **Adductor longus:** pubic ramus, just laterally to the pubic symphysis **Gracilis:** inferior pubic ramus - **Insertion**: **Pectineus:** pectineal line, a bony ridge along the femur from the lesser trochanter to the linea aspera **Adductor brevis:** upper third of the linea aspera **Adductor longus:** middle third of the linea aspera of the femur **Gracilis:** pes anserine of the tibia - **Action**: **Pectineus:** adduction of the thigh at the hip, flexion of the thigh at the hip **Adductor brevis:** adduction of the thigh at the hip, flexion of the thigh at the hip, medial rotation of the thigh at the hip (depending on position) **Adductor longus:** adduction of the thigh at the hip, flexion of the thigh at the hip, medial rotation of the thigh at the hip (depending on position) **Gracilis:** adduction of the thigh at the hip, flexing the knee when the knee is straight, medial rotation of the lower leg at the knee joint ## What are the adductor muscles? This is a large group of muscles in our thigh. If we include adductor magnus, this group covers about a quarter of the volume of space taken up by muscles in our thigh (Watanabe et al., 2009). The five muscles of the adductor group are: pectineus, adductor brevis, adductor longus, gracilis, and as I mentioned above, adductor magnus. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Where are the adductor muscles? ### Muscle attachments As a group, the adductors weave together to form a fan of muscles on the medial part of the thigh between the quadriceps on the front and the hamstrings on the back. They attach at their superior end to various places along the medial, and posterior aspects of the [pubic bone](https://3dmusclelab.com/exploring-the-pelvis/). With the exception of gracilis, each of these muscles attaches at their inferior end to a different point along a bony ridge on the back of the femur called the linea aspera. As you’ll see below, gracilis is the longest in this muscle group. It goes all the way to the tibia before it attaches at its inferior end. Let’s look at each of these [muscle’s attachments](https://3dmusclelab.com/muscle-origin-insertion-and-action/) more specifically. Pectineus attaches superiorly to the superior pubic ramus and inferiorly to the pectineal line. The pectineal line is a bony ridge that extends along the femur from the lesser trochanter to the linea aspera. Adductor brevis attaches superiorly to the inferior pubic ramus and inferiorly to the upper third of the linea aspera. Adductor longus attaches superiorly to the pubic ramus, just laterally to the pubic symphysis. Inferiorly, it attaches to the middle third of the linea aspera of the femur. Finally, gracilis attaches superiorly to the inferior pubic ramus. It’s unique among the adductors in that it is the only one of the group to cross two joints: the hip joint and the knee joint. This is because its inferior attachment is at the pes anserine of the tibia. ## Muscle actions As a group, all of the adductor muscles contribute to adduction of the thigh at the hip. Additionally, adductor longus, adductor brevis, and pectineus also assist with flexion of the thigh at the hip. Adductor longus and Adductor brevis can assist with medial rotation of the thigh at the hip as well, depending on the position that we’re in. Finally, gracilis, as I said, is the only one of this muscle group to cross the knee joint and the hip joint. So, it can also assist with flexing the knee when the knee is straight and with medial rotation of the [lower leg](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) at the [knee joint](https://3dmusclelab.com/knee-hyperextension/). It may not be obvious when we do adduction of the thigh at the hip in everyday movements. It’s important to remember that muscles don’t just [function to create movement](https://3dmusclelab.com/muscle-contractions/), they also function to control movement. Walking is an example where adduction is a necessary part of a chain of actions to control our movement. While we might not think of adduction right away as part of how we walk, it is part of the connected series of actions in walking. During walking, the adductors’ main action is to work in relation to their antagonists (the abductors) to help stabilize each side of the pelvis as we take a step. The adductors also work in relation to the abductors of each hip to help stabilize our pelvis when we are in a simple standing position. ## Conclusion Although they sometimes get overlooked when we give our attention to our more dynamic thigh muscles like the quadriceps or [hamstrings](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/), the adductor muscles are an important group to know. They have a key role in assisting those more dynamic muscles in their actions. They are also critical to maintaining a balanced posture in our lower body in stillness and in movement. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. Delany. 2011. Chapter 11: The Pelvis. In: Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body. (Second Edition). Churchill Livingstone Elsevier. New York, NY. Travell, J.G and D.G. Simons, 1993. Chapter 13: Pectineus Muscle and Chapter 15: Adductor Muscles of the Hip. In: Myofascial Pain and Dysfunction- The Trigger Point Manual. Vol. 2 – The Lower Extremities. Lippincott, Williams, and Wilkins Philadelphia, PA. [Watanabe, K., K. Katayama, K. Ishida, and H. Akima. 2009. Electromyographic analysis of hip adductor muscles during incremental fatiguing pedaling exercise. European Journal of Applied Physiology. 106:815-825.](https://pubmed.ncbi.nlm.nih.gov/19466446/) --- Source: https://3dmusclelab.com/tibialis-anterior-fibularis-longus/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Lower leg # Exploring Tibialis Anterior And Fibularis Longus: The Leg Stirrup Tibialis anterior is an important muscle in the anterior compartment, the front of the leg. You'll find fibularis longus in the lateral compartment, or the outside of the leg. These two muscles are both important for walking, jogging, and running, as well as jumping and kicking. ![Tibialis Anterior And Fibularis Longus](https://3dmusclelab.com/wp-content/uploads/2022/08/anatomical-stirrup.jpg) In this article, we’ll explore two muscles found in the leg: tibialis anterior and fibularis longus. These two muscles are both important for walking, jogging, and running, as well as jumping and kicking. Keep reading to learn more about their attachments and actions. ## Quick facts Origin · Insertion · Action - **Origin**: - **Insertion**: **Tibialis anterior:** medial cuneiform and the base of the first metatarsal **Fibularis longus:** medial cuneiform and the base of the first metatarsal - **Action**: **Tibialis anterior:** dorsiflexion and inversion of the foot at the ankle, pulls the body over the foot when the foot is fixed **Fibularis longus:** plantarflexion and eversion of the foot at the ankle ## Where are the tibialis anterior and fibularis longus? Generally, you’ll find these two muscles in the leg. Tibialis anterior is an important muscle in the anterior compartment, the front of the leg. You’ll find fibularis longus in the lateral compartment, or the outside of the leg. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments Specifically, tibialis anterior’s [origin](https://3dmusclelab.com/origin-insertion-and-action/), or proximal attachment, is on the lateral shaft of the upper ⅔ of the tibia (larger of the two lower leg bones) and the lateral condyle of the tibia. Distally, it attaches onto the medial cuneiform and the base of the first metatarsal. Fibularis longus attaches proximally to the lateral shaft of the upper ⅔ of the fibula (smaller of the two lower leg bones) and the head of the fibula. Distally, it attaches to the medial cuneiform and the base of the first metatarsal. It meets the distal attachment of tibialis anterior there. ## Muscle actions These two muscles do [opposite actions](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/). Specifically, tibialis anterior does dorsiflexion and inversion of the foot at the ankle. And if the foot is in a fixed position, like when we’re standing on it, tibialis anterior helps to pull our body over our foot. In contrast, fibularis longus does plantarflexion and eversion of the foot at the ankle. What’s as important as naming the individual actions of these two muscles, is how they work together. ## Muscular dynamics These two muscles work together to form the stirrup of the foot. That means they work together to manage the balance between eversion and inversion of our foot. Particularly when we’re walking over uneven surfaces, these two muscles work together to stabilize the ankle joint. Remember that what we refer to as the ankle joint is really more than one [bone-to-bone connection](https://3dmusclelab.com/synovial-joint/). The tibiotalar joint (also called the talocrural joint) is where the distal end of the tibia (the larger of the two lower leg bones) meets the talus bone. The talus bone is the bone that sits between the distal end of the tibia and the calcaneus (heel bone). The talocalcaneal joint (also called the subtalar joint) is where the talus bone meets the calcaneus. ## The gait cycle Along with the other muscles of the leg, ankle, and foot, these two muscles both play an important role in our gait cycle. Our gait cycle starts when the heel of one foot hits the ground and we roll through the foot as the bottom of the foot makes full contact with the ground. (When our foot is on the ground it’s called the stance phase.) When we roll through our foot, however, we don’t roll straight back to forward. There is actually a small amount of inversion followed by eversion of our ankle. Both the tibialis anterior and fibularis longus help control this shift in motion. As we’re lowering our foot to the ground, tibialis anterior is [eccentrically contracted](https://3dmusclelab.com/muscle-contractions/), helping us to lower our foot in a controlled way. When our foot is on the ground, it helps stabilize our ankle joint and assists with pulling our body over our foot. As we get ready to take our next step, we shift our weight forward over the toes of that foot. When we press our toes to the ground to pick up our foot, the tibialis anterior does dorsiflexion of the ankle. (When our foot is in the air it’s called the swing phase.) That dorsiflexion, while our foot is in the air, helps keep us from stubbing our toes on the ground as we swing our foot through and place it back on the ground, completing our step. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Chaitow, L. and J. DeLany. 2011. Chapter 14: The Leg and Foot. In Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body (Second Edition). [Ludwig, O., J.Kelm, M.Frohlich. 2016. The influence of insoles with a peroneal pressure point on the electromyographic activity of tibialis anterior and peroneus longus during gait. Journal of Foot and Ankle Research. 9,33. https://doi.org/10.1186/s13047-016-0162-5](https://pubmed.ncbi.nlm.nih.gov/27555883/) Travell, J.G. and D.G. Simons. 1993. Chapter 19: Tibialis Anterior Muscle and Chapter 20: Peroneal Muscles. In Myofascial Pain and Dysfunction—The Trigger Point Manual. Volume 2. --- Source: https://3dmusclelab.com/iliopsoas-muscle-anatomy/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # Exploring The Iliopsoas Muscle Iliopsoas is among the deepest layer of our muscles, with psoas major running along the lumbar spine. Iliacus and psoas major are frequently grouped together as the “iliopsoas” because they share a common attachment and they work together to do the same primary movement. The iliopsoas is the strongest hip flexor. ![Iliopsoas: Iliacus and Psoas Major Muscle](https://3dmusclelab.com/wp-content/uploads/2019/01/iliacus-psoas.jpg) The core of our body isn’t necessarily what we might think it is. While there are many different ways to understand our core, one is considering the layers of muscles and fascia that make up our structure. In that sense we’re talking about superficial versus deep. Superficial muscles are those closest to our outer surface, like the rectus femoris in our quadriceps for example. Underneath that muscle, or deep to it in anatomical language, we find other muscles. Iliopsoas is among the deepest layer of our muscles, with psoas major running along the lumbar spine. Muscles that are found in this deepest layer are a key part of functional movement in our body. Read on for an introduction to one of these core muscles. ## Quick facts Origin · Insertion · Action - **Origin**: **Iliacus:** fossa of the anterior ilium **Psoas major:** body of the vertebrae from T12 to L5 - **Insertion**: **Iliacus:** lesser trochanter of the femur, via a common tendon with psoas major **Psoas major:** lesser trochanter of the femur, via a common tendon with iliacus - **Action**: **Iliacus:** flexes the hip joint, flexes and externally rotates the femur **Psoas major:** flexes the hip joint, external rotation of the hip joint, adduction of the hip joint ## Some key facts - The iliopsoas is a key postural and structural muscle. - It is the primary muscle that connects our torso to our legs. - The iliopsoas is the strongest hip flexor. - It is the primary muscle responsible for an important movement: walking. - It is intimately related to the convergence of tissues and structures often referred to as “the core.” - It spans more joints in the body than any other muscle. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What is the iliopsoas muscle? Iliopsoas could be associated with two different muscles: iliacus and psoas major. Iliacus and psoas major are frequently grouped together as the “iliopsoas” because they share a common attachment and they work together to do the same primary movement. Some people also have a psoas minor muscle. However, the psoas minor is a fairly insignificant muscle that is absent in approximately half of the population. When it is present, it contributes to different actions than psoas major and iliacus. Additionally, psoas minor is not particularly relevant to movement because it is a small, thin muscle. So, psoas minor is not usually included as part of the iliopsoas. Instead when we say that, we are referring to just iliacus and psoas major. ## Where are these muscles located? The proximal end of iliacus originates on the fossa of the anterior ilium. This is the broad area on the inside of the pelvic bowl. The proximal end of psoas major originates on the body of the vertebrae from T12 to L5. Psoas major has a long path from its proximal end to its distal end where it meets up with iliacus. It runs down the sides of the spine, anteriorly over the front of the pubic bone, and then heads posteriorly to meet up with the iliacus. Along its path, psoas major crosses nine joints: T12–L1, L1–L2, L2–L3, L3–L4, L4–L5, L5–sacrum, sacrum–ilium (SI joint), pubic symphysis, and the hip joint. When the iliacus and psoas major join fibers at their distal ends, they form a common tendon and insert on the lesser trochanter of the femur. For those who have a psoas minor, it’s found anterior to (in front of) the psoas major. It’s a thin muscle even in those who have one, unlike the iliacus and psoas major. The psoas minor attaches at its proximal end onto the bodies of T12 and L1. At its distal end, it attaches onto the pubis. ## What actions does the iliopsoas do? Iliacus flexes and externally rotates the femur. Both iliacus and psoas major flex the hip joint. This is their primary action. Psoas major can also contribute to external rotation of the hip joint and adduction of the hip joint. Remember, actions can go origin to insertion or insertion to origin. Iliopsoas is the strongest hip flexor, whether this means we are standing and bringing the leg to the torso or we are sitting on the floor and bringing the torso towards the legs. ## Want to learn more? Check out these related articles: - [How To Contact Your Iliopsoas](https://3dmusclelab.com/contact-your-iliopsoas-muscle/) - [Iliopsoas And Movement](https://3dmusclelab.com/iliopsoas-and-movement/) - [Iliopsoas And Back Pain](https://3dmusclelab.com/how-iliopsoas-might-be-related-to-your-back-pain/) - [The Psoas Muscle: Ultimate Guide](https://www.yoganatomy.com/psoas-muscle-ultimate-guide/) (for yoga practitioners) The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/gluteus-maximus/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # Maximizing Your Gluteus Maximus: The Powerhouse Behind Every Step! The gluteus maximus is a large superficial muscle with broad attachments. Typically the gluteus maximus is the largest muscle in the body. Some anatomists divide the muscle into superior (upper) and inferior (lower) fibers. ![Gluteus Maximus Powers You Uphill](https://3dmusclelab.com/wp-content/uploads/2024/09/gluteus-maximus-stairs.jpg) Everyone is familiar with the gluteus maximus. It’s your butt muscle, the one you’re probably sitting on right now. But as with so many aspects of our anatomy, this familiar muscle is much more complex than we often think. In this article, we’ll take a look at the different parts of this important [muscle](https://3dmusclelab.com/what-is-a-muscle/), learn where they attach, and explore how we use this muscle in movement. ## Quick facts Origin · Insertion · Action - **Origin**: Posterior iliac crest (some superior fibers merge with the thoracolumbar fascia), lateral side of the sacrum and coccyx, and the sacrotuberous ligament - **Insertion**: **Superior fibers:** gluteal tuberosity, a rough bony ridge on the posterior femur just below the greater trochanter **Inferior fibers:** iliotibial band (IT band) - **Action**: **All fibers:** hip extension, lateral rotation and abduction of the thigh at the hip, posteriorly rotating the pelvis on the thigh (when standing on the leg) **Inferior fibers:** also adduction of the thigh at the hip ## Muscle attachments Typically the gluteus maximus is the largest muscle in the body, so it has a broad area of attachments. Some anatomists divide the muscle into superior (upper) and inferior (lower) fibers because attachment locations and fiber direction impact which actions certain areas of the muscle can contribute to. All portions of this muscle are superficial. Muscles that are deep to (underneath) the gluteus maximus include the [deep six lateral rotators](https://3dmusclelab.com/deep-six-lateral-rotators-movement/), [gluteus minimus](https://3dmusclelab.com/gluteus-medius-gluteus-minimus/), and most of the [gluteus medius](https://3dmusclelab.com/lateral-hip-muscles-in-movement/). The attachments considered the origin of this muscle span an area from the iliac crest all the way to the coccyx. On the superior end of this muscle, those attachments start around the posterior iliac crest, although some superior fibers may also merge with the thoracolumbar fascia. Gluteus maximus fibers then attach all along the lateral side of the sacrum and coccyx, and finally, some fibers merge with the sacrotuberous ligament. From their point of origin, the fibers of gluteus maximus run in a slightly oblique direction. They attach at two main points that are considered the insertion for this muscle. The more superior fibers insert onto the gluteal tuberosity, a rough bony ridge on the posterior femur just below the greater trochanter. The more inferior fibers insert into the [iliotibial band (IT band)](https://3dmusclelab.com/tensor-fascia-latae-and-it-band/). ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle actions The [primary action](https://3dmusclelab.com/muscle-contractions/) of gluteus maximus is hip extension. It’s a large muscle, so it can contribute lots of power to the action of hip extension when that’s needed. Additionally, all fibers of gluteus maximus can contribute to lateral rotation and abduction of the thigh at the hip. Because of where they attach, the inferior fibers can also assist with adduction of the thigh at the [hip](https://3dmusclelab.com/exploring-the-hip-joint/). Finally, it’s important to remember that the [action of a muscle](https://3dmusclelab.com/abdominal-muscles/) can change if we fix what is often considered the more moveable bone where that muscle is attached. In the case of gluteus maximus, if we’re standing on the leg, so the thigh is held in place, then this muscle can contribute to posteriorly rotating the [pelvis](https://3dmusclelab.com/exploring-the-pelvis/) on the thigh. ![Glutes alt text](https://3dmusclelab.com/wp-content/uploads/2018/04/gluteus-maximus-muscle.png) ### Providing power One of the key roles of the gluteus maximus muscle is supplying power. In [functional movement](https://3dmusclelab.com/functional-movement/), this muscle is an important part of powering through activities like running, walking up stairs, or hiking uphill. In situations like running or hill climbing, our other hip extensors, our hamstrings, are less powerful. This is because the [hamstrings](https://3dmusclelab.com/anatomy-of-the-hamstrings/) cross the knee joint in addition to the hip joint, and in running or hill climbing, the knee is bent. So in these situations, gluteus maximus provides a lot of our power for dynamic hip extension. ### Supporting balance Gluteus maximus is engaged at a much lower level in less intense activities like regular walking or standing. However, through its attachment into the thoracolumbar fascia which then merges with the contralateral latissimus dorsi, the action of gluteus maximus can affect the balance of cross-body tension that affects our gait. This is because in [gait](https://3dmusclelab.com/what-is-the-gait-cycle/), the contralateral arm swings forward when the opposite leg steps forward. ### Keeping us upright Finally, gluteus maximus is also part of helping us move into an upright position. Posturally, we use gluteus maximus in sitting to help us stay upright. Its action as a hip extensor helps [balance out the activity](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) of the hip flexors on the opposite side of our pelvis. In functional movement, we also use this muscle when we move to a standing position from a seated or a bent-over position. ## Conclusion The gluteus maximus is a large superficial muscle with broad attachments. It’s active to some degree in walking and standing. However, its primary role is to provide powerful hip extension when we need it to climb stairs, hike uphill, or run. It also supports us posturally when sitting and transitioning from a seated into a standing position. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 12: The Hip. In Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body (Second Edition). New York, NY: Churchill Livingstone Publishing. [Biel, A. 2005. Chapter 6: Pelvis and Thigh. In Trail Guide to the Body. (Third Edition.) Boulder, CO: Books of Discovery Publishing.](https://booksofdiscovery.com/product/trail-guide-to-the-body/) [Elzanie, A. and J. Borger. [Updated 2023 Apr 1]. Anatomy, bony pelvis and lower limb, gluteus maximus muscle. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538193/](https://www.ncbi.nlm.nih.gov/books/NBK538193/) --- Source: https://3dmusclelab.com/neck-muscles-superficial/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Neck # Neck Muscles: The Superficial And Mid-layers Our neck muscles support and move our head allowing us to point our eyes in different directions and do things like nodding yes and no. The muscular layers surrounding the cervical spine help protect the spinal column and viscera in the throat. ![Neck Muscles](https://3dmusclelab.com/wp-content/uploads/2024/03/neck-muscles.jpg) Our neck has many [critical functions](https://3dmusclelab.com/functional-movement/) and it’s the muscles that surround our cervical spine that support its [movement](https://3dmusclelab.com/planes-of-movement/), stability, and protective functions. Our neck muscles support and move our head allowing us to point our eyes in different directions and do things like nodding yes and no. The muscular layers surrounding the cervical spine help protect the spinal column and viscera in the throat. They cross the nerves of the [brachial plexus](https://3dmusclelab.com/brachial-plexus/). Our neck muscles even support our breathing process. In part one of this two-part article series, we’ll take a look at the attachments and actions of the superficial and mid-layer neck muscles to better understand how our neck functions. ## Quick facts Origin · Insertion · Action - **Origin**: **Upper trapezius:** base of the occiput, the ligamentum nuchae, and the spinous processes of C1-C7 **Sternocleidomastoid:** manubrium of the sternum and the medial portion of the clavicle **Levator scapulae:** transverse processes of C1-C4 **Anterior scalene:** transverse processes of C3-C6 **Middle scalene:** transverse processes of C2-C7 **Posterior scalene:** transverse processes of C4-C6 **Splenius capitis:** spinous processes of C7-T3 and the nuchal ligament **Splenius cervicis:** spinous processes of T3-T6 - **Insertion**: **Upper trapezius:** lateral portion of the clavicle and the acromion process of the scapula **Sternocleidomastoid:** mastoid process **Levator scapulae:** superior angle and superior aspect of the medial border of the scapula **Anterior scalene:** first rib **Middle scalene:** first rib **Posterior scalene:** second rib **Splenius capitis:** mastoid process and the occipital bone **Splenius cervicis:** transverse processes of C1-C3 - **Action**: **Upper trapezius:** elevates the scapula, extension of the neck, lateral flexion, contralateral rotation of the head (unilateral) **Sternocleidomastoid:** flex the neck (bilateral), same-side lateral flexion and opposite-side rotation of the head (unilateral), assists forced inhalation **Levator scapulae:** lifts the scapula, downwardly rotates the scapula, extension and lateral flexion of the neck (scapula stabilized) **Scalenes:** laterally flex the neck, assist a little in flexing the neck (bilateral), lift the first or second ribs **Splenius capitis and cervicis:** extension of the neck, lateral flexion of the neck, ipsilateral rotation ## Superficial and mid-layer muscles in the neck - Trapezius - Sternocleidomastoid - Levator scapulae - Anterior scalenes - Middle scalenes - Posterior scalenes - Splenius capitis - Splenius cervicis ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments It’s important to point out that there is variation from person to person in the points of attachment ([origin and insertion](https://3dmusclelab.com/muscle-origin-insertion-and-action/)) for all of these muscles. The broader the area of attachment, the more potential for variability in individuals. Additionally, most of our neck muscles exist as pairs. Most of our neck muscles are arranged with one on the right side and one that is a mirror image on the left side of our neck. So when we describe attachments of neck muscles imagine each muscle or set of muscles that I describe as part of a pair. ### Trapezius – cervical portion The [trapezius](https://3dmusclelab.com/trapezius-muscle/) is a large superficial muscle that covers much of our back. It’s commonly divided into several sections as the fibers of each section run in a different direction and influence different movements. The muscle as a whole has attachments from the head and neck to the shoulders to the spine. Since our focus in this article is the neck, let’s take a look at just the cervical portion of the trapezius. The superior attachments of the upper trapezius include the base of the occiput, the ligamentum nuchae, and the spinous processes of C1-C7. At its inferior end, the upper trapezius inserts onto the lateral portion of the clavicle and the acromion process of the [scapula](https://3dmusclelab.com/scapula/). ### Sternocleidomastoid At its inferior end, the sternocleidomastoid has two portions or heads. One of those inserts onto the manubrium of the sternum, a small bony projection on each side of the top of the breastbone. The other head of sternocleidomastoid (SCM) attaches on the medial portion of the clavicle (collarbone). Both heads of SCM then travel up towards our head and merge together to form one band of muscle. At its superior end, SCM attaches on the mastoid process, a bony knob just behind our ear. ### Levator scapulae The levator scapulae muscle is interwoven with the upper trapezius. It has a more superficial portion at the superior end and a deeper portion at the inferior end. It attaches superiorly to the transverse processes of C1-C4. Then, as it travels down, a portion of this [muscle](https://3dmusclelab.com/what-is-muscle-fascia/) weaves under the upper trapezius. At its inferior end, levator scapulae attaches to the superior angle and superior aspect of the medial border of the scapula. ### Scalenes We have three scalene muscles on each side of our neck. We have anterior scalenes, middle scalenes, and posterior scalenes. All of the scalenes attach onto transverse processes (TPs) of the cervical vertebrae at their superior end. The anterior scalenes attach to the TPs of C3-C6. The middle scalenes attach to the TPs of C2-C7. The posterior scalenes attach to the TPs of C4-C6. At their inferior ends, all of the scalenes attach onto the ribs. The anterior and middle scalenes attach onto the first rib. The posterior scalenes attach to the second rib. ### Splenius capitis and cervicis We have two splenius muscles on the right and left sides of our posterior neck. We have a splenius capitis and splenius cervicis. At its inferior end, splenius capitis attaches to the spinous processes (SPs) of C7-T3 and the nuchal ligament. At its superior end splenius capitis attaches to the mastoid process and the occipital bone. Splenius cervicis attaches at its inferior end on the SPs of T3-T6. At its superior end, splenius cervicis attaches to the TPs of C1-C3. ## Muscle actions in movement and posture Our neck is very mobile in all planes and easily does flexion, extension, lateral flexion (side-to-side motion), and rotation. It’s our neck muscles which are arranged in interwoven layers, that create these movements and simultaneously meet our need for [stabilizing the head on our neck](https://3dmusclelab.com/posture-and-smartphone/). As you know from my past articles, muscles do multiple types of actions. They do concentric contractions to create an action, eccentric contractions to lengthen while contracting, and isometric contractions to maintain a level of tension. Our neck muscles do all of these [types of contractions](https://3dmusclelab.com/muscle-contractions/). Our neck is an important part of our body for both [initiating movement and maintaining posture](https://www.yoganatomy.com/move-hips-or-neck-during-twisting-poses/). Our neck muscles work together to do both of those important actions. It’s also important to keep in mind as we talk about muscle actions in the neck, that as I said earlier in this article, most neck muscles exist in right-left pairs. For that reason, many neck muscles do one set of actions when the two sides of the pair work together (bilaterally), and different actions when only one side of the pair is engaged (unilateral action). However, it’s also useful to remember that if one side of a paired neck muscle is concentrically contracting to create an action unilaterally, then the other side of that same muscle is in a lengthened position. Let’s take a look at the specific contributions of each [muscle](https://3dmusclelab.com/what-is-a-muscle/). ### Trapezius – cervical portion Broadly, when all the sections of the muscle work together, our trapezius acts on our scapula. More specifically to the neck, the [upper trapezius](https://3dmusclelab.com/trapezius-computer-posture/) elevates the scapula. It can also assist with extension of the neck and lateral flexion. When one side of the upper trapezius contracts, it can also contribute to rotation of the head to the side opposite of the side that’s contracting (contralateral rotation). ### Sternocleidomastoid When the SCM muscles work together (bilaterally), they flex the neck. When one side of the SCM muscles contracts, it can contribute to lateral flexion to the same side and rotation of the head to the opposite side, just like the cervical portion of the trapezius we discussed above. ### Splenius capitis and cervicis Since both splenius capitis and splenius cervicis are located on the posterior side of the neck, they work together to do extension of the neck. They also both do lateral flexion of the neck along with the upper trapezius and SCM we’ve already mentioned. However, unlike the SCM and upper trapezius, both splenius muscles contribute to rotation of the neck to the same side as they are contracting on (ipsilateral rotation). ### Scalenes Remember that as I mentioned earlier, we have three scalene muscles on each side of our neck, the anterior scalenes, the middle scalenes, and the posterior scalenes. All three of the scalenes work together to laterally flex our neck. When the scalenes on both sides of the neck work together, they can assist a little bit in flexing the neck, although they’re not well-positioned to contribute too significantly to that action. They can also lift the first or second ribs. This becomes especially important in breathing. Read on for more about the neck muscles in breathing below. ### Levator scapulae Along with the upper trapezius, levator scapulae does what its name suggests, it lifts the scapula. It can also downwardly rotate the scapula. But it’s important to remember that a muscle can create an action from either direction depending on which of the bones it attaches to is stabilized. So, if we stabilize our scapula, then levator scapulae moves the head towards the scapula by doing extension of the neck. With the scapula stabilized, levator scapulae can also assist with lateral flexion of the neck along with many of the muscles we’ve discussed in this article. ## Neck muscles in breathing Although we might think of the diaphragm as our breathing muscle, many neck muscles are also important in aspects of breathing. Because they have attachments on the upper ribs, sternum, or other portions of our chest, some of our neck muscles help expand the space in our ribcage. That’s particularly true for situations where we need a little extra breath, like when we’re exercising. The neck muscles that support our breathing in those situations are called secondary respiratory muscles. If we think of our diaphragm as the primary muscle of respiration, then the neck muscles (and some other muscles) that help out when we need more breath than in passive relaxed breathing, are considered secondary respiratory muscles. SCM is one pair of these muscles that support breathing. Because the inferior portions of SCM attach to the clavicle and sternum, it can assist in forced inhalation. Forced inhalation is the name for the more active type of breathing action we do when exercising. The scalenes are another pair of neck muscles that support our breathing. Because they attach to either the first or second rib, they can help lift the ribcage and make more space when we’re breathing hard. ## Conclusion Our neck muscles are involved in the important actions of both moving and supporting our head in space. Some neck muscles also support the critical action of breathing when we need extra breath. In this article, we’ve covered the attachments and actions of the superficial and mid-layer neck muscles. Read part two of this two-part series, to learn more about the deep neck muscles. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/adductor-magnus-muscle/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Thigh # What And Where Is The Adductor Magnus Muscle? The adductor magnus is a large muscle on the inside of the thigh that could more accurately be described as multiple muscle sections (usually described as two to four sections). Although each of the muscle sections can contribute to different movements, sometimes even opposite movements, the sections are all considered to be one muscle. ![Adductor Magnus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/adductor-magnus-mus.jpeg) The adductor magnus is a large muscle on the inside of the thigh that could more accurately be described as multiple muscle sections (usually described as two to four sections). There is some debate about how many sections are most often present and there is some variability from person to person regarding how many distinct sections are present. In this post we’ll describe the two main sections. Although each of the muscle sections can contribute to different movements, sometimes even opposite movements, the sections are all considered to be one muscle. ## Quick facts Origin · Insertion · Action - **Origin**: **Proximal section:** inferior pubic ramus **Distal section:** ischial tuberosity and ischial ramus - **Insertion**: **Proximal section:** upper part of the linea aspera of the femur **Distal section:** lower part of the linea aspera along the femur and the adductor tubercle - **Action**: **Proximal section:** adduction of the thigh at the hip, extension of the hip joint, some small amount of external rotation of the thigh **Distal section:** adduction of the thigh at the hip, extension of the hip joint, internal rotation of the thigh ## Where is the adductor magnus muscle located? The adductor magnus muscle is located on the inside of the thigh and has a large area of attachment from the pubic bone and ischium continuing down most of the femur. Portions of the adductor magnus are deep to a number of other muscles, including two of the other adductor muscles: pectineus and adductor longus. ### Origin The more proximal section of the adductor magnus muscle is also the most anterior of the sections. It attaches proximally to the inferior pubic ramus. The more distal section of the adductor magnus muscle attaches proximally to the ischial tuberosity and to the ischial ramus. ### Insertion The more proximal section of the adductor magnus muscle attaches distally to the upper part of the linea aspera of the femur. The more distal section of the adductor magnus attaches distally to the lower part of the linea aspera along the femur and to the adductor tubercle. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What actions does the adductor magnus muscle do? There is still some debate among researchers about what actions each section of the adductor magnus muscle does. As the technology that is used to study muscle activity continues to advance, researchers learn more. The most current research suggests that the proximal and distal sections of the adductor magnus muscle have some actions in common, but can also contribute to actions unique to each section. When in [anatomical position](https://3dmusclelab.com/anatomical-position/) both sections of the adductor magnus can contribute to adduction of the thigh at the hip and extension of the hip joint. When it comes to rotation however, the muscle sections differ in their actions. The proximal section of the adductor magnus muscle can contribute to at least some small amount of external rotation of the thigh, but the distal section of the adductor magnus muscle contributes to internal rotation of the thigh. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Benn, M.L., T. Pizzari, L. Rath, K. Tucker, and A. I. Semciw 2018. Adductor magnus: An EMG investigation into proximal and distal portions and direction specific action. Clinical Anatomy. 31:535–543. Travell, J.G. and D.G. Simons. 1993. Adductor Muscles of the Hip. *In* Myofascial Pain and Dysfunction —The Trigger Point Manual. Volume 2. --- Source: https://3dmusclelab.com/biceps-and-triceps/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Upper arm # The Biceps and Triceps Muscles: Forearm Movers Two of the key muscles for moving the forearm are the biceps brachii and triceps brachii. The biceps brachii is located in the anterior compartment (front) of the arm along with brachialis and coracobrachialis. The triceps brachii is located in the posterior compartment (back) of the arm. ![Biceps brachii and triceps brachii](https://3dmusclelab.com/wp-content/uploads/2025/09/biceps-triceps.jpg) The muscles that move our forearms are essential for all the [functional movements](https://3dmusclelab.com/functional-movement/) we do that require placing our hands in a position to grasp something. That includes activities like driving a car because, of course, we have to grasp the steering wheel. It also includes fine motor activities like writing and typing. Placing our hands in a particular position is the job of the [shoulder](https://3dmusclelab.com/shoulder-girdle/) and arm, but especially the job of the elbow and forearm. Two of the key muscles for moving the forearm are the biceps brachii and triceps brachii. In this article, we’ll look at these two muscles. Read on to learn where they attach, what they do, and how they relate to each other. ## Quick facts Origin · Insertion · Action - **Origin**: **Biceps long head:** supraglenoid tubercle of the scapula **Biceps short head:** coracoid process of the scapula **Triceps long head:** infraglenoid tubercle of the scapula **Triceps lateral head:** humerus, superior to (above) the radial groove **Triceps medial head:** humerus, inferior to (below) the radial groove - **Insertion**: **Biceps brachii:** radial tuberosity, merging into the fascia of the forearm **Triceps brachii:** olecranon process of the ulna - **Action**: **Biceps brachii:** supination of the forearm, assists flexion of the forearm at the elbow, assists flexion of the arm at the shoulder **Biceps long head:** helps stabilize the shoulder joint **Triceps brachii:** extension of the forearm at the elbow **Triceps long head:** assists extension and adduction of the arm at the shoulder joint, stabilizing the shoulder **Triceps lateral head:** stabilizes the elbow joint in extension ## The biceps and triceps relationship While there are several muscles that cross the elbow joint to move the forearm, in this article, I focus on the biceps brachii and triceps brachii. That’s because, in addition to being key movers of the forearm, they are [antagonists](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/). That means that they are always acting in relation to each other. As we look at the attachments and actions of [muscles](https://3dmusclelab.com/what-is-a-muscle/), it’s important to remember that no muscle works alone. When we apply [kinesiology concepts](https://3dmusclelab.com/what-is-kinesiology/) to functional movement, we’re never seeing just one muscle. We’re seeing the relationship of tension and direction of all the muscles that surround and act on a particular joint. Keep that in mind as we look closer at the biceps brachii and triceps brachii. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Locations ### Biceps brachii The biceps brachii is located in the anterior compartment (front) of the arm along with brachialis and coracobrachialis. This muscle typically has two muscle bellies, called heads. The muscle name describes this. Bi means two, and cep means heads. However, there is some variation in the number of muscle bellies among the larger population. A very small percentage of people have more than two heads in the biceps muscle. The two heads of biceps are referred to as the long head and the short head. ### Triceps brachii The triceps brachii is in some ways the mirror image of the biceps brachii. It’s located in the posterior compartment (back) of the arm. As you might guess from the name, it typically has three muscle bellies, or heads. Tri means three, and as I said already, cep means head. As with the biceps brachii, there is some variation in that, however. A very small percentage of people have more than three heads in the triceps muscle. The three heads of triceps are called the long head, lateral head, and medial head. ## Muscle attachments ### Biceps brachii The two heads of the biceps brachii both [attach proximally](https://3dmusclelab.com/muscle-origin-insertion-and-action/) to the scapula, but they attach to separate places. Farther down, they merge together into a single tendon at the distal end. Proximally, the long head of biceps attaches to the supraglenoid tubercle of the scapula. The short head attaches proximally to the coracoid process of the scapula. After the long head and short head merge into a single [tendon](https://3dmusclelab.com/ligaments-and-tendons/), it attaches distally onto the radial tuberosity and merges into the [fascia](https://3dmusclelab.com/what-is-muscle-fascia/) of the forearm. ### Triceps brachii Like the biceps brachii, each of the three triceps brachii heads attaches to a separate place at the proximal end. One head, the long head, attaches to a place on the [scapula](https://3dmusclelab.com/scapula/) called the infraglenoid tubercle. The other two heads attach to the humerus (upper arm bone). The lateral head attaches proximally to the humerus, superior to (above) a depression in the bone called the radial groove. The medial head attaches proximally to the humerus, inferior to (below) the radial groove. Although they originate proximally in three separate locations, the three heads of triceps brachii combine into a single tendon distally. It attaches to the olecranon process of the ulna (the smaller of the two forearm bones). ## Muscle actions ### Biceps brachii Like most muscles, both the biceps and triceps do some primary actions as well as assist in some additional actions. The main action of the biceps is supination of the [forearm](https://3dmusclelab.com/elbow-joint-and-forearm/). That’s the action that happens when we rotate to [turn our forearm](https://3dmusclelab.com/elbow-and-forearm-in-movement/) and hand palm up. Both heads of the muscle work together to do that action. The two heads also work together to assist in [flexing](https://3dmusclelab.com/anatomical-terms-for-movements/) the forearm at the elbow and flexing the arm at the shoulder. The biceps is not the prime mover in either of these actions, but it assists other muscles to help create them. Because of the position of its proximal attachment on the scapula, the long head can also help stabilize the shoulder joint. ### Triceps brachii All three heads of triceps brachii work together to create its main action, which is extension of the forearm at the [elbow](https://3dmusclelab.com/golfers-elbow-and-tennis-elbow/). The long head, because of its proximal attachment to the scapula, can assist other muscles in extension and adduction of the arm at the shoulder joint. Like the long head of the biceps, it can also contribute to stabilizing the [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/) at the shoulder joint. The lateral head helps stabilize the elbow joint in extension when we want to add a supination or pronation movement, or do fine motor movements with our [hands and fingers](https://3dmusclelab.com/hand-and-wrist-anatomy/). ## Biceps and triceps relationship As we describe the individual movements and stabilization actions of the biceps and triceps, you can see that they are related. The biceps flexes the forearm at the elbow, and the triceps extends the forearm at the elbow. When one is [concentrically contracting](https://3dmusclelab.com/muscle-contractions/), the other is lengthening and relaxing to allow movement to happen. They also work together, along with many other muscles, to contribute to stabilization at the shoulder. The tendinous ends of the long heads of both biceps and triceps are part of the collective group of muscles that stabilize the ball of the humerus in the socket of the scapula. ## Conclusions The biceps brachii and triceps brachii are two important muscles for positioning our forearms. Those are key actions for all daily movements we do that involve grasping with our hands. We need our biceps and triceps to initiate movements from grabbing the steering wheel to typing. To better understand how these muscles contribute to those functional movements, it’s helpful to think about how they act in relation to each other. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 13: Shoulder, Arm, and Hand. In Clinical Application of Neuromuscular Techniques. Volume 1 (Second Edition). New York, NY: Churchill Livingstone Publishing. [Soubhagya, R.N., K. Ashwin, S.J. Kumar Madhan, et al. 2008. Four-headed biceps and triceps brachii muscles, with neurovascular variation. Anatomical Science International 83:107–111.](https://pubmed.ncbi.nlm.nih.gov/18507620/) [Tiwana, M.S., M.A. Sinkler, B. Bordoni. 2023. Anatomy, Shoulder and Upper Limb, Triceps Muscle. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536996/](https://www.ncbi.nlm.nih.gov/books/NBK536996/) [Tiwana, M.S., M. Charlick, M.A. Varacallo. 2024. Anatomy, Shoulder and Upper Limb, Biceps Muscle. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519538/](https://www.ncbi.nlm.nih.gov/books/NBK519538/) --- Source: https://3dmusclelab.com/the-deep-neck-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Neck # The Deep Neck Muscles The deep neck muscles are an important group for understanding both neck function and dysfunction. Our deep neck muscles do more of our postural maintenance, but they also assist other muscles with movement. ![The Deep Neck Muscles](https://3dmusclelab.com/wp-content/uploads/2024/04/posterior-neck-h.jpg) Just like we have interwoven layers of superficial and deeper [myofascia](https://3dmusclelab.com/what-is-muscle-fascia/) that make up the soft tissue of our torso, pelvis, legs, and arms, we also have more superficial layers and deep layers of muscles in the neck. In this article, we’ll continue our exploration of the [neck muscles](https://3dmusclelab.com/neck-muscles-superficial/) by looking at the deeper layers of neck muscles. We’ll learn which muscles comprise those deep layers, where they’re located, and what their main actions are. We’ll also go over some of the especially important functions of these [muscles](https://3dmusclelab.com/what-is-a-muscle/). There are different ways that we can categorize this group of deep neck muscles. To help you connect the muscles to their shared functions, in the list below we’ll group these muscles by some of their [main actions](https://3dmusclelab.com/muscle-origin-insertion-and-action/). It’s important to keep in mind, however, that all of these muscles have more than one action. And, as with the more superficial neck muscles we discussed in our last article, most of these deep neck muscles are found in pairs. Therefore, they have both bilateral and unilateral actions as well. Let’s take a look at the deep neck muscles I cover in this article. ## Quick facts Origin · Insertion · Action - **Origin**: **Spinalis cervicis:** lower section of the ligamentum nuchae and C6 or C7 to T1 or T2 **Iliocostalis cervicis:** angle of the ribs 3–6 **Longissimus cervicis:** transverse processes of T1-T5 **Longissimus capitis:** transverse processes of T1-T5 and the articular processes of C5-C7 **Semispinalis cervicis:** transverse processes of T1 to T5 or T6 **Semispinalis capitis:** articular processes of C3 or C4 to C7 and the transverse processes of T1 to T6 or T7 **Multifidus (cervical):** articular processes of C4-C7 **Rotatores (cervical):** transverse processes of the cervical vertebrae **Longus colli:** transverse processes or bodies of the vertebrae between C1 and T3 **Longus capitis:** transverse processes of C3 to C6 **Rectus capitis lateralis:** transverse processes of C1 **Rectus capitis anterior:** transverse process of C1 **Rectus capitis posterior major:** spinous process of C2 **Rectus capitis posterior minor:** C1 **Obliquus capitis superior:** transverse process of C1 **Obliquus capitis inferior:** spinous process of C2 - **Insertion**: **Spinalis cervicis:** spinous processes of C2-C4 **Iliocostalis cervicis:** transverse processes of C4-C6 **Longissimus cervicis:** transverse processes of C2-C6 **Longissimus capitis:** mastoid process **Semispinalis cervicis:** spinous processes of C2 to C5 **Semispinalis capitis:** occipital bone **Multifidus (cervical):** spinous processes of C2 to C7 **Rotatores (cervical):** spinous processes of the cervical vertebrae **Longus capitis:** base of the occipital bone **Rectus capitis lateralis:** jugular process on the occipital bone **Rectus capitis anterior:** base of the occipital bone **Rectus capitis posterior major:** occipital bone **Rectus capitis posterior minor:** occipital bone **Obliquus capitis superior:** occipital bone **Obliquus capitis inferior:** transverse processes of C1 - **Action**: Cervical erector spinae (spinalis, longissimus, iliocostalis): extend the neck (bilateral), lateral flexion of the neck (unilateral) **Semispinalis cervicis and capitis:** extend the head and neck (bilateral), same-side lateral flexion and opposite-side rotation (unilateral) **Multifidus (cervical):** extension of the neck (bilateral), same-side lateral flexion and opposite-side rotation (unilateral) **Rotatores (cervical):** extension of the neck (bilateral), rotate the neck to the opposite side (unilateral) **Longus colli:** flex the neck (bilateral), same-side lateral flexion and opposite-side rotation (unilateral) **Longus capitis:** flex the neck (bilateral), rotates the neck to the same side (unilateral) **Rectus capitis anterior:** stabilization at the atlantooccipital joint, assists flexion of the neck (bilateral) **Rectus capitis lateralis:** stabilization at the atlantooccipital joint, same-side lateral flexion of the head on the neck (unilateral) **Suboccipitals:** stabilizing the head on the neck, hyperextension of the head on the neck **Obliquus capitis superior:** also lateral flexion of the head to the same side **Obliquus capitis inferior:** also rotation of the head to the same side ## Deep muscles of the neck ### Erector spinae – cervical portions Each of the [erector spinae muscles](https://3dmusclelab.com/erector-spinae-muscles/) which we have covered already in a different article, have portions that are specific to the cervical [spine](https://3dmusclelab.com/exploring-the-spine/). This group of cervical muscles is the most superficial of the muscles we’ll look at in this article. They include: - Spinalis cervicis - Iliocostalis cervicis - Longissimus cervicis - Longissimus capitis ### Deep neck extensors - Semispinalis cervicis - Semispinalis capitis - Multifidus (cervical segments) - Rotatores (cervical segments) ### Deep neck flexors - Longus colli - Longus capitis - Rectus capitis lateralis - Rectus capitis anterior ### Head extension and postural holding of the head – Suboccipitals - Rectus capitis posterior major - Rectus capitis posterior minor - Obliquus capitis superior - Obliquus capitis inferior ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Deep neck muscle locations Remember that muscle attachments vary from person to person. It’s important to keep this in mind as I describe ranges of attachments for the deep neck muscles in this article. If you read other anatomy references, you’ll notice that the attachment points for the deep neck muscles are listed slightly differently in different sources. The variability from person to person is the reason for these differences. In this section of the article, I’ll describe the broad location of the deep neck muscles. For more specific descriptions of the muscle attachments, scroll down and you’ll find those listed at the end of this article. ### Cervical portions of the erector spinae muscles Spinalis cervicis (sometimes called spinalis colli) attaches to the cervical vertebrae, the lower section of the ligamentum nuchae, and the upper thoracic vertebrae. Iliocostalis cervicis (sometimes called iliocostalis colli) attaches to the mid to lower cervical vertebrae and to the angle of the ribs 3 – 6. Longissimus cervicis (sometimes called longissimus colli) attaches to most of the cervical vertebrae and to the upper thoracic vertebrae. Finally, longissimus capitis attaches at one end to the mastoid process, that bony bump behind your ear. At its other end, it attaches to the upper thoracic vertebrae and lower cervical vertebrae. ### Deep neck muscles: extensors (the transversospinalis group) The transversospinalis group is the name for the group of deep spinal muscles that lay underneath the erector spinae group. They include the semispinalis cervicis, semispinalis capitis, and a cervical section of the multifidus and the rotatores. Let’s take a look at where these deep neck muscles are located. #### Semispinalis cervicis and semispinalis capitis Individual sections of semispinalis cervicis span five or six vertebrae and attach to most of the cervical vertebrae and the upper thoracic vertebrae. The semispinalis capitis attaches at its proximal end to the occipital bone of our skull and then attaches to most of the cervical vertebrae and the upper thoracic vertebrae. #### Multifidus and rotatores (the cervical portions) The individual sections of the cervical multifidus span two to four vertebrae. They attach to most of the cervical vertebrae. The cervical portions of the rotatores are a little smaller. They span one or two vertebrae and attach along the cervical spine. Some anatomists further divide the rotatores group and consider the sections that span one vertebra as rotatores brevis and the sections that span two vertebrae as rotatores longus. ![The Deep Neck Muscles](https://3dmusclelab.com/wp-content/uploads/2024/04/posterior-neck.jpg) ### Deep neck flexors On the front of our neck, we have a group of deep neck muscles that often don’t get a lot of attention. Those muscles are collectively referred to as the deep neck flexors. They include longus colli, longus capitis, rectus capitis lateralis, and rectus capitis anterior. The first of these deep neck muscles on the front of the neck, longus colli, varies in its attachment points from person to person. It’s often described as having three sections, a superior, an inferior section, and an intermediate or vertical section. The sections of this muscle attach at various points to the cervical and first couple of thoracic vertebrae. Longus capitis attaches at its proximal end to the base of the occipital bone and at its distal end to the cervical vertebrae. The other two deep neck muscles in this flexor group are rectus capitis lateralis and rectus capitis anterior. Rectus capitis lateralis attaches at its superior end to the occipital bone. At its inferior end, it attaches to C1. Rectus capitis anterior attaches to the base of the occipital bone at its superior end. At its inferior end, it also attaches to C1. ### Head extensors/suboccipitals The suboccipital muscles are all deep neck muscles that are found, as the name of this group suggests along the base of the skull, the occiput. Most of this group of deep neck muscles attaches to the occipital bone and either C1 or C2. Scroll to the appendix of this article for more specific attachment details. ## Actions of the deep neck muscles in movement and posture ### Cervical portions of the erector spinae muscles As I covered in my previous article, [Exploring The Erector Spinae Muscles](https://3dmusclelab.com/erector-spinae-muscles/), each of the erector spinae muscles along the back has a section specific to the cervical spine. The cervical parts of spinalis, longissimus, and iliocostalis all work together. When they act bilaterally, they extend the neck. When they [contract](https://3dmusclelab.com/muscle-contractions/) unilaterally, they can do lateral flexion of the neck. ### Deep neck extensors The deep neck extensor muscles, and deep neck flexors muscles, work together to balance the forward/back action and position of the neck. We could consider them the “core” of our neck in the forward/backward direction. Specifically, the semispinalis cervicis and semispinalis capitis extend the head and neck when they’re working bilaterally. When either of those muscles acts unilaterally, they can do lateral flexion of the head and neck to the same side (ipsilateral). They can also rotate the head and neck to the opposite side (contralateral) when acting unilaterally. Deep to the cervical portions of the erector spinae muscles, we have the multifidus muscles of the neck. Deep to the multifidus muscles, we find the rotatores of the neck. When these muscles act bilaterally, both the multifidus and rotatores work along with the cervical parts of the erector spinae and contribute to extension of the neck. Unilaterally, the multifidus muscle does lateral flexion of the neck to the same side and rotation of the neck to the opposite side. Unilaterally, the rotatores act to rotate the neck to the opposite side. ### Deep neck flexors To balance the actions of the many deep muscles on the back of our neck that extend the neck, we have a group of deep muscles on the front of the neck that flex the neck. Longus colli and longus capitis act to flex the neck when they work bilaterally. Unilaterally, longus colli does lateral flexion of the neck to the same side and rotation of the neck to the opposite side. Longus capitis rotates of the neck to the same side when acting unilaterally. Rectus capitis lateralis and rectus capitis anterior primarily have a stabilization function, specifically at the atlantooccipital joint (where the head meets C1). However, rectus capitis anterior also assists in flexion of the neck when acting bilaterally. When working unilaterally, rectus capitis lateralis can also assist with lateral flexion of the head on the neck to the same side, specifically at the atlantooccipital joint. ### Head extensors/suboccipitals One of the important functions of this group of deep neck muscles is [stabilizing the position of the head](https://3dmusclelab.com/posture-and-smartphone/) on the neck, rather than as prime movers. Additionally, with the actions of these muscles, it’s important to keep in mind that we’re talking about movement of the head here, not movements of the neck. These are small, deep muscles and there is some inconsistency among anatomy references about which movements each of these suboccipital muscles assist with. What is consistent is that they contribute to hyperextension of the head on the neck. Remember that hyperextension here just means extension past the point of neutral in [anatomical position](https://3dmusclelab.com/anatomical-position/). It’s a normal movement. Because of its location and fiber direction, obliquus capitis superior also does lateral flexion of the head to the same side. For similar reasons of location and fiber direction, obliquus capitis inferior also does rotation of the head to the same side. The other three suboccipital muscles may also contribute to rotation of the head to the same side, however, anatomy references don’t all agree on this movement. ## Conclusion The deep neck muscles are an important group for understanding both neck function and dysfunction. Our deep neck muscles do more of our postural maintenance, but they also assist other muscles with movement. Knowing the attachments and main actions of the deep neck muscles can help us understand when they are working well and when something is out of balance. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Jung B., A.C. Black, B.S. Bhutta. 2024. Anatomy, Head and Neck, Neck Movements. [Updated 2023 Nov 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557555/](https://www.ncbi.nlm.nih.gov/books/NBK557555/) [Myers, T. Chapter 12: The Neck and Cranium (Part 1): Touring the Motor Cylinder. In: Body3 A Therpist’s Anatomy Reader.](https://www.anatomytrains.com/product/body3-color-illustrations/) [Roijezon, U., G. Jull, M. Djupsjobacka, S.E. Salomoni, P.W. Hodges. 2021. Deep and superficial cervical muscles respond differently to unstable motor skill tasks. Human Movement Science. 80:102893. 9pgs.](https://www.sciencedirect.com/science/article/pii/S016794572100141X) ## Appendix: Specific attachments of the deep neck muscles ### Cervical portions of the erector spinae muscles Spinalis cervicis (sometimes called spinalis colli) attaches at the proximal end to the spinous processes of C2-C4 and at the distal end to the lower section of the ligamentum nuchae and C6 or C7 to T1 or T2. Some anatomists also describe a spinalis capitis muscle that has the same distal attachments as spinalis cervicis, but proximally it becomes part of semispinalis capitis. Iliocostalis cervicis (sometimes called iliocostalis colli) attaches at the proximal end on the transverse processes of C4-C6 and at the distal end on the angle of the ribs 3 – 6. Longissimus cervicis (sometimes called longissimus colli) attaches at its proximal end on the transverse processes of C2-C6 and at its distal end on the transverse processes of T1-T5. Longissimus capitis attaches at its proximal end on the mastoid process, that bony bump behind your ear. At its distal end, it attaches to the transverse processes of T1-T5 and the articular processes of C5-C7. ### Deep neck extensors (the transversospinalis group) #### Semispinalis cervicis At its proximal end, the individual sections of semispinalis cervicis attach to the spinous processes of C2 to C5. Each section then spans five or six vertebrae to attach at the distal end to the transverse processes of T1 to T5 or T6. #### Semispinalis capitis The semispinalis capitis attaches at its proximal end to the occipital bone of our skull. It then attaches at its distal end to the articular processes of C3 or C4 to C7 and the transverse processes of T1 to T6 or T7. #### Multifidus (the cervical portions) The attachments of the individual sections that make up the cervical multifidus attach at their proximal end to the spinous processes of C2 to C7. Each small muscular section of the multifidus then spans from two to four vertebrae to attach at the distal end to the articular processes of C4-C7. #### Rotatores (the cervical portions) At their proximal end, the rotatores attach to the spinous processes of the cervical vertebrae. They then span one or two vertebrae to attach at their distal end to the transverse processes of the cervical vertebrae. ### Deep neck flexors The first of these, longus colli, varies in its attachment points from person to person and is often further described as having three sections, a superior, an inferior section, and an intermediate or vertical section. For our purposes here, understand that the sections of this muscle attach at various points to the transverse processes or bodies of the vertebrae between C1 and T3. The second of these deep flexor muscles, longus capitis, is a little easier to describe specific attachments for. Longus capitis attaches at its proximal end to the base of the occipital bone. At the distal end, longus capitis attaches to the transverse processes of C3 to C6. The other two muscles in this deep flexor group are rectus capitis lateralis and rectus capitis anterior. Rectus capitis lateralis attaches at its superior end to the jugular process (a bony protrusion) on the occipital bone. At its inferior end, it attaches to the transverse processes of C1. Rectus capitis anterior attaches to the base occipital bone at its superior end. At its inferior end, it also attaches to the transverse process of C1. ### Head extensors/suboccipitals Rectus capitis posterior major attaches at its superior end to the occipital bone. At its inferior end, it attaches to the spinous process of C2. Rectus capitis posterior minor also attaches at its superior end to the occipital bone. At its inferior end, it attaches to C1. At its superior end, obliquus capitis superior attaches to the occipital bone. At its inferior end, it attaches to the transverse process of C1. The obliquus capitis inferior attaches at its superior end to the transverse processes of C1 and at its inferior end to the spinous process of C2. --- Source: https://3dmusclelab.com/deep-six-lateral-rotator-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # What And Where Are The Deep Six Lateral Rotator Muscles? The deep six lateral rotator muscles are often discussed as a group because they have the same primary action and they generally function together. They include: piriformis, obturator internus, obturator externus, gemellus inferior, gemellus superior, and the quadratus femoris. All six of the muscles in this group originate somewhere on the pelvis and run laterally across the pelvis to attach to the greater trochanter. ![Deep Six Lateral Rotators](https://3dmusclelab.com/wp-content/uploads/2019/07/deep-six-no-bg-fi.jpg) The deep six lateral rotator muscles are often discussed as a group because they have the same primary action and they generally function together. We’ve already covered one of the deep six lateral rotator muscles, the [piriformis muscle](https://3dmusclelab.com/piriformis-muscle/) in a separate post. The piriformis muscle sometimes gets singled out of the group because it can be the culprit behind [piriformis syndrome](https://3dmusclelab.com/piriformis-syndrome/) and can be associated with sciatica-like pain. But, what exactly is the deep six lateral rotator muscle group? ## Quick facts Origin · Insertion · Action - **Origin**: **Piriformis:** anterior sacrum **Gemellus superior:** ischial spine **Gemellus inferior:** ischial spine **Obturator internus:** internal surface of the obturator foramen **Obturator externus:** external surface of the obturator foramen **Quadratus femoris:** ischial tuberosity - **Insertion**: **Piriformis:** greater trochanter of the femur **Gemellus superior:** greater trochanter of the femur **Gemellus inferior:** greater trochanter of the femur **Obturator internus:** greater trochanter of the femur **Obturator externus:** greater trochanter of the femur **Quadratus femoris:** greater trochanter of the femur - **Action**: **Piriformis:** laterally rotates the femur at the hip joint; may assist abduction of the thigh when the hip is flexed; may contribute to extension of the hip **Gemellus superior:** laterally rotates the femur at the hip joint; possibly assists abduction of the thigh if the hip joint is flexed **Gemellus inferior:** laterally rotates the femur at the hip joint; can assist abduction of the thigh if the hip joint is flexed **Obturator internus:** laterally rotates the femur at the hip joint; can assist abduction of the thigh if the hip joint is flexed **Obturator externus:** laterally rotates the femur at the hip joint; may assist adduction of the thigh, depending on leg position **Quadratus femoris:** laterally rotates the femur at the hip joint; may assist adduction of the thigh, depending on leg position ## Which muscles are included in the deep six lateral rotator muscle group? There are six muscles in this group as the name suggests. They include: [piriformis](https://3dmusclelab.com/piriformis-muscle/), obturator internus, obturator externus, gemellus inferior, gemellus superior, and the quadratus femoris. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Where are the deep six lateral rotator muscles located? All six of the muscles in this group originate somewhere on the pelvis and run laterally across the pelvis to attach to the greater trochanter. Let’s get more specific about the attachments for each of these muscles. #### Origins - The piriformis muscle originates on the anterior sacrum. - The gemellus inferior and gemellus superior originate on the ischial spine. - The obturator externus originates on the external surface of the obturator foramen. - The obturator internus originates on the internal surface of the obturator foramen. - The quadratus femoris originates on the ischial tuberosity. #### Insertion All six of the deep six lateral rotators insert on the greater trochanter of the femur. ## What actions do the deep six lateral rotator muscles do? Generally, recent research suggests the overall function of this group of muscles is for support and stability of the hip joint, rather than big movements. The overall job of the deep six lateral rotators is to keep the “ball” of the ball and socket joint (the head of the femur) in the “socket” (the acetabulum of the pelvis) when we are walking, running or doing other movements (Yoo et al., 2015). Specifically, all six of these muscles laterally rotate the femur at the hip joint. Researchers are still exploring whether some of these muscles also assist with other movements. As all of the deep six lateral rotators are located deep to at least one other muscle, it makes it more difficult to insert the electrodes for electromyography (EMG), which are typically used in the laboratory to determine muscle action. Some researchers suggest that obturator internus gemellus inferior, and possibly gemellus superior, can assist with abduction of the thigh if the hip joint is flexed (Chaitow and DeLany, 2011; Yoo et al., 2015). Piriformis may also assist in abduction of the thigh when the hip is flexed and recent EMG analysis also suggests that it may contribute to extension of the hip (Yoo et al., 2015). Some researchers are now finding that quadratus femoris and obturator externus may assist with adduction of the thigh, depending on what position the leg is in (Yoo et al., 2015). If you want to learn more about the deep six lateral rotator muscles, check out our related articles. If you want to learn more about the piriformis muscle specifically, check out the related articles in our series on the piriformis: The [Piriformis Muscle](https://3dmusclelab.com/piriformis-muscle/) and What Is [Piriformis Syndrome](https://3dmusclelab.com/piriformis-syndrome/). The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Chaitow, L. and J. DeLany. 2011. The Hip. *In* Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition). Yoo, S., I. Dedova, N. Pather. 2015. An appraisal of the short lateral rotators of the hip. Clinical Anatomy. 28:800-812. --- Source: https://3dmusclelab.com/deltoid-muscles/ Author: David Keil · Updated: 2026-05-21 Muscle reference · Shoulder # The Deltoid Muscles The deltoid is a superficial shoulder muscle. The deltoid muscles are triangular-shaped muscles found on the upper arm and shoulder. They each have three distinct sets of fibers, often called the anterior, middle, and posterior deltoids. ![Deltoid Muscle](https://3dmusclelab.com/wp-content/uploads/2026/04/deltoid-muscle.jpg) The deltoid is a superficial shoulder muscle that we’re probably all somewhat familiar with. But like other structures in the body, the deltoid muscles have some interesting complexities that you might not be aware of. In this article, we’ll review the location and actions of the deltoid muscles. We’ll also look a little closer at how the deltoids work, alone and with other muscles, to create and resist particular actions. ## Quick facts Origin · Insertion · Action - **Origin**: **Anterior (clavicular) fibers:** lateral (outer) third of the clavicle **Middle (acromial) fibers:** acromion of the scapula **Posterior (scapular) fibers:** lateral portion of the spine of the scapula - **Insertion**: **All three sets of fibers:** deltoid tuberosity, a bony prominence on the lateral humerus - **Action**: **All three sets:** abduction of the arm at the shoulder (together between 60 and 90 degrees) **Anterior fibers:** assist flexion and internal rotation of the arm at the shoulder; adduction when the arm is abducted less than 60 degrees **Posterior fibers:** assist extension and external rotation; adduction when the arm is abducted less than 60 degrees ## Location The deltoid muscles are triangular-shaped muscles found on the upper arm and [shoulder](https://3dmusclelab.com/shoulder-girdle/). Their name is a reference to their shape, as delta refers to the triangular Greek letter. One of the interesting things about the deltoids is that they each have three distinct sets of fibers. Those sets of fibers are often called the anterior, middle, and posterior deltoids, or sometimes the [clavicular](https://3dmusclelab.com/sternoclavicular-and-acromioclavicular-joint/), acromial, and scapular deltoids, based on where they attach. ### Deltoid muscle attachments For small muscles, the deltoid muscles have many attachments. As I said earlier, each set of fibers has specific attachments. The anterior, or clavicular, fibers of the deltoid attach to the clavicle, as their name suggests. Specifically, that portion of the deltoid originates on the lateral (outer) third of the clavicle (collarbone). The middle, or acromial, fibers originate on the acromion of the scapula (shoulder blade). Remember that the acromion is the bony shelf of the [scapula](https://3dmusclelab.com/scapula/) that juts out over the place where the humeral head fits into the glenoid fossa to create the shoulder joint itself. Finally, the posterior, or scapular, fibers originate on the lateral portion of the spine of the scapula. Remember that the spine of the scapula is the bony ridge that runs horizontally across the scapula. All three sets of deltoid muscle fibers then come together to insert onto the deltoid tuberosity, a bony prominence on the lateral humerus. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Deltoid muscle actions ### Abduction Because the deltoid muscle fibers attach in different places and run at slightly different angles, we could consider the deltoids as really three different muscles when it comes to [actions](https://3dmusclelab.com/muscle-origin-insertion-and-action/). The action that the deltoid muscles are most known for is abduction of the arm at the shoulder. But even this action is more complex than we might typically think it is. The three sections of this muscle work together to abduct the arm at the shoulder only when the arm is abducted between 60 and 90 degrees. The first part of abduction of the arm (about 15 degrees) is actually an action of the little [supraspinatus muscle](https://3dmusclelab.com/rotator-cuff-muscles/), one of the [rotator cuff muscles](https://3dmusclelab.com/rotator-cuff-muscles-and-movement/). Then the middle deltoid fibers start working, and finally, the remaining deltoid fibers pitch in and help out with this action. ### Other actions In addition to abduction of the arm, the anterior and posterior sections of fibers have other movements that they contribute to. The anterior fibers assist with flexion and internal rotation of the [arm at the shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/). The posterior fibers assist with extension and external rotation. Because of the fiber direction and direction of pull, when the arm is abducted less than 60 degrees, the anterior and posterior fibers can also contribute to adduction. This means that the deltoid muscle can be, in a sense, an antagonist to itself! ### Stabilization Along with their role in dynamic actions, the deltoid muscles are also important for [stabilization](https://3dmusclelab.com/muscle-contractions/). Particularly when we’re holding something heavy, the deltoids work with the [rotator cuff](https://3dmusclelab.com/rotator-cuff-muscles-shoulder-pain/) and other muscles to prevent the humeral head from dislocating. They all work together to keep the head of the humerus in the socket as we move our arm in different directions. ## Conclusion The deltoid muscles are superficial muscles of the shoulder. They have three distinct sets of fibers. This complex organization makes them versatile muscles that can help with multiple actions, stabilization, and even work as antagonists to themselves. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Elzanie, A., and M.A. Varacallo. 2026. Anatomy, Shoulder and Upper Limb, Deltoid Muscle. [Updated 2024 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.](https://www.ncbi.nlm.nih.gov/books/NBK537056/) Gilroy, A.M., B.R. MacPherson, and J.C. Wikenheiser (Eds.) 2025. Atlas of Anatomy. (5th ed.) Thieme. --- Source: https://3dmusclelab.com/jaw-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Jaw # The Jaw Muscles There are many small muscles that are important for complex functions like chewing, swallowing, and speaking. As a group, all of the jaw muscles are involved in the series of actions we call chewing, technically called mastication. ![Jaw Muscles](https://3dmusclelab.com/wp-content/uploads/2024/05/jaw-muscles.jpg) In my last two articles, we’ve gone into the layers of [muscles](https://3dmusclelab.com/what-is-a-muscle/) that [stabilize](https://3dmusclelab.com/the-deep-neck-muscles/) and [move the head and neck](https://3dmusclelab.com/neck-muscles-superficial/). In this article, we’ll continue up that chain and go into the jaw muscles. There are many small muscles that are important for complex functions like chewing, swallowing, and speaking. However, don’t get overwhelmed by the list of names. My intention here is to give a general overview of these muscles, their locations, and actions so that you can dive deeper when it’s relevant to you. ## Quick facts Origin · Insertion · Action - **Origin**: **Masseter:** maxillary process and the zygomatic arch of the zygomatic bone **Temporalis:** temporal fossa of the skull **Medial pterygoid:** pterygoid plate of the sphenoid bone, the palatine bone, and the maxilla **Lateral pterygoid:** greater wing and lateral pterygoid plate of the sphenoid bone **Suprahyoid group:** mandible **Sternothyroid:** manubrium of the sternum - **Insertion**: **Masseter:** ramus and the coronoid process of the mandible **Temporalis:** coronoid process of the mandible **Medial pterygoid:** ramus and angle of the mandible **Lateral pterygoid:** condyle of the mandible, and sometimes part of the articular disc and capsule of the temporomandibular joint **Suprahyoid group:** superior part of the hyoid bone **Infrahyoid group (except sternothyroid):** lower aspect of the hyoid bone **Sternothyroid:** thyroid cartilage - **Action**: **Masseter:** elevation of the mandible (closes the mouth), protrusion and retraction of the mandible **Temporalis:** elevation of the mandible (closing the mouth), retracting the mandible **Lateral pterygoid:** depress and protrude the mandible (bilateral), side-to-side movement of the mandible (unilateral) **Medial pterygoid:** elevate the mandible (close the jaw), protrude the jaw, side-to-side movement of the jaw **Suprahyoid group:** elevate and position the hyoid bone anteriorly or posteriorly; two muscles assist with depressing the mandible **Infrahyoid group:** depress the larynx (voice box) and hyoid bone ## Muscle names The jaw muscles that I’ll go over in this article include: - Masseter - Temporalis - Medial pterygoids - Lateral pterygoids - Suprahyoid muscle group - Digastric - Stylohyoid - Mylohyoid - Geniohyoid - Infrahyoid muscle group - Sternohyoid - Sternothyroid - Thyrohyoid - Omohyoid ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Attachments ### Bones to know There are several relevant [bones](https://3dmusclelab.com/bone-breaks-fractures-and-heals/) to know to understand where the jaw muscles attach. The mandible is the technical name for the bone that makes up the lower part of our jaw. The temporal bone is a large bone at the side of our skull. We have one on the right and one on the left side of our skull. Where these bones meet is called the temporomandibular joint. The temporomandibular joint is the [joint](https://3dmusclelab.com/synovial-joint/) that moves every time we open and close our mouth. We also have a pair (a right and left side) of zygomatic bones. These bones form the lower part of our eye socket and “cheekbones.” The hyoid bone is a small U-shaped bone that floats in a sea of [myofascial tissue](https://3dmusclelab.com/what-is-muscle-fascia/) about halfway down our neck and at the front. A number of muscles attach to it. ### Masseter and temporalis muscles The masseter is the most superficial of the jaw muscles, however, it has two sections, a superficial portion, and a deeper part. At its superior end, it attaches to the maxillary process (projection of bone) and the zygomatic arch of the zygomatic bone. At its inferior end, both sets of fibers converge to attach onto the ramus (branch of bone) and the coronoid process (projection of bone) of the mandible. The temporalis attaches at its superior end to the temporal fossa of our skull. All the fibers then come together to attach at the inferior end to the coronoid process of the mandible. ### Medial pterygoids and lateral pterygoids The medial and lateral pterygoids are some of our jaw muscles that are found a little deeper. The medial pterygoid has two heads, a deep head and a superficial head. At one end the sets of fibers of the medial pterygoid attach to several bones in our face: the pterygoid plate of the sphenoid bone, the palatine bone, and the maxilla. The fibers then come together to attach to the ramus and angle of the mandible. The lateral pterygoid muscle also has two heads, a superior and inferior portion. At one end the multiple sets of fibers of the lateral pterygoid attach to the greater wing and lateral pterygoid plate of the sphenoid bone. The fibers come together to attach to the condyle of the mandible, and sometimes also part of the the articular disc and capsule of the temporal-mandibular joint. ### Suprahyoid muscle group The word supra means above. Hyoid, of course, refers to the small, but very important bone midway down the front of our neck that I described earlier. So based on breaking down the name, you could guess that the suprahyoid muscles are a group of jaw muscles that attach to the superior, or top part, of the hyoid bone. These four muscles connect the mandible, the lower part of our jaw, to the superior part of the hyoid bone. ### Infrahyoid muscle group Infra means below. So you can probably guess that the infrahyoid muscles are a group of jaw muscles that attach to the inferior, or lower part, of the hyoid bone. Like the suprahyoid muscles, the infrahyoid muscles are all muscles that as a group are found on the anterior, or front side, of the cervical spine. While each of the four jaw muscles in this group has a [specific attachment](https://3dmusclelab.com/muscle-origin-insertion-and-action/) at each end, it’s enough for our purposes here to understand that the infrahyoid muscles are found on the lower part of the front of the cervical spine. With the exception of the sternothyroid, they all attach to the lower aspect of the hyoid bone in various places. The sternothyroid muscle in this group attaches to the thyroid cartilage at its superior end and the manubrium of the sternum at its inferior end. ## Actions ### Masseter and temporalis muscles As a group, all of the jaw muscles below are involved in the series of actions we call chewing, technically called mastication. That includes the opening, closing, and side-to-side actions of our jaw. Specifically, the masseter muscle does elevation of the mandible (closes the mouth) and does protrusion and retraction of the mandible which aids chewing. The temporalis is engaged in elevation of the mandible (closing the mouth) and retracting the mandible (pulling the lower jaw in). ### Lateral pterygoids and medial pterygoids The two heads of each lateral pterygoid can function bilaterally or unilaterally. When the two heads are acting bilaterally, they work to depress and protrude the mandible. Unilaterally, they can create a side-to-side movement of the mandible (lower jaw). The medial pterygoid acts to elevate the mandible (close the jaw) and protrude the jaw. Additionally, it works with the lateral pterygoid to create side-to-side movement of the jaw. ### Suprahyoid muscle group While there are additional actions specific to each of the individual muscles, generally, the suprahyoid muscle group acts primarily to elevate and position the hyoid bone either anteriorly or posteriorly, as needed. Two muscles in this group also assist with depressing the mandible. These actions together help support the complex actions of swallowing and speaking. ### Infrahyoid muscle group As with the suprahyoid group, there are additional [actions](https://3dmusclelab.com/muscle-contractions/) specific to each of the individual infrahyoid muscles. However, generally, the infrahyoid muscle group acts primarily to depress the larynx (voice box) and hyoid bone. Those actions happen when we are swallowing and speaking. Because this muscle group is located on the inferior side of the hyoid bone, this muscle group is also important in balancing the tension with the suprahyoid muscle group on the superior side of the hyoid bone. The balance of tension between these two groups helps support maintaining the important hyoid bone in the right position. ## Why learn the jaw muscles? While the details about the jaw muscles and their locations may not necessarily be relevant to you, their functions certainly are. These are the muscles involved in chewing, swallowing, and speaking. These are definitely activities that we all engage in. And if there is dysfunction in these muscles and their actions, then we can experience some very serious issues in essential daily functions. For example, teeth grinding, jaw pain, some types of headaches, and one common dysfunction that I will cover in a separate article, temporomandibular joint disorder (TMJ disorder) can all result if there is dysfunction in this group of muscles. (Temporomandibular joint disorder is not one single issue, but actually the name for a collection of symptoms that occur when there is pain and dysfunction at this joint.) You can imagine the challenges that any of those problems would present to daily function. Hopefully, you can see why understanding the healthy function of the jaw muscles can help us better understand what happens when there is dysfunction. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Basit H., M.A.Tariq, M.A. Siccardi. 2024. Anatomy, Head and Neck, Mastication Muscles. [Updated 2023 Jun 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541027/](https://www.ncbi.nlm.nih.gov/books/NBK541027/) Chaitow, L. and J. DeLany. 2011. Chapter 12: The Cranium. In Clinical Application of Neuromuscular Techniques. Volume 1 (Second Edition). New York, NY: Churchill Livingstone Publishing. [Jung, B., A.C. Black, B.S. Bhutta. 2024. Anatomy, Head and Neck, Neck Movements. [Updated 2023 Nov 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557555/](https://www.ncbi.nlm.nih.gov/books/NBK557555/) --- Source: https://3dmusclelab.com/latissimus-dorsi-and-teres-major/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Back # What And Where Are The Latissimus Dorsi And Teres Major Muscles? The latissimus dorsi is a large, powerful muscle on the back of the torso. Teres major often gets discussed along with the latissimus muscle because it’s a small muscle whose main job is to assist latissimus in some of its actions. ![Latissimus Dorsi Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/latissimus-mus.jpeg) The latissimus dorsi is a large, powerful muscle on the back of the torso. Teres major often gets discussed along with the latissimus muscle because it’s a small muscle whose main job is to assist latissimus in some of its actions. Due to its size and power, latissimus has the potential to affect a wide range of actions in the body. ## Quick facts Origin · Insertion · Action - **Origin**: **Latissimus dorsi:** spinous processes of T7-T12; via the thoracolumbar aponeurosis, all lumbar vertebrae, the sacrum, and the posterior third of the iliac crest **Teres major:** inferior angle of the scapula - **Insertion**: **Latissimus dorsi:** bicipital groove of the humerus **Teres major:** bicipital groove of the humerus - **Action**: **Latissimus dorsi:** medial rotation of the humerus when the arm is abducted, extension of the humerus, adduction of the humerus **Teres major:** medial rotation of the humerus when the arm is abducted, extension of the humerus, adduction of the humerus ## Where are the latissimus dorsi and teres major muscles located? Generally, the latissimus dorsi covers much of the back and teres major is found just superior to the latissimus where it connects from the torso to the humerus. ![Teres Major Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/teres-major-mus.jpeg) ### What is the origin of latissimus dorsi and teres major? Specifically, latissimus dorsi has a broad area of attachment that could be considered the “origin”. It attaches to the spinous processes of vertebrae T7-T12 and then via the thoracolumbar aponeurosis, a tendinous sheath of connective tissue, it connects to all of the lumbar vertebrae, the sacrum, and the posterior third of the iliac crest. Latissimus dorsi can also have an attachment on ribs 9-12 and the inferior angle of the scapula, as it moves up the torso. Teres major originates on the inferior angle of the scapula. ### What is the insertion of latissimus dorsi and teres major? Together, latissimus dorsi and teres major go from the inferior angle of the scapula to insert on the bicipital groove of the humerus. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What actions do the latissimus dorsi and teres major muscles do? The primary actions of both latissimus dorsi and teres major are: - Medial rotation of the humerus when the arm is abducted - Extension of the humerus - Adduction of the humerus Latissimus dorsi, due to its large area of attachment, is also intimately related to maintaining balanced movement and stability of the whole [shoulder complex](https://3dmusclelab.com/shoulder-girdle/) (Hawkes et al., 2019). Similarly, healthy range of motion in latissimus is important for a balanced gait pattern during walking. Recent research suggests that there is a synergy between latissimus dorsi on one side of the body and the gluteus maximus on the opposite side of the body during each walking step we take. This synergy functions to stabilize the low back, particularly the sacroiliac joint, as we walk (Feeney et al., 2018). The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Chaitow, L. and J. DeLany. 2011. Shoulder Arm and Hand. *In* Clinical Application of Neuromuscular Techniques. Volume 1 – The Upper Body (Second Edition). [Feeney, D.F., R.A. Capobianco, J.R. Montgomery, J. Morreale, A.M. Grabowski, and R.M. Enoka. 2018. Individuals with sacroiliac joint dysfunction display asymmetrical gait and a depressed synergy between muscles providing sacroiliac joint force closure when walking. Journal of Electromyography and Kinesiology. 43:95-103.](https://www.ncbi.nlm.nih.gov/pubmed/30267967) [Hawkes, D.H., O.A. Khaiyat, A.J. Howard, G.J. Kemp, and S.P. Frostick. 2019. Patterns of muscle coordination during dynamic glenohumeral joint elevation: An EMG study. PLOS One. 14(2):1-16.](https://www.ncbi.nlm.nih.gov/pubmed/30735521) --- Source: https://3dmusclelab.com/pectoralis-major/ Author: David Keil · Updated: 2026-05-21 Muscle reference · Shoulder # The Pectoralis Major Muscle The pectoralis major muscle is a large, broad, superficial muscle on the front of our chest. This muscle is actually a pair. We have a right and left pec major. ![Pectoralis Major Muscle](https://3dmusclelab.com/wp-content/uploads/2026/05/pectoralis-major-muscle.jpg) The pectoralis major muscle is a large, broad, superficial muscle on the front of our chest. This muscle is actually a pair. We have a right and left pec major. Unlike some other [muscles](https://3dmusclelab.com/muscles-when-we-age/) we’ve covered recently, you’ve probably heard of this muscle and have a general sense of where it’s located. That’s because these are muscles we train for many sports and athletic activities. Like most structures in our body, though, the pectoralis major muscle is more complex than we might imagine at first glance. Read on for a closer look at the attachments and actions of the pec major muscle. ## Quick facts Origin · Insertion · Action - **Origin**: **Clavicular head:** medial half of the clavicle **Sternal head:** sternum and costal cartilages 1-6 **Third portion:** anterior part of the connective tissue that forms part of the abdominal wall - **Insertion**: **All sections:** edge of the bicipital groove on the upper part of the humerus (fibers twist before inserting) - **Action**: **All fibers:** adduction, horizontal adduction, medial (internal) rotation **Clavicular fibers:** assist flexion of the arm at the shoulder Inferior fibers (sternal, costal, abdominal): assist extension of the flexed arm at the shoulder joint **Humerus fixed:** assists inspiration ## Location Most generally, our pectoralis major muscles are located on the upper part of the front of our chest. They are part of the shoulder complex and thoracic wall. More specifically, we can think of each side of the pectoralis major (right and left sides) as having three distinct parts based on the attachments and fiber directions. ### Pectoralis major muscle attachments One section of pec major originates on the medial half of the [clavicle](https://3dmusclelab.com/sternoclavicular-and-acromioclavicular-joint/) (collar bone). This is called the clavicular head of the muscle. A second part of this muscle originates on the sternum and costal cartilages 1-6. Remember that the costal cartilages are the cartilagenous area of the medial [ribs](https://3dmusclelab.com/ribcage/). That portion is called the sternal head of the pec major muscle. A third portion of the pectoralis major originates on the anterior part of the [connective tissue](https://3dmusclelab.com/what-is-connective-tissue/) that forms part of the abdominal wall. From its broad area of what we consider the [origin](https://3dmusclelab.com/muscle-origin-insertion-and-action/), all the fibers come together. The myofascial bands of the pectoralis major are arranged like the overlapping blades of a fan. If our arm is at our side, all the sections of the muscle twist before inserting at the edge of the bicipital groove on the upper part of the humerus. This means that the fibers on the inferior section of the origin attach at the superior part of the insertion, and those fibers that originate at the superior part of the origin attach at the inferior part of the insertion. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Pectoralis major muscle actions Because of their multiple attachments, the pec major muscles can affect multiple joints and directions of movement. The specific movements that this muscle contributes to depend on the starting position of the arm, [shoulder](https://3dmusclelab.com/shoulder-girdle/), and torso. Actions of pectoralis major also change based on what parts of the body are fixed or held in some way, and which are available to move. As with many [muscles](https://3dmusclelab.com/what-is-a-muscle/), ideas of origin and insertion can easily be reversed here, depending on what attachments of pectoralis major are held in place and which are freely movable. ### All fibers working together Generally speaking, when we’re standing in [anatomical position](https://3dmusclelab.com/anatomical-position/), all fiber sections of pectoralis major work together to do adduction, horizontal adduction (reaching your arm across your body), and medial (internal) rotation. Also, when we’re moving from anatomical position with our arms at our sides, the clavicular fibers assist with flexion of the arm at the shoulder. ### Other actions Because of the broad area of origin, this muscle can do two opposite actions. As I said, the clavicular section can flex the shoulder joint. However, when the shoulder and arm are fixed, pectoralis major contributes to [movements](https://3dmusclelab.com/planes-of-movement/) in a different way. When the other end of the attachments, what we think of as the insertion, is held in place, the available movements are different. If our [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/) is already in a flexed position and has a resistance, and pectoralis major [contracts](https://3dmusclelab.com/muscle-contractions/), the inferior fibers of pec major (the sternal, costal, and abdominal fibers) assist with extension of the flexed arm at the shoulder joint. They assist with pulling it downward. ### Assists with breathing Additionally, because of its specific attachments, when the humerus is in a fixed position, pectoralis major assists with [breathing](https://3dmusclelab.com/muscular-actions-breathing/) as well. When the shoulder is fixed, pec major can assist with inspiration. So, interestingly, we can see that, like several other muscles we’ve explored with multiple fiber sections, pectoralis major can act as an [antagonist](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) to itself. ## Conclusion The pectoralis major muscle is an important muscle for many athletic activities, from weightlifting to swimming to throwing. Many people have a general idea where it’s located. However, its specific structure of multiple myofascial regions arranged in overlapping bands is less well-known. This arrangement contributes to the many different types of actions that this muscle assists with. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Gilroy, A.M., B.R. MacPherson, and J.C. Wikenheiser (Eds.) 2025. Atlas of Anatomy. (5th ed.) Thieme. [Solari, F. and B. Burns. 2023. Anatomy, Thorax, Pectoralis Major. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.](https://www.ncbi.nlm.nih.gov/books/NBK525991/) Travell, J.G. and D.G. Simons. 1999. Chapter 42: Pectoralis Major Muscle and the Subclavius. In Myofascial Pain and Dysfunction – The Trigger Point Manual. Volume 1 (2nd Edition). New York, NY: Lippincott, Williams, and Wilkins Publishing. --- Source: https://3dmusclelab.com/the-pectoralis-minor-muscle/ Author: David Keil · Updated: 2026-09-25 Muscle reference · Shoulder # The Pectoralis Minor Muscle The pectoralis minor is a deep shoulder muscle. You’ll find it in the upper anterior region of the torso, where our shoulder meets our ribcage. It’s deep to (underneath) the larger pectoralis major muscle. ![pectoralis minor muscle](https://3dmusclelab.com/wp-content/uploads/2026/08/pectoralis-minor.jpg) The pectoralis minor muscle is a small pair of muscles with some important functions. Although they don’t get nearly as much press, or attention at the gym, as their larger cousins the [pectoralis major](https://3dmusclelab.com/pectoralis-major/) muscles, they are just as relevant to everyday [functional movements](https://3dmusclelab.com/functional-movement/). In this article, we’ll take a closer look at where the pectoralis minor muscle is located and what actions it’s involved in. Read on to learn more. ## Quick facts Origin · Insertion · Action - **Origin**: Third, fourth, and fifth ribs (some people have a band to the second rib) - **Insertion**: Coracoid process of the scapula - **Action**: **Scapula free:** protraction of the scapula, depression of the scapula, downward rotation of the scapula, stabilizes the scapula to the torso **Scapula fixed:** assists forced inspiration ## Location The pectoralis minor is a deep shoulder muscle. You’ll find it in the upper anterior region of the torso, where our shoulder meets our [ribcage](https://3dmusclelab.com/ribcage/). It’s [deep to (underneath)](https://3dmusclelab.com/anatomical-terms-location-position/) the larger pectoralis major muscle. Like our other shoulder muscles, we have a pair of these little muscles, one on the right and one on the left. Specifically, the pectoralis minor [attaches](https://3dmusclelab.com/muscle-origin-insertion-and-action/) at its superior end to the coracoid process of the [scapula](https://3dmusclelab.com/scapula/). This is the small beak-like projection where our scapula reaches all the way to the front of our body. This [muscle](https://3dmusclelab.com/what-is-a-muscle/) then travels in typically three bands of fibers to attach at its inferior end to the third, fourth, and fifth ribs. However, anatomists have observed anatomical variation in this muscle and found that some people have a band of fiber that attaches to the second rib. In rare cases, anatomists have observed this muscle attached to the first or sixth rib. One important point to note about pectoralis minor’s location is that it travels over the top of the [brachial plexus](https://3dmusclelab.com/brachial-plexus/). This is a bundle of nerves that come out from the lower cervical vertebrae. The brachial plexus includes multiple nerve branches that become the median, ulnar, and other nerves that supply the shoulder and arm. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Pectoralis minor muscle actions The pectoralis minor is a significant muscle for movement, stabilization, and even [breathing](https://3dmusclelab.com/muscular-actions-breathing/). It makes an important connection between the scapula and the ribcage. In movement, when the scapula is free to move, the pectoralis minor muscle moves the scapula toward its inferior attachment on the third, fourth, and fifth ribs. Pectoralis minor is a small muscle, however, and can assist with different movements depending on which [agonists](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) it’s working with. Pectoralis minor can assist with protraction of the scapula and depression of the scapula. Depending on the position of the arm and torso, pectoralis minor can also assist with [downward rotation](https://3dmusclelab.com/anatomical-terms-for-movements/) of the scapula and help stabilize the scapula to the torso. When the scapula is fixed and not free to move, the pectoralis minor muscle can assist with the action of respiration. Specifically, it can assist with forced inspiration by contributing to lifting and expanding the ribs that it is attached to. ### Posture and the pectoralis minor A short pectoralis minor can create significant resistance to allowing the scapula to return to and rest in a neutral position. Because the pectoralis minor contributes to moving the scapula, and the glenoid fossa of the [shoulder](https://3dmusclelab.com/shoulder-joint-in-movement/) (the socket of the shoulder [joint](https://3dmusclelab.com/synovial-joint/)) is a depression in the scapula, this small muscle affects [shoulder position](https://3dmusclelab.com/shoulder-girdle/). It’s related to the shoulder position we so often see, that is, shoulders habitually pulled down and in medially. ### Other considerations As I described above, the pectoralis minor runs over the brachial plexus, which includes the nerves that feed the shoulder and arm. A short, tight pectoralis minor can compress the neurovasculature and cause a variety of nerve, artery, and/or vein-related compression symptoms, depending on which structures are compressed. The axillary region in the body includes a complex intersection of many structures that can impact the brachial plexus, but a short, tight pectoralis minor is one structure that can contribute to nerve-compression symptoms. ## Conclusion The pectoralis minor is a small but significant muscle on the upper anterior portion of our chest. It’s a deep muscle that contributes to balanced shoulder and arm position. In situations of particularly strong inhales, it can even assist with respiration. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Chaitow, L. and J. DeLany. 2011. Chapter 13: Shoulder, Arm, and Hand. In Clinical Application of Neuromuscular Techniques. Volume 1 (Second Edition). New York, NY: Churchill Livingstone Publishing. Gilroy, A.M., B.R. MacPherson, and J.C. Wikenheiser (Eds.) 2025. Atlas of Anatomy. (5th ed.) Thieme. [Travell, J.G. and D.G. Simons. 1999. Chapter 43: Pectoralis Minor Muscle. In Myofascial Pain and Dysfunction – The Trigger Point Manual. Volume 1 (2nd Edition). New York, NY: Lippincott, Williams, and Wilkins Publishing.](https://bookshop.org/p/books/travell-simons-donnelly-s-myofascial-pain-and-dysfunction-the-trigger-point-manual-cesar-fernandez-de-las-penas-ph-d-md/01780a6de8cada8c?ean=9781975223113&bkshp-astro=t) --- Source: https://3dmusclelab.com/pelvic-floor-muscles/ Author: David Keil · Updated: 2026-09-09 Muscle reference · Pelvis # The Pelvic Floor Muscles The pelvic floor is the soft tissue that collectively fills the bowl-shaped space between the bones and forms the base of the pelvis. The pelvic floor is also called the pelvic diaphragm. The group includes four muscles: the puborectalis, pubococcygeus, iliococcygeus, and the coccygeus. ![Pelvic Floor Muscles](https://3dmusclelab.com/wp-content/uploads/2026/07/pelvic-floor-muscles.jpg) The idea of an anatomic pelvic floor has been in the media a lot lately as more people recognize the importance of this group of muscles. People who have experienced pregnancy are likely already familiar with their pelvic floor muscles. An aging population grappling with common [age-related](https://3dmusclelab.com/muscles-when-we-age/) issues, like incontinence, is becoming more acquainted with the relevance of their pelvic floor muscles. Pelvic floor therapies have become more commonly available for these populations and others. And as more people investigate the role of connecting their core to their health and wellness, the pelvic floor muscles come up again. So what and where are these muscles? In this article, we’ll explore exactly that. Read on to find out. ## Quick facts Origin · Insertion · Action - **Origin**: **Puborectalis:** back of the pubic bone on either side of the pubic symphysis **Pubococcygeus:** back of the pubic bone on either side of the pubic symphysis, lateral to the puborectalis attachment **Iliococcygeus:** internal obturator fascia **Coccygeus:** ischial spine - **Insertion**: **Puborectalis:** the two sides curve back to form a continuous U-shaped band that loops behind the rectal hiatus **Pubococcygeus:** anococcygeal ligament and the coccyx **Iliococcygeus:** anococcygeal ligament and coccyx **Coccygeus:** inferior sacrum and coccyx - **Action**: **All pelvic floor muscles:** support, preventing the viscera from dropping or protruding out of the body Levator ani (puborectalis, pubococcygeus, iliococcygeus): maintaining urinary and bowel continence **Coccygeus:** flexion of the coccyx ## The Pelvic Floor Muscles The pelvic floor is the soft tissue that collectively fills the bowl-shaped space between the bones and forms the base of the pelvis. The pelvic floor is also called the pelvic diaphragm because the combined muscles of the pelvic floor form a sheet of connective tissue that creates a partition for the viscera above it. The group of muscles that work together to create the pelvic floor includes four muscles. They are the puborectalis, pubococcygeus, iliococcygeus, and the coccygeus. Three of those muscles are further subgrouped together based on their function. Those three, the puborectalis, pubococcygeus, and iliococcygeus, are collectively referred to as the levator ani muscle group. There are, of course, other muscles that attach to the [pelvis](https://3dmusclelab.com/exploring-the-pelvis/) and affect the tone of the pelvic connective tissue as a whole. But those muscles, like the [piriformis](https://3dmusclelab.com/piriformis-muscle/) and [obturator internus](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/), are primarily considered muscles of the [hip joint](https://3dmusclelab.com/exploring-the-hip-joint/), so we won’t cover them further here. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Location Although the three levator ani muscles and coccygeus work together, they each have specific attachments. ### Puborectalis Puborectalis attaches to the back of the pubic bone on either side of the pubic symphysis, then the two sides curve back and around to create a continuous U-shaped band of tissue that loops behind the rectal hiatus. ### Pubococcygeus Pubococcygeus also attaches to the back of the pubic bone on either side of the pubic symphysis, but its [attachment](https://3dmusclelab.com/muscle-origin-insertion-and-action/) is lateral to the puborectalis attachment on each side. Both the right and left sides of the pubococcygeus then attach to the anococcygeal [ligament](https://3dmusclelab.com/ligaments-and-tendons/) and the coccyx. ### Iliococcygeus The iliococcygeus attaches to the internal obturator [fascia](https://3dmusclelab.com/what-is-connective-tissue/) and then attaches at the other end to the anococcygeal ligament and coccyx, along with the pubococcygeus. ### Coccygeus The coccygeus [muscle](https://3dmusclelab.com/what-is-a-muscle/) runs in a more medial to lateral direction than the levator ani group of muscles, which run in a more anterior to posterior direction. There are right and left sides of this muscle as well. Each side attaches to the ischial spine and then attaches at the other end to the inferior sacrum and coccyx. ## Pelvic floor muscle actions ### Support All of the muscles of the pelvic floor primarily work together in their function. The function of the pelvic floor, or pelvic diaphragm, is, like other diaphragms in our body, to keep certain things corralled in a particular space. In this case, the pelvic floor prevents our viscera, that is, our [abdominal](https://3dmusclelab.com/abdominal-muscles/) and pelvic organs and their associated structures, from dropping or protruding out of our body. ### Elimination The name of the group of three levator ani muscles (puborectalis, pubococcygeus, and iliococcygeus) gives us a clue to another function of the pelvic floor muscles. Levator is from the Latin levare, which means to lift. And ani comes from anus, the Latin for ring, and of course, refers to the anus. So, these muscles are important for maintaining urinary and bowel continence. These muscles relax or [contract](https://3dmusclelab.com/muscle-contractions/) depending on where we are in the cycle of elimination. ### Movement of the tailbone Although movements at the coccyx itself are small, the coccygeus muscle also contributes to [flexion](https://3dmusclelab.com/anatomical-terms-for-movements/) of the coccyx. ## Conclusion The pelvic floor muscles have important supportive functions as well as muscular actions. Healthy tone in this muscle group provides essential support for our organs above. Contraction and relaxation of these muscles are necessary for healthy urinary and bowel continence. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References Gilroy, A.M., B.R. MacPherson, and J.C. Wikenheiser (Eds.) 2025. Atlas of Anatomy. (5th ed.) Thieme. [Raizada V. and R.K. Mittal. 2008. Pelvic floor anatomy and applied physiology. Gastroenterol Clin North Am. 37(3):493-509.](https://pmc.ncbi.nlm.nih.gov/articles/PMC2617789/) --- Source: https://3dmusclelab.com/piriformis-muscle/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Hip # What And Where Is The Piriformis Muscle? Piriformis is a pear-shaped muscle that’s located underneath the big gluteus maximus on the buttocks. It’s one of a group of six muscles that work together called the deep six lateral rotators of the hips. ![The Piriformis Muscle](https://3dmusclelab.com/wp-content/uploads/2019/01/piriformis-muscle.png) Many people have heard of the piriformis muscle because they’ve heard of piriformis syndrome or they’ve heard that the muscle can be associated with sciatica-like pain. But, what exactly is the piriformis muscle? ## Quick facts Origin · Insertion · Action - **Origin**: Anterior sacrum - **Insertion**: Superior portion of the greater trochanter - **Action**: Externally/laterally rotates the femur at the hip joint (anatomical position), abducts the femur at the hip joint (hip flexed to 90°), internally rotates the femur at the hip joint (hip flexed at least 60° up to full flexion) ## Where is the piriformis muscle located? Piriformis is a pear-shaped muscle that’s located underneath the big gluteus maximus on the buttocks. It’s one of a group of six muscles that work together called the [deep six lateral rotators](https://3dmusclelab.com/deep-six-lateral-rotator-muscles/) of the hips. ### Origin The piriformis originates on the anterior sacrum. ### Insertion The piriformis inserts on the superior portion of the greater trochanter, which is a bony protrusion on the top of the femur or thigh bone. An important fact about the location of the piriformis muscle is its location in relationship to the sciatic nerve. Most commonly, the piriformis is located just superior to the sciatic nerve. Different orientations are also possible where some or all of the sciatic nerve runs through the piriformis, which can be one contributing factor to piriformis syndrome. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What actions does the piriformis muscle do? When we start describing the actions of the piriformis, things get a little tricky. This is because these actions depend on the position of the hip. If the body is in anatomical position, then the movement of the piriformis is pretty straightforward. In that case, the piriformis muscle acts to: - Externally/laterally rotate the femur (thigh) at the hip joint. Things get a little more complicated when we move out of anatomical position. When we flex the hip joint, we change the line of tension between the sacrum and the greater trochanter. Current research (Chaitow and DeLaney, 2011; Travell and Simon, 1993) suggests that: When the hip joint is flexed to 90°, the piriformis can act to: - Abduct the femur at the hip joint. And when the hip joint is flexed at least 60° and up to full flexion, the piriformis can act to: - Internally rotate the femur at the hip joint. If you want to learn more about the piriformis muscle, check out the related article in this series: [What Is Piriformis Syndrome?](https://3dmusclelab.com/piriformis-syndrome/) Oh, and by the way, we cover it in our online course! The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ### References Chaitow, L. and J. DeLany. 2011. The Hip. *In* Clinical Application of Neuromuscular Techniques. Volume 2 (Second Edition). Travell, J.G. and D.G. Simons. 1993. Piriformis and Other Short Lateral Rotators. *In* Myofascial Pain and Dysfunction —The Trigger Point Manual. Volume 2. --- Source: https://3dmusclelab.com/gastrocnemius-soleus-plantaris/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Lower leg # The Posterior Compartment: Gastrocnemius, Soleus, And The Plantaris The muscles of the superior posterior compartment form what we think of as our "calf muscles." The main muscles that the compartment includes are the gastrocnemius and soleus muscles. There is also a small, thin muscle called plantaris that is part of this section. ![Gastrocnemius And Soleus Muscles](https://3dmusclelab.com/wp-content/uploads/2023/12/soleus-gastroc-muscle.jpg) Our [lower leg muscles](https://3dmusclelab.com/tibialis-anterior-fibularis-longus/) often don’t get as much attention as the quadriceps and [hamstrings](https://3dmusclelab.com/anatomy-of-the-hamstrings/) of our thigh. That is, they don’t get our attention until something starts to hurt. But we use these muscles for running, jumping, walking, and for simply standing upright. In this article, let’s take a look at our posterior lower leg muscles, their attachments, and their actions. ## Quick facts Origin · Insertion · Action - **Origin**: **Gastrocnemius:** medial head: medial condyle of the femur; lateral head: lateral condyle of the femur **Soleus:** soleal line on the tibia and the proximal end of the fibula **Plantaris:** supracondylar line on the femur - **Insertion**: **Gastrocnemius:** calcaneus, via the Achilles tendon **Soleus:** calcaneus, via the Achilles tendon **Plantaris:** calcaneus, via the Achilles tendon - **Action**: **Gastrocnemius:** flex the knee joint, plantarflexion of the foot at the ankle **Soleus:** plantarflexion of the foot at the ankle **Plantaris:** flexion of the knee, plantarflexion of the foot at the ankle (if present) ## What is the posterior compartment? The lower leg is typically divided into three main muscular compartments. Those are the anterior, lateral, and posterior compartments. Sometimes anatomists include a fourth compartment. They divide the posterior compartment into the superficial and deep posterior compartments. Those compartments are divided structurally by intermuscular septa. Those are areas of [fascia between the muscles](https://3dmusclelab.com/what-is-muscle-fascia/). The superficial posterior compartment is the section of the back of the lower leg that is closer to the surface. It’s separated from the deep posterior compartment by the posterior intermuscular septum. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What are the key muscles of the posterior compartment? The muscles of the superficial posterior compartment form what we think of as our “calf muscles.” The main muscles that the compartment includes are the gastrocnemius and soleus muscles. There is also a small, thin muscle called plantaris that is part of this section. However, it’s very small, mostly tendinous, and absent in about 10% of the population. When anatomists reference to this group of muscles, they sometimes refer to them as the “triceps surae.” This is a more technical name for the group of these three muscles. ## Muscle attachments ### Gastrocnemius The gastrocnemius is the most superficial of the muscles in the posterior compartment of the leg. At the proximal (top) end, it has two heads. The medial head [attaches](https://3dmusclelab.com/muscle-origin-insertion-and-action/) to the medial condyle of the femur (the thigh bone). The lateral head attaches to the lateral condyle of the femur. From there the two heads join to become one muscle. At the distal end, they become the Achilles [tendon](https://3dmusclelab.com/ligaments-and-tendons/), which attaches to the heel bone (called the calcaneus). ### Soleus The Soleus is located deep to (underneath) the gastrocnemius. At its proximal end, it attaches to a bony ridge called the “soleal line” on the tibia and to the proximal end of the fibula (the smaller of the two leg bones). At its distal (lower) end, it joins with gastrocnemius to become the Achilles tendon which attaches to the calcaneus. ### Plantaris The small plantaris attaches at its proximal end to a bony ridge on the femur called the supracondylar line. The tendinous portion of this muscle then runs between the gastrocnemius and soleus. It joins those two muscles at its distal end to become part of the Achilles tendon and attach to the calcaneus. ## Muscle actions The gastrocnemius crosses two [joints](https://3dmusclelab.com/synovial-joint/). It crosses and acts on both the knee and ankle joints. At the proximal end, the gastrocnemius could be thought of as “holding hands” with the lower fibers of the hamstrings. They work together to flex the knee joint. At its distal end, it works with the soleus to do plantarflexion of the foot at the ankle. In [functional movement](https://3dmusclelab.com/functional-movement/), one job of the gastrocnemius and soleus muscles is to work with the quadriceps to coordinate our leg and foot movements during the swing phase of [gait](https://3dmusclelab.com/what-is-the-gait-cycle/). They also help maintain our static posture when we’re standing. The little plantaris crosses both [the knee](https://3dmusclelab.com/knee-joint/) and [ankle joints](https://3dmusclelab.com/exploring-the-ankle-joint/) as well. If it’s present, it assists in both flexion of the knee and plantarflexion of the foot at the ankle. ## Conclusion Our posterior lower leg [muscles](https://3dmusclelab.com/what-is-a-muscle/) are an important group for running, jumping, and walking. They’re important muscles for creating power behind those movements, particularly when we’re going uphill. They sometimes get overshadowed by the more popular thigh muscles, like our quadriceps and hamstrings. But, they’re just as important. In this article, we reviewed their location, attachments, and actions. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bordoni B. and M. Varacallo. 2023. Anatomy, Bony Pelvis and Lower Limb, Gastrocnemius Muscle. [Updated 2023 Apr 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532946/](https://www.ncbi.nlm.nih.gov/books/NBK532946/) [Myers, T., 2014. ‘Calf x Fascia: The compartments of the lower leg’ In The Anatomist’s Corner: Issues in Structural Anatomy. Pgs.171-177.](https://www.anatomytrains.com/product/the-anatomists-corner/) --- Source: https://3dmusclelab.com/quadratus-lumborum-muscle/ Author: David Keil · Updated: 2026-05-21 Muscle reference · Back # The Quadratus Lumborum Muscle The quadratus lumborum, or QL for short, is actually two muscles. We have one on the right side of our body and one on the left. These two muscles lie deep within our body along the lumbar spine. ![Quadratus Lumborum Muscle](https://3dmusclelab.com/wp-content/uploads/2026/02/quadratus-lumborum.jpg) The quadratus lumborum muscle is a unique part of our core. It’s an essential part of what connects our lower body to our upper body. It’s a necessary part of twisting, bending, and walking. Despite its important contributions to both [static posture](https://3dmusclelab.com/anatomical-terms-location-position/) and [functional movement](https://3dmusclelab.com/functional-movement/), people are often unaware of where this muscle is located and unclear on exactly what it does. Read on for an introduction to the quadratus lumborum [muscle](https://3dmusclelab.com/what-is-a-muscle/). ## Quick facts Origin · Insertion · Action - **Origin**: **Vertical fibers:** crest of the ilium and the iliolumbar ligament **Ilium diagonal fibers:** crest of the ilium **Rib diagonal fibers:** transverse processes of the lumbar vertebrae, almost always including L2, L3, and L4 - **Insertion**: **Vertical fibers:** 12th rib **Ilium diagonal fibers:** transverse processes of the lumbar vertebrae, typically L1-L4 **Rib diagonal fibers:** 12th rib - **Action**: **Unilateral:** lateral pelvic tilt (hip hiking), lateral flexion of the lumbar spine **Bilateral:** may contribute to extending the lumbar spine **Main action:** stabilization of the lumbar spine, sacrum, and sacroiliac joints ## Location The quadratus lumborum, or QL for short, is actually two muscles. We have one on the right side of our body and one on the left. The name quadratus refers to the roughly square-shaped structure of this muscle, although it’s really more of a rectangle in most people. These two muscles lie deep within our body along the lumbar spine, which is what the name lumborum refers to. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Quadratus lumborum muscle attachments Each of these two muscles has at least three distinct sets of fibers. There is one set of fibers that runs vertically from the crest of the ilium and the iliolumbar ligament to the [12th rib](https://3dmusclelab.com/ribcage/). A second set of fibers runs at a diagonal from the crest of the ilium to the transverse processes of the lumbar vertebrae. Those fibers typically attach to L1-L4, but there is variation from person to person. Finally, there is a third set of fibers that run diagonally from the 12th rib to the transverse processes of the lumbar vertebrae. References vary on which specific lumbar vertebrae these fibers connect to, which highlights the variation in these [attachments](https://3dmusclelab.com/muscle-origin-insertion-and-action/) between individuals in the population. These fibers may, in some people, connect to the transverse processes of any of the lumbar vertebrae from L1-L5, but almost always include an attachment to L2, L3, and L4. ## Muscle actions of the QL Our quadratus lumborum muscles can act unilaterally, meaning one QL acts separately and differently from the other. Or, both QL can work together bilaterally, meaning that both QL are contributing to the same action. Additionally, as I’ve just explained, the quadratus lumborum has multiple fiber directions. So, like other muscles with multiple lines of pull, different sets of fibers within the QL can potentially contribute to different actions. For these reasons, although our quadratus lumborum muscles are small, we can feel the effects of their contraction or resistance when twisting, side-bending, bending forward, and bending backward. When acting unilaterally, our quadratus lumborum muscles can concentrically contract to contribute to lateral pelvic tilt (commonly called hip hiking) and lateral flexion of the lumbar spine. When acting bilaterally, they may contribute to extending the lumbar spine, but some anatomists suggest the QL muscles don’t create enough [concentric force](https://3dmusclelab.com/muscle-contractions/) to be significantly involved in that action. Anatomists do agree that these muscles generally don’t create a lot of concentric force. For that reason, their main action is stabilization and [working with other muscles](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) to stabilize, create, or resist movement. The quadratus lumborum muscles contribute to the stabilization of the lumbar spine, sacrum, and [sacroiliac joints](https://3dmusclelab.com/sacroiliac-joint/). ### Relates the lower body and the upper body Because this muscle is so central, it’s relevant to most kinds and directions of movement, and it is intimately related to the rest of the core of the body. It’s an essential part of relating the upper body to the lower body through its connections between the ribcage and [spine](https://3dmusclelab.com/exploring-the-spine/) to the [pelvis](https://3dmusclelab.com/exploring-the-pelvis/). QL is one of several muscles that may respond by tightening as part of a larger compensatory strain pattern when there are patterns in the lower body that the upper body is adapting to, for example, a leg length difference. For similar reasons, QL may be part of back pain problems. However, back pain is complex and commonly does not have a single source. ### Affects breathing Finally, our quadratus lumborum muscles are related to [breathing actions](https://3dmusclelab.com/muscular-actions-breathing/). Our QL muscles contribute to the position and stabilization of the 12th rib, which affects the support for the diaphragm. Additionally, some QL fibers are continuous with some fibers of the diaphragm and therefore have a more direct relationship on breathing. ## Conclusion The quadratus lumborum is a deep core muscle that runs along our lumbar spine and connects both to our 12th rib and the ilium of our pelvis. Its central location and multiple fiber directions mean that it affects a wide range of movements. Its action is essential for maintaining balanced static posture and for functional [movements](https://3dmusclelab.com/anatomical-terms-for-movements/) like [walking](https://3dmusclelab.com/what-is-the-gait-cycle/). The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bordoni, B., R.E. Sina, M.A. Varacallo. 2025. Anatomy, Abdomen and Pelvis, Quadratus Lumborum. [Updated 2024 Jul 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535407/](https://www.ncbi.nlm.nih.gov/books/NBK535407/) Chaitow, L. and J. DeLany. 2011. Chapter 10: The Lumbar Spine. In Clinical Application of Neuromuscular Techniques – The Lower Body. Volume 2 (Second Edition). New York, NY: Churchill Livingstone Publishing. --- Source: https://3dmusclelab.com/quadriceps-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Thigh # This is where you enter the title of the new post The quadriceps muscles are a powerful part of both our movement and posture. When you combine all four of the quadriceps muscles together you have the largest group of muscles by volume in the body as well as the strongest group of muscles. They are four distinct muscles throughout most of their length that merge into a single tendinous attachment at the distal end. ![Quadriceps Muscles](https://3dmusclelab.com/wp-content/uploads/2025/02/quadriceps-muscle-h.jpg) The quadriceps [muscles](https://3dmusclelab.com/what-is-a-muscle/) are a popular group, for good reason. These muscles are a powerful part of both our movement and posture. When you combine all four of the quadriceps muscles together you have the largest group of muscles by volume in the body as well as the strongest group of muscles. Because they are superficial, meaning close to the surface, people are often familiar with the general location and action of these muscles. In this article, we’ll help you get a little more specific. You’ll learn where the quadriceps attach and understand how they come together to create movement. ## Quick facts Origin · Insertion · Action - **Origin**: **Rectus femoris:** anterior inferior iliac spine of the pelvis and the supraacetabular groove **Vastus lateralis:** intertrochanteric line of the femur, greater trochanter, gluteal tuberosity, and the lateral lip of the linea aspera of the femur **Vastus medialis:** intertrochanteric line, pectineal line of the femur, medial lip of the linea aspera, medial supracondylar line, medial aspect of the femoral shaft **Vastus intermedius:** anterior and lateral surfaces of the femoral shaft - **Insertion**: **All four muscles:** patella via the quadriceps tendon, continuing to the tibial tuberosity of the tibia via the patellar ligament - **Action**: **Rectus femoris:** extension of the knee joint, hip flexion **Vastus lateralis:** extension of the knee joint **Vastus medialis:** extension of the knee joint **Vastus intermedius:** extension of the knee joint ## What muscles are included in this group? These muscles are sometimes referred to collectively as the quadriceps femoris muscle. However, they are really four distinct muscles throughout most of their length that merge into a single [tendinous attachment](https://3dmusclelab.com/ligaments-and-tendons/) at the distal end. Each of the muscle sections is typically referred to by its individual muscle name. The four muscles in this group include: - Rectus femoris - Vastus lateralis - Vastus medialis - Vastus intermedius There is some variability in muscle morphology between individuals, however. Although the typical quadriceps has four muscle bellies (hence the name), some people have more than four muscle bellies making up the muscle group on their anterior thigh. ![Quadriceps Muscles](https://3dmusclelab.com/wp-content/uploads/2025/02/quadriceps-muscle.jpg) ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Quadriceps muscle attachments Among the four muscles in this group, rectus femoris is the most superficial muscle. It lies over the top of part of vastus lateralis, part of vastus medialis, and all of vastus intermedius. Vastus intermedius lies between vastus lateralis and vastus medialis. Rectus femoris is the only one of the quadriceps that crosses the [hip joint](https://3dmusclelab.com/exploring-the-hip-joint/). ### Proximal attachments Specifically, rectus femoris attaches at its proximal end to the anterior inferior iliac spine of the [pelvis](https://3dmusclelab.com/exploring-the-pelvis/) and the supraacetabular groove. The other three of the four [muscles attach](https://3dmusclelab.com/muscle-origin-insertion-and-action/) to various locations on the femur at their proximal ends. At its proximal end, vastus medialis attaches to the intertrochanteric line, pectineal line of the femur, medial lip of the linea aspera, medial supracondylar line of the femur, and the medial aspect of the femoral shaft. Vastus lateralis also has several attachments at its proximal end. They include the intertrochanteric line of the femur, greater trochanter, gluteal tuberosity, and the lateral lip of the linea aspera of the femur. Finally, the last of the quadriceps, vastus intermedius attaches to the anterior and lateral surfaces of the femoral shaft at its proximal end. ### Distal attachments All four muscles merge into a single tendinous attachment at the distal end just before they attach to the patella via the quadriceps tendon. They then continue on to attach to the tibial tuberosity of the tibia via the patellar ligament. ## Actions of the quadriceps muscles All four of these muscles are primary extenders of the [knee joint](https://3dmusclelab.com/knee-joint/). One, rectus femoris also contributes to hip flexion. It’s the most superficial of the muscles that flex the hip, so it often functions in activities like yoga as a restrictor to hip extension (such as in back bending) in addition to doing hip flexion. The combined [action](https://3dmusclelab.com/muscle-contractions/) of the four quadriceps muscles is essential for all [movement](https://3dmusclelab.com/functional-movement/) of the kinetic chain of the lower limb. That includes activities like [walking](https://3dmusclelab.com/what-is-the-gait-cycle/), running, climbing stairs, playing just about any sport, and getting up and down from the floor, a chair, or the car. Because the four quadriceps muscles form the quadriceps tendon which lies over the patella, the balance of tension between these four muscles is also important for stabilization and [tracking of the patella](https://3dmusclelab.com/valgus-and-varus-knee-pain/) in the knee. Additionally, the quadriceps muscles contribute to maintaining our posture. ## Conclusion The quadriceps are large powerful muscles that are essential for everyday movement as well as sports and athletic activities. A clearer understanding of where each of these muscles attach and what [joints](https://3dmusclelab.com/synovial-joint/) they cross can help you better understand why they influence the specific types of movement that they do. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Bordoni, B. and M.A. Varacallo. 2025. Anatomy, bony pelvis and lower limb: Thigh quadriceps muscle. [Updated 2023 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513334/](https://www.ncbi.nlm.nih.gov/books/NBK513334/) Chaitow, L. and J. DeLany. 2011. Chapter 13: The Knee. In Clinical Application of Neuromuscular Techniques. Volume 2 – The Lower Body (Second Edition). New York, NY: Churchill Livingstone Publishing. [Olewnik, L. K. Ruzik, B. Szewczyk, M. Podgórski, P. Aragonés, P. Karauda, R.S. Tubbs, J. R. Sanudo, M.B. Pires, M. Polguj. 2022. The relationship between additional heads of the quadriceps femoris, the vasti muscles, and the patellar ligament. Biomed Res Int. Feb 16:9569101.](https://pmc.ncbi.nlm.nih.gov/articles/PMC8866009/) --- Source: https://3dmusclelab.com/rotator-cuff-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Shoulder # What And Where Are The Rotator Cuff Muscles? The rotator cuff muscles are a group of four muscles that come together and attach via a common tendon to the humerus (our upper arm bone). They include supraspinatus, infraspinatus, teres minor, and subscapularis. This group of muscles all go from an attachment on the scapula to an attachment on the humerus and cross the glenohumeral joint (the shoulder joint). ![The Rotator Cuff Muscles](https://3dmusclelab.com/wp-content/uploads/2020/05/Rotator-cuff_fi.jpg) ### Infraspinatus ![Infraspinatus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/infraspinatus-mus.jpeg) ### Teres minor ![Teres Minor Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/teres-minor-mus.jpeg) ### Subscapularis ![Subscapularis Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/subscapularis-mus.jpeg) ### Supraspinatus ![Supraspinatus Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/supraspinatus-mus.jpeg) The rotator cuff muscles are a group of four muscles that come together and attach via a common tendon to the humerus (our upper arm bone). They include supraspinatus, infraspinatus, teres minor, and subscapularis. You can use the acronym SITS to help remember each of the muscles in this group. This group of muscles all go from an attachment on the scapula to an attachment on the humerus and cross the glenohumeral joint ([the shoulder joint](https://3dmusclelab.com/shoulder-girdle/)). The tendinous attachment of these four muscles on the humerus resembles a shirt cuff, which is where the group of muscles gets its name, the rotator cuff. ## Quick facts Origin · Insertion · Action - **Origin**: **Supraspinatus:** supraspinous fossa of the scapula **Infraspinatus:** infraspinous fossa of the scapula **Teres minor:** lateral portion of the dorsal side of the scapula **Subscapularis:** subscapular fossa of the scapula - **Insertion**: **Supraspinatus:** greater tubercle of the humerus (superior facet) **Infraspinatus:** greater tubercle of the humerus (middle facet) **Teres minor:** greater tubercle of the humerus (lower facet) **Subscapularis:** lesser tubercle of the humerus - **Action**: **Supraspinatus:** initiates abduction of the humerus **Infraspinatus:** lateral rotation of the humerus **Teres minor:** lateral rotation of the humerus **Subscapularis:** medial rotation of the humerus ## Where are the rotator cuff muscles located? The four rotator cuff muscles each originate from a different location on the scapula and then insert on either the greater or lesser tubercle of the humerus. Let’s look at the origin and insertion for each of these muscles one at a time. ### Origins Supraspinatus: supraspinous fossa of the scapula Infraspinatus: infraspinous fossa of the scapula Teres minor: lateral portion of the dorsal side of the scapula Subscapularis: subscapular fossa of the scapula ### Insertions Supraspinatus: greater tubercle of the humerus (superior facet) Infraspinatus: greater tubercle of the humerus (middle facet) Teres minor: greater tubercle of the humerus (lower facet) Subscapularis: lesser tubercle of the humerus ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What actions do the rotator cuff muscles do? Supraspinatus: initiates abduction of the humerus Infraspinatus: lateral rotation of the humerus Teres minor: lateral rotation of the humerus Subscapularis: medial rotation of the humerus One of the most important actions that all four of the rotator cuff muscles contribute to is stabilization of the shoulder joint. These four muscles all contribute to keeping the head of the humerus in the right place within the glenoid fossa, the “socket” of the shoulder ball and socket joint. If you want to learn more about the rotator cuff muscles or the [shoulder joint](https://3dmusclelab.com/shoulder-girdle/), they are covered in our online course. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/trapezius-muscle/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Back # What And Where Is The Trapezius Muscle? The trapezius is a large, broad muscle on the back. It’s really more like three muscles as it can be divided into sections based on fiber direction and main actions. It’s typically divided into an upper, middle, and lower section. ![Trapezius Muscle](https://3dmusclelab.com/wp-content/uploads/2019/02/trapezius-mus.jpeg) The trapezius is a large, broad muscle on the back. It’s really more like three muscles as it can be divided into sections based on fiber direction and main actions. It’s typically divided into an upper, middle, and lower section. Trapezius is an important muscle to know as it can be relevant to one of the activities we all spend a lot of time doing: sitting in front of the computer! The common [posture for computer users](https://3dmusclelab.com/trapezius-computer-posture/) can shorten the upper trapezius and cause headaches and other symptoms. ## Quick facts Origin · Insertion · Action - **Origin**: **Upper section:** base of the occiput, the ligamentum nuchae, and the spinous processes of vertebrae C1-C7 **Middle section:** spinous processes of vertebrae C7-T3 **Lower section:** spinous processes of vertebrae T4-T12 - **Insertion**: **Upper section:** lateral clavicle and the acromion process **Middle section:** spine of the scapula **Lower section:** root of the spine of the scapula - **Action**: **Upper section:** upward rotation of the scapula, elevates the scapula, laterally flexes the head to the same side if the shoulder is held in place **Middle section:** upward rotation of the scapula, retracts or adducts the scapula **Lower section:** upward rotation of the scapula, depresses the scapula ## Where is the trapezius muscle located? Trapezius is a large muscle with many places of attachment. Sections of the trapezius muscle can even work in opposition to each other. To understand how that can happen, we need to see where trapezius attaches, so let’s take a look at the specific attachments for each section of the trapezius muscle. ### What is the origin of the trapezius? The upper section of trapezius originates on the base of the occiput, the ligamentum nuchae, and the spinous processes of vertebrae C1-C7. The middle section of trapezius originates on the spinous processes of vertebrae C7-T3. The lower section of trapezius originates on the spinous processes of vertebrae T4-T12. ### What is the insertion of the trapezius? The upper section of trapezius inserts on the lateral clavicle and the acromion process. The middle section of trapezius inserts on the spine of the scapula. The lower section of trapezius inserts on the root of the spine of the scapula. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What actions does the trapezius muscle do? All three sections of the trapezius muscle contribute to upward rotation of the scapula. They can also help stabilize the scapula. Each of the three sections of trapezius also contributes to another movement that the other sections of the muscle don’t do. The sections of trapezius can function independently of one another. The upper section of trapezius elevates the scapula. It can also laterally flex the head to the same side if the shoulder is held in place. The middle section of trapezius retracts or adducts the scapula. The lower section of trapezius depresses the scapula. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) --- Source: https://3dmusclelab.com/muscles-when-we-age/ Author: David Keil · Updated: 2025-12-17 Muscles # What Happens To Muscles When We Age? ![Muscles and Aging](https://3dmusclelab.com/wp-content/uploads/2025/07/muscle-aging.jpg) Aging is an inevitable part of life. Hopefully, we’re around long enough to experience the aging process. However, the slow decline of our bodies is not usually a welcome change. We might feel stiffer, slower, or less balanced as we get into our older years. But what’s actually happening to our muscles and bones when we experience these age-related changes? In a two-part series, we’ll take a closer look at what happens to our body structures as we get older. In this first article, we’ll look at what happens to our muscles as we age. ## What is a muscle? Remember that at the micro level, skeletal [muscle](https://3dmusclelab.com/what-is-a-muscle/) cells are composed of two proteins, actin and myosin. Those individual cells are wrapped in layers of fascia, which are bundled together and wrapped in [fascia](https://3dmusclelab.com/what-is-muscle-fascia/) again. Those bundles are grouped again and bundled in fascia. When those two proteins in a muscle cell are chemically stimulated to move towards each other, that cell contracts. When a bunch of muscle cells contract, we have the kind of muscle activity that we’re familiar with. ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## What do our muscles do? [Muscle contraction](https://3dmusclelab.com/muscle-contractions/) has critically important functions in our body in addition to the obvious one of [moving us around](https://3dmusclelab.com/what-is-the-gait-cycle/). Muscle activation shapes and stabilizes our static body posture and is part of what drives our [respiratory function](https://3dmusclelab.com/muscular-actions-breathing/). Skeletal muscle contractions also produce heat and have a role in regulating our body temperature, especially in response to cold. [Muscle activity](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) contributes to maintaining a healthy metabolism of the food we take in and to balancing our protein synthesis with protein breakdown. Skeletal muscle activity is even involved in our immune system response. ## How do muscles change as we age? We experience changes in multiple body systems that affect our muscles as we age. Our tissue itself changes, and we also experience metabolic and nervous system changes that affect our muscles. Changes happen at the cellular level that result in both structural and functional changes we experience at the macro level. Because increasing inactivity often goes along with unavoidable age-related changes, researchers have difficulty separating the specific effects of aging from those of inactivity. What does seem clear is that as we age, we experience a decline in skeletal muscle mass, strength, and tone. When we lose muscle mass, either due to the aging process or to reduced activity levels, it is replaced more slowly as we get older. The quality of our tissue also changes. It becomes more fibrous. Additionally, as lean muscle mass decreases, it is often replaced with more fat tissue. However, when it comes to muscle strength, some amount of that loss may be related to the decrease in activity that often happens along with aging. ### Muscle tissue changes Specifically, during the aging process, the number of our individual muscle fibers decreases, and these fibers also get smaller. Our muscle tissue also tends to lose what are called type 2, or fast twitch fibers. Aging affects our ability to both synthesize and break down protein, which may be part of what causes the reduction in muscle mass and increase in weakness. Hormone levels also affect muscle synthesis and metabolism which causes some of the changes that we experience as we age. Additionally, the contractibility of our muscle tissue decreases as a result of changes in our nervous system. Research differs on exactly when age-related changes start occurring in muscle tissue, but an estimate is possibly as early as after age 30, likely after 40, and at a higher rate of decline after 60. If age-related muscle atrophy becomes very significant and impairs our ability to function, it’s called sarcopenia. However, researchers and medical professionals differ in their opinions of what is officially considered sarcopenia, and when the changes are simply considered age-related decline. ## Why do age-related muscular changes matter? Reduced function in our muscle tissue can have many consequential effects. Less muscle tone, strength, and contractibility can increase the likelihood of falling as well as other kinds of injuries. Additionally, changes to the muscular system can result in declining balance. Muscle health is also related to [bone health](https://3dmusclelab.com/bone-breaks-fractures-and-heals/). We need healthy muscle tone and activation in order to do the kinds of weight-bearing activities that help us maintain bone density as we age. Changes in muscular system function can negatively affect our breathing, proprioception, strength, and endurance. Ultimately, reduced muscle function can reduce our quality of life by limiting the kinds of [activities we can do](https://3dmusclelab.com/functional-movement/) and how independent we can be in our later years. ## What can you do to slow muscle decline? The good news is that lifestyle interventions seem to have a positive effect on slowing muscle decline. We all have to get older, but we have some control over how fast we get there. Muscle mass and strength are faster and easier to lose than they are to build and maintain. Therefore, consistency of different types of exercise and movement activities is key. Both resistance exercises and aerobic exercise affect protein synthesis, and therefore affect muscle mass. However, the specific effects of each are different. A variety of exercise types seems to address the widest array of age-related changes to our muscular system. Including strength-building exercises, resistance training, aerobic exercise, and [mobility exercises](https://3dmusclelab.com/what-happens-when-we-stretch-muscles/) will go a long way toward slowing the process of age-related decline in our muscular system if no other disease or other contextual factors are present. ## Conclusion The inevitable aging process results in a decline in skeletal muscle mass, muscle strength, and muscle tone. This can have negative consequences like decreased balance and an increased likelihood of falling. However, we can slow the age-related decline of our muscle tissue by staying consistent with a variety of types of exercise, including resistance training, aerobic exercise, and mobility exercises. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Kedlian, V.R., Y. Wang, and T. Liu, et al. 2024. Human skeletal muscle aging atlas. Nature Aging 4:727–744.](https://www.nature.com/articles/s43587-024-00613-3) [McCormick, R., Vasilaki, A. Age-related changes in skeletal muscle: changes to life-style as a therapy. Biogerontology 19, 519–536 (2018).](https://link.springer.com/article/10.1007/s10522-018-9775-3) [McCuller C., R. Jessu, A.L. Callahan. Physiology, Skeletal Muscle. 2025. [Updated 2023 Jul 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537139/](https://www.ncbi.nlm.nih.gov/books/NBK537139/) [Nair, K.S. Aging muscle. 2005. American Journal of Clinical Nutrition. 81(5):953–963.](https://pubmed.ncbi.nlm.nih.gov/15883415/) [Shur, N.F., L. Creedon, S. Skirrow, P.J. Atherton, I.A. MacDonald, J. Lund, and P.L. Greenhaf. 2021. Age-related changes in muscle architecture and metabolism in humans: The likely contribution of physical inactivity to age-related functional decline. Aging Research Reviews. 68:101344. Pgs. 7.](https://pmc.ncbi.nlm.nih.gov/articles/PMC8140403/) [Tieland, M., I. Trouwborst, and B. C. Clark. 2018. Skeletal muscle performance and ageing. Journal of Cachexia, Sarcopenia, and Muscle. 9(1):3-19.](https://pubmed.ncbi.nlm.nih.gov/29151281/) --- Source: https://3dmusclelab.com/abdominal-muscles/ Author: David Keil · Updated: 2025-12-17 Muscle reference · Trunk # Your Abdominal Muscles: More Than Just A Six-Pack From superficial to deep, the four main muscles that are usually considered the abdominal group include: rectus abdominis, external oblique, internal oblique, and transverse abdominis. These four muscles are arranged in interwoven layers of muscle tissue and associated fascia. They are essential for structural support and healthy breathing. ![Abdominal Muscles](https://3dmusclelab.com/wp-content/uploads/2024/01/abdominal-muscles.jpg) When we say the word abdominals, people often think of the superficial layer of [muscles](https://3dmusclelab.com/what-is-a-muscle/) that those folks in swimsuit ads are always showing off. But the muscles that surround our abdomen are far more than that. They are essential for structural support and healthy breathing. In this article, we’ll take a closer look at which muscles make up the abdominal group, where they’re located, and what they do. ## Quick facts Origin · Insertion · Action - **Origin**: **Rectus abdominis:** crest of the pubic bone and the pubic symphysis **External oblique:** external surface of the 5th through the 12th rib **Internal oblique:** anterior iliac crest, the lateral portion of the inguinal ligament, and the thoracolumbar fascia **Transverse abdominis:** internal surface of the costal cartilage of ribs 7-12, anterior iliac crest, lateral inguinal ligament, thoracolumbar fascia, linea alba, pubic crest - **Insertion**: **Rectus abdominis:** xiphoid process and the costal cartilage of the 5th, 6th, and 7th ribs **External oblique:** linea alba, anterior iliac crest and pubic tubercle **Internal oblique:** lower three or four ribs, the linea alba, and the pubic crest - **Action**: **Rectus abdominis:** compress the abdominal contents, stabilize the trunk and spine, flex the spine, forced expiration **External oblique:** compress the abdominal contents, stabilize the trunk and spine, flex the spine (bilateral), same-side lateral flexion and opposite-side rotation (unilateral), forced expiration **Internal oblique:** compress the abdominal contents, stabilize the trunk and spine, flex the spine (bilateral), same-side lateral flexion and same-side rotation (unilateral), forced expiration **Transverse abdominis:** compress the abdominal contents, stabilize the trunk and spine, forced expiration ## What muscles make up the abdominal group? From superficial to deep, the four main muscles that are usually considered the abdominal group include: - Rectus abdominis - External oblique - Internal oblique - Transverse abdominis (There is also a small muscle called pyramidalis which is sometimes considered an abdominal muscle, but which we don’t cover in this article.) ![](https://3dmusclelab.com/wp-content/themes/3dml/assets/img/3dml-mark.png) This muscle is one of 65 covered in **3D Muscle Lab**, the 15-hour course behind these articles. [See the course →](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) ## Muscle attachments These four muscles are arranged in interwoven layers of muscle tissue and associated [fascia](https://3dmusclelab.com/what-is-muscle-fascia/). They all span broad areas and for that reason have many [points of attachment](https://3dmusclelab.com/muscle-origin-insertion-and-action/). It’s important to remember when talking about muscle attachments that humans are variable! We describe the common attachments for each of the four abdominal muscles, but there is some variability from person to person. ### Rectus abdominis Rectus abdominis is the most superficial layer, however, at its inferior attachment, it actually weaves through the transverse abdominis to end up as the deepest [layer of tissue](https://3dmusclelab.com/what-is-connective-tissue/) at that point. Rectus abdominis attaches at its superior end to the xiphoid process and on the costal cartilage of the 5th, 6th, and 7th ribs. Its fibers run vertically on either side of the fascia that divides the sections of this muscle, called the linea alba. At its inferior end, rectus abdominis attaches to the crest of the pubic bone and to the cartilaginous [joint](https://3dmusclelab.com/synovial-joint/) where the two sides of the pubis meet called the pubic symphysis. ### External oblique The next layer underneath the rectus abdominis, are the two sides of the external oblique. It attaches at the superior end on the external surface of the 5th through the 12th rib. Then, on both our right and left sides, the fibers of this muscle run at an oblique angle (hence the name) to insert into the linea alba and attach onto the anterior iliac crest and pubic tubercle. ### Internal oblique Deep to the external oblique muscles are the internal oblique muscles. Like the external obliques, we have a right and left side of these muscles. Both sides attach at the superior end onto the lower three or four ribs, the linea alba, and the pubic crest. Both sides of the internal obliques then run at an oblique angle to attach at the inferior end onto the anterior iliac crest, the lateral portion of the inguinal ligament, and the thoracolumbar fascia. ### Transverse abdominis The transverse abdominis is the deepest layer of musculature that is part of the abdominal group. The fibers of transverse abdominis run roughly horizontally as its name suggests. It wraps around the lower part of our abdomen from the thoracolumbar fascia to the linea alba. More specifically, it attaches to the internal surface of the costal cartilage of ribs 7-12, the anterior iliac crest, the lateral portion of the inguinal ligament, the thoracolumbar fascia, the linea alba, and the pubic crest. ## Muscle actions Between the four layers of abdominal muscles, we have muscle fibers wrapping around our abdomen going in every direction. This arrangement helps support the main actions of all four of the abdominals. All four muscles work to compress the abdominal contents. The [actions](https://3dmusclelab.com/muscle-agonists-antagonists-and-synergists/) of the whole abdominal group are also essential for stabilizing the trunk and spine in both static posture and [movement](https://3dmusclelab.com/what-is-the-gait-cycle/). In particular, research indicates the internal obliques, external obliques, and transverse abdominis are more active in [standing](https://3dmusclelab.com/anatomical-position/) and sitting postures, but are less active in a supine, lying-down position (Mesquita Montes et al, 2016; Snijders et al., 1995; De Troyer, 1983). Each of the individual muscles also has additional actions that they contribute to. The muscle fiber direction of each of the specific layers of abdominals defines their additional actions. Rectus abdominis has fibers that run from superior to inferior vertically. That makes it well-placed to flex the spine. The external obliques, internal obliques, and transverse abdominis each have two sets of fibers, one on each side of the abdominal aponeurosis. For that reason, they have actions that they do unilaterally (on one side) and bilaterally (both sides working together). Bilaterally, the external and internal obliques work with the rectus abdominis to flex the [spine](https://3dmusclelab.com/exploring-the-spine/). The external and internal obliques both unilaterally do lateral flexion on the same side of the body as the muscles that are [contracting](https://3dmusclelab.com/muscle-contractions/). However, because of their fiber direction, when the external obliques unilaterally contract, they rotate the body in the opposite direction. When the internal obliques unilaterally contract, they rotate the body in the same direction as the muscles that are contracting. Finally, the abdominal muscles are an important part of breathing. All four abdominal muscles contribute to forced expiration. That’s a more technical way to refer to actions like coughing. These muscles are sometimes considered “secondary respiratory muscles” because they work in addition to our main muscle of respiration, the diaphragm. They’re particularly important when we increase the stress on our breathing system, like when we’re exercising. A recent study confirmed that the external obliques and rectus abdominis are active during our exhale generally, but the activity of both of those muscles increased as the intensity of exercise increased during the study (Abraham et al., 2002). ## Are abdominal muscles part of “the core”? How are the abdominal muscles related to the idea of “the core”? There is no official definition of the term “the core.” What is true is that none of the abdominal muscles cross or act directly on the hip joint. They all attach to some part of the pelvis, so the tension in these muscles is part of the relationship between the position of the ribcage and the position of the pelvis. But, they don’t connect the legs to the torso. So while the abdominal muscles certainly contribute to stabilizing the spinal column, their primary actions affect the spine and the abdominal contents. ## Conclusion The abdominal muscles are a unique group with multiple functions. They cover a large portion of our torso. They fill in much of the space between the top of our pelvis and the bottom of our ribcage. Their location and interwoven arrangement make them an essential part of both stabilizing and moving our torso. They are also important for healthy breathing. The course ## Learn all 65 muscles the way you just learned this one. 12 modules · 79 lessons · 11 quizzes · 30-day guarantee. [See what's inside](https://3dmusclelab.com/anatomy-and-muscle-online-course-details/) [Try the free lesson](https://3dmusclelab.com/free-hamstring-lesson/) ## References [Abraham K.A., H. Feingold, D.D. Fuller, M. Jenkins, J.H. Mateika, R.F. Fregosi. 2002. Respiratory-related activation of human abdominal muscles during exercise. J Physiol. 541(Pt 2):653-63.](https://pubmed.ncbi.nlm.nih.gov/12042369/) [Mesquita Montes A., J. Baptista, C. Crasto, C.A. de Melo, R. Santos, J.P. Vilas-Boas. 2016 Abdominal muscle activity during breathing with and without inspiratory and expiratory loads in healthy subjects. J Electromyogr Kinesiol. 30:143-50.](https://pubmed.ncbi.nlm.nih.gov/27434376/) [Snijders, C.J., M.P. Bakker, A. Vleeming, R. Stoeckart, H.J. Stam. 1995. Oblique abdominal muscle activity in standing and in sitting on hard and soft seats. Clinical Biomechanics. 10(2):73-78.](https://pubmed.ncbi.nlm.nih.gov/11415534/) [De Troyer, A. 1983. Mechanical role of the abdominal muscles in relation to posture. Respir Physiol. 53(3):341-53.](https://www.sciencedirect.com/science/article/abs/pii/003456878390124X)