What Is Temporomandibular Joint Disorder?

Temporomandibular Joint Disorder or TMJ Disorder

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 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.

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 (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, or even in areas more distant from the TMJ, such as the shoulders 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, 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 on the two sides of the head, neck, 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.

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

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/

Palmer, J. and J. Durham. 2021. Temporomandibular disorders. British Journal of Anaesthesia Education. 21(2):44-50.

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.

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.

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