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Neck Muscles: The Superficial And Mid-layers

Neck Muscles

Our neck has many critical functions and it's the muscles that surround our cervical spine that support its 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. 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.

Superficial and mid-layer muscles in the neck

  • Trapezius
  • Sternocleidomastoid
  • Levator scapulae
  • Anterior scalenes
  • Middle scalenes
  • Posterior scalenes
  • Splenius capitis
  • Splenius cervicis

Muscle attachments

It’s important to point out that there is variation from person to person in the points of attachment (origin and insertion) 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 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

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 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. 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. Our neck is an important part of our body for both initiating movement and maintaining posture. 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.

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 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.

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