Muscles In The Neck
By Robert Lim, PTA
The neck muscles are responsible for the functional movement of the head in the cervical spine region in all directions. The muscles of the neck are comprised of a complex number of different muscle groups. They can be subdivided into anterior (front), lateral (sides), and posterior (back) groups based on their position in the neck. Further, they can be divided into specific groups based on several factors, including depth of muscle, the muscle’s position, and the muscle’s overall function.
Anterior Neck Muscles
The first group of muscles in the neck we will talk about will be the neck’s anterior muscles. The major muscles in the anterior section of the neck are the platysma, sternocleidomastoid, and the subclavius muscle. Further, the platysma muscle is a superficial muscle in the neck. It originates directly from the skin overlying above and below the clavicle bone, passing superiorly to insert on to the skin overlying the region of the lower jaw.
The platysma is involved in facial expression, pulling the corners of the mouth down, such as making the expression sad. The platysma is the muscle used to stretch the skin to allow grooming such as shaving and grooming with less difficulty. Further, the sternocleidomastoid is a large, superficial muscle of the neck. This muscle runs diagonally beneath the skin when the head is turned to the opposite side.
Unilateral (one-sided) contraction of the sternocleidomastoid muscle produces lateral rotation of the head. Bilateral (both sides) contraction of the muscle produces flexion of the neck. Further, the subclavius is a small muscle located beneath the clavicle. It originates from the 1st rib and passes superiorly and laterally to insert onto the clavicle’s lower border. Further, the subclavius’s major function is to pull the clavicle towards the sternum, reinforcing the sternoclavicular joint.
Lateral Neck Muscles
The second group of muscles in the neck is the lateral neck muscles. These muscles are responsible for flexion and lateral flexion of the neck in the cervical region. These muscles play an important role in the stabilization of the cervical vertebral column. Further, there are four major lateral neck muscles: longus capitis, longus cervices, rectus capitis anterior, and rectus capitis lateralis.
The longus capitis muscle originates from the tubercles of the transverse processes of C3-C6. It inserts onto the inferior surface of the occipital bone.
The longus cervicis originates from the C5-T3 vertebrae. It inserts onto C2-C4, the anterior tubercles of C5-C6, and the tubercle of the anterior arch of the atlas.
Let’s look at the rectus capitis anterior and rectus capitis lateralis. Rectus capitis anterior originates from the atlas and inserts to the foramen magnum on the occipital bone base. Rectus capitis lateralis extends from the atlas’ transverse process to the internal aspect of the occipital bone.
Posterior Neck Muscles
The third group of muscles in the neck is the posterior muscles. These muscles are responsible for the extension of the neck. Unilateral contraction produces lateral flexion and rotation to the same side. Further, the muscles that are responsible for this are Splenius capitis and splenius cervicis muscles. Other posterior neck muscles include muscles from the Suboccipital muscles.
The sub occipital muscles are made up of four small, paired muscles. These muscles are Rectus capitis posterior major, Rectus capitis posterior minor, Obliquus capitis inferior, and the Obliquus capitis superior muscle. Further, another subgroup is the transversospinalis muscles. These muscles are split into smaller groups depending on location in which they are active.
As a group, the transversospinalis muscles extend, laterally flexes, and contralaterally rotates the neck at each of the spinal joints; it extends and laterally flexes the head at the atlanto-occipital joint. The transversopsinalis muscles’ muscles are Semispinalis capitis, Semispinalis cervicis, Rotatores cervicis, Interspinales cervicis, and the Intertransversarii.
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Written by: Robert Lim, PTA