Logan Steele
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues. There are about 30 neck muscles, which are skeletal muscles attached to bones by tendons. These muscles support the head and neck and help with various movements, such as chewing, swallowing, and breathing. The neck muscles can be categorized into three main groups: anterior, lateral, and posterior, based on their position in the neck. The cervical spine, consisting of seven cervical vertebrae (C1-C7), provides flexibility and a range of motions to the neck. The cervical nerves (C1-C8) play a crucial role in stimulating muscle movement and providing sensation to the neck and other parts of the body.
| Characteristics | Values |
|---|---|
| Number of neck muscles | 30 |
| Types of neck muscles | Anterior, lateral, and posterior |
| Anterior neck muscles | Platysma, sternocleidomastoid, suprahyoid, infrahyoid, and scalene muscles |
| Posterior neck muscles | Superficial, suboccipital, and transversospinalis |
| Function of neck muscles | Support and stabilise the head, neck, and upper part of the spine; enable head movement in different directions; assist with chewing, swallowing, and breathing |
| Innervation | Cervical nerves C2-C5 and cranial nerve XI (spinal accessory nerve) |
| Primary motions of the OA joint | Flexion and extension |
| Primary motion of the upper portion of the lower cervical unit (C2-C4) | Rotation |
| Primary motion of the lower portion of the lower cervical unit | Side-bending |
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What You'll Learn
Lateral neck muscles
The neck muscles are skeletal muscles, meaning they are attached to bones by tendons. They are voluntary muscles, so we can control how they move and work. There are about 30 neck muscles, which can be divided into three main groups based on their position in the neck: anterior (front), lateral (side), and posterior (back).
The lateral neck muscles, also called the lateral vertebral muscles, are a group of muscles that pass obliquely along the lateral sides of the neck. These muscles control head movements from the base of the skull, helping us twist our heads from side to side and tilt and twist our cervical spines. They include the anterior, middle, and posterior scalene muscles, which extend between the transverse processes of the cervical vertebrae and the upper two ribs. The anterior scalene muscle is the most anterior of the scalene muscles, arising from the anterior tubercles of the transverse processes of vertebrae C3-C6 and inserting onto the scalene tubercle and the superior border of the first rib. The middle and posterior scalene muscles also originate from the cervical spine, but attach to the first and second ribs, respectively.
The sternocleidomastoid is another important muscle in the lateral neck region. It is a large, two-headed muscle of the neck, with its clavicular head originating from the medial third of the clavicle and its sternal head arising from the manubrium of the sternum. These heads come together and ascend diagonally to insert onto the mastoid process of the temporal bone. Unilateral contraction of the sternocleidomastoid produces lateral flexion of the neck on the same side and lateral rotation of the head to the opposite side. Bilateral contraction of these muscles produces flexion of the neck, drawing the head towards the chest.
Overall, the lateral neck muscles play a crucial role in enabling various head movements and maintaining the stability of the head and neck region.
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Posterior neck muscles
The neck muscles are skeletal muscles, meaning they are attached to bones by tendons. They support and stabilise the head, neck and the upper part of the spine, and help move the head in different directions. The neck muscles are innervated by various cervical nerves and their branches, and cranial nerves.
The posterior neck muscles are located on the posterior aspect of the neck and connect the skull to the vertebral column and pectoral girdle. They can be subdivided into three groups: superficial, deep, and deepest. The superficial layer is composed of the trapezius and the two splenius muscles (capitis and cervicis). The trapezius functions to produce lateral flexion and contralateral rotation of the head if contracting unilaterally, or extension of the head if contracting bilaterally. It also stabilises and moves the scapula in different directions, depending on which fibres contract. The splenius muscles cause lateral flexion and ipsilateral rotation of the head and neck when contracting unilaterally, or extension of the head and neck when contracting bilaterally.
The deep layer is composed of the transversospinales muscles of the cervical region: semispinalis capitis, semispinalis cervicis and multifidus cervicis. The primary function of this group is lateral flexion and contralateral rotation of the head and neck when contracting unilaterally, and extension of the head and neck when contracting bilaterally.
The deepest layer consists of the suboccipital muscles (rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, and obliquus capitis inferior), interspinales cervicis, and intertransversarii colli. The primary function of the suboccipital muscles is to produce movements of the head (extension, lateral flexion, and rotation) as well as maintaining posture. The suboccipital muscles are a group of four muscles located in the posterior region of the neck, inferior to the occipital bone. They serve as postural support of the head and neck and allow neck extension and rotation movements.
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Superficial muscles
The neck muscles are skeletal muscles, meaning they are attached to bones by tendons. They are voluntary muscles, so we have control over their movement. There are about 30 neck muscles, which can be categorised as anterior (front), lateral (side) and posterior (back) muscles.
The anterior neck muscles are further divided into four subgroups: superficial, suprahyoid, infrahyoid, and scalene muscles. The superficial muscles are the most superficial in the anterior neck, and include the platysma and sternocleidomastoid. The platysma is a sheet-like muscle that lies within the subcutaneous tissue of the anterior neck. It originates from the skin and fascia overlying the clavicle and passes superiorly along the neck. It is innervated by the cervical branch of the facial nerve and vascularised by the submental branch of the facial artery and suprascapular branch of the thyrocervical trunk. The platysma functions mainly as a muscle of facial expression, for example, it contributes to producing an expression of sadness by pulling the corners of the mouth downwards.
The sternocleidomastoid is a large, two-headed muscle of the neck. Its clavicular head originates from the medial third of the clavicle, while its sternal head arises from the manubrium of the sternum. The heads come together and ascend diagonally to insert onto the mastoid process of the temporal bone. The sternocleidomastoid muscle is innervated by the accessory nerve and anterior rami of spinal nerves C2 and C3. Its function depends on whether it acts alone or together with its counterpart on the other side. Unilateral contraction produces lateral flexion of the neck on the same side and lateral rotation of the head to the opposite side.
The superficial muscles in the back of the neck help to extend and rotate the head.
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Suboccipital muscles
The suboccipital muscles are a group of four muscles located underneath the occipital bone at the base of the skull. They are known as postural muscles that help maintain the posture of the head and neck, and allow neck extension and rotation movements. The four muscles are:
- Rectus capitis posterior major
- Rectus capitis posterior minor
- Obliquus capitis superior
- Obliquus capitis inferior
The suboccipital muscles are innervated by the suboccipital nerve, which is formed by the dorsal ramus of C1. The vertebral artery, which supplies the suboccipital muscles, ascends superiorly alongside the cervical spinal vertebrae. At the level of C6, it traverses the remaining vertebrae until C2, where it exits. The suboccipital venous plexus is the main venous structure surrounding and draining the suboccipital muscles.
The suboccipital triangle is an anatomic landmark formed by three of the four suboccipital muscles. It contains the vertebral artery, suboccipital venous plexus, and suboccipital nerve. The triangle is particularly important to surgeons operating in the posterior cervical region to avoid life-threatening bleeding.
The suboccipital muscles are clinically significant due to their proximity to the vertebral artery and their role in surgical access to the posterior cranial fossa. Various cranial pathologies can be accessed through a suboccipital surgical approach, which requires knowledge of the posterior cervical region. Additionally, these muscles have been implicated in the development of cervicogenic headaches due to their connections with the dura mater.
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Transversospinalis muscles
The transversospinalis muscles are a group of deep back muscles that help move the head forward and backward, as well as tilt it from side to side. They also help stabilise the spine and move the cervical, thoracic, and lumbar regions of the spine. These muscles are small and have a poor mechanical advantage for contributing to motion. They include the three semispinalis muscles, the multifidus muscle, and the rotatores muscles.
The semispinalis is the most superficial of the transversospinalis muscle group. It originates from the transverse process and crosses between four and six vertebrae to attach to the spinous process. The semispinalis muscles have the longest fascicles of the transversospinalis group, spanning six segments. The muscles in this group are the semispinalis capitis, semispinalis cervicis, and semispinalis thoracis.
The multifidus muscle lies deep to the semispinalis and spans the entire length of the vertebral column, being most developed in the lumbar region. The multifidus extends from the cervical to the sacral levels, covering the laminae of the underlying vertebrae from the cervical to upper lumbar levels, then expanding to encompass the sacrum at the lumbosacral levels.
The rotatores muscles are the deepest muscles in the transversospinalis group and have the shortest fascicles, spanning one to two segments. The rotatores consist of two parts: the long rotatores (longus) and the short rotatores (brevis). The long rotatores pass from the transverse process medially to the spinous process, crossing two vertebrae, while the rotatores brevis pass from the transverse process and insert at the base of the spinous process of the vertebrae above the origin. The rotatores muscles are identified as rotators in many texts, but this action has not been validated, and they are more likely stabilisers of the spinal column.
The transversospinalis muscles share the same nerve supply from the dorsal rami of the spinal nerves. The nerves that supply these muscles include the vertebral, deep cervical, occipital, transverse cervical, posterior intercostal, subcostal, lumbar, and lateral sacral arteries. The bilateral contraction of the transversospinalis muscles extends the spine, while unilateral contraction rotates it.
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Frequently asked questions
Neck muscles are skeletal muscles that are attached to bones by tendons. They support your head and help you move it in different directions. There are about 30 neck muscles, which can be categorised into anterior (front), lateral (side) and posterior (back) muscles.
Anterior neck muscles cover the front of the neck. They are divided into three subgroups: superficial, suprahyoid and infrahyoid muscles. The platysma is an example of a superficial muscle, which lies within the subcutaneous tissue of the anterior neck.
Lateral neck muscles control head movements from the base of the skull. They help you twist your head from side to side and tilt your cervical spine.
Posterior neck muscles are responsible for the extension of the neck. They include superficial, suboccipital and transversospinalis muscles. The suboccipital muscles are just below the occipital bone at the base of the skull and help extend your head in different directions.
