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The neck is made up of around 30 muscles that support and stabilise the head, neck, and upper spine, as well as enabling a range of movements. These muscles are part of a complex musculoskeletal system that connects the base of the skull to the torso. The neck muscles can be divided into anterior, lateral, and posterior groups, with further subcategories based on depth, location, and function. The cervical spine, which supports the neck, is composed of seven vertebrae, with the first two, C1 and C2, known as atypical vertebrae due to their unique bony structures designed to support and move the skull. While several muscles are involved in rotating the neck, the sternocleidomastoid muscle is key, as unilateral contraction produces lateral flexion of the neck and lateral rotation of the head to the opposite side.
| Characteristics | Values |
|---|---|
| Number of neck muscles | 30 |
| Muscle groups | Anterior, lateral (prevertebral), and posterior |
| Superficial muscles | Platysma, sternocleidomastoid |
| Suprahyoids | Digastric, mylohyoid, geniohyoid, stylohyoid |
| Infrahyoids | Sternohyoid, sternothyroid, thyrohyoid, omohyoid |
| Lateral neck muscles | Anterior, middle, and posterior scalene muscles |
| Function of sternocleidomastoid | Ipsilateral flexion and contralateral rotation of the neck |
| Function of longus colli | Ipsilateral flexion and contralateral rotation of the neck |
| Function of trapezius | Lateral flexion and contralateral rotation of the head |
| Function of cervical transversospinalis | Lateral flexion and rotation of the head to the opposite side |
| Function of suboccipital muscles | Rotation of the head and extension of the neck |
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What You'll Learn
- Sternocleidomastoid muscles enable neck rotation to the opposite side
- Trapezius muscles enable head rotation to the opposite side
- Suboccipital muscles enable head rotation
- Longus colli muscles enable neck rotation to the opposite side
- Cervical transversospinalis muscles enable head rotation to the opposite side
Sternocleidomastoid muscles enable neck rotation to the opposite side
The neck is a complex musculoskeletal system that connects the base of the skull to the torso. It consists of about 30 muscles, which support and stabilise the head, neck, and upper spine, while also enabling a range of movements. The neck muscles can be sub-categorised into anterior, lateral, and posterior groups.
The sternocleidomastoid muscle is a two-headed neck muscle that is both easily visible and palpable. It is a key landmark as it divides the neck into anterior and posterior triangles. The muscle gets its name from its attachments to the manubrium of the sternum, the clavicle, and the mastoid process of the temporal bone.
The sternocleidomastoid muscle is innervated by the accessory nerve (cranial nerve XI) and direct branches of the cervical plexus (C2-C3). It has multiple functions, including neck flexion at the inferior cervical vertebrae, elevation of the clavicle and sternal manubrium at the sternoclavicular joint, and ipsilateral flexion and contralateral rotation of the neck at the cervical spine.
Unilateral contraction of the sternocleidomastoid muscle flexes the cervical vertebral column to the same side and rotates the head to the opposite side. This is because the muscle acts as an accessory muscle of respiration, with its contraction signalling the release of acetylcholine (ACH) from vesicles, which then causes an increase in resting potential, initiating an action potential that travels along the muscle fibre.
Thus, the sternocleidomastoid muscles enable neck rotation to the opposite side through their anatomical structure, nerve signalling, and muscle contraction.
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Trapezius muscles enable head rotation to the opposite side
The neck is composed of about 30 muscles that support and stabilise the head, neck, and upper spine. These muscles help with a range of movements, including turning the head to the left or right, and assist with chewing, swallowing, and breathing.
The trapezius muscles are two large muscles found in the upper back. They are paired muscles that form a diamond or trapezoid shape when viewed together. Each trapezius muscle has three sections that run from the base of the neck down to the middle of the back. These muscles are part of the musculoskeletal system, which consists of soft tissues and bones that connect the base of the skull to the torso.
The trapezius muscles enable head rotation to the opposite side. They are involved in the movements of the head and neck, including turning the head to either side, and maintaining and adjusting posture. When the trapezius muscle acts unilaterally, the descending fibres produce an ipsilateral lateral flexion of the head and neck by acting on the atlanto-occipital joint and upper cervical vertebrae, respectively. This unilateral contraction results in contralateral rotation of the head at the atlantoaxial joint, allowing the head to turn to the opposite side.
The trapezius muscles also work with other muscles to control movements of the shoulder and upper limb. They are active during the throwing action, along with the deltoid muscle and the rotator cuff muscles. The trapezius muscles push on the shoulder blade (scapula) to help move the shoulder when lifting the arm or throwing something.
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Suboccipital muscles enable head rotation
The neck is a complex musculoskeletal system that connects the base of the skull to the torso. The neck muscles support the head and enable a range of movements, including rotation. They also assist with chewing, swallowing, and breathing. There are about 30 neck muscles, which can be divided into anterior, lateral, and posterior groups based on their position in the neck.
The suboccipital muscles are a group of four small muscles found in the suboccipital region, deep to the semispinalis muscles. These muscles include the rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, and obliquus capitis inferior. The suboccipital muscles act to rotate the head and extend the neck.
The rectus capitis posterior major and rectus capitis posterior minor attach the inferior nuchal line of the occiput to the C2 and C1 vertebrae, respectively. The obliquus capitis superior also extends from the occiput to C1, while the obliquus capitis inferior originates from C2 and attaches to C1. These muscles are all innervated by the suboccipital nerve.
The suboccipital muscles work together to enable head rotation by providing the necessary support and movement at the atlanto-occipital joint, which connects the skull to the neck. The C1 vertebra, also known as the atlas, has a unique structure that allows for rotation and other primary motions. The suboccipital muscles attach to the atlas and nearby vertebrae, facilitating the rotation of the head on the neck.
In summary, the suboccipital muscles enable head rotation by providing the necessary support and movement at the atlanto-occipital joint. These muscles attach to the vertebrae in the upper neck, especially the atlas (C1), and their contraction allows for the rotation of the head. The suboccipital muscles are an important part of the musculoskeletal system of the neck, enabling a wide range of motions and supporting the head.
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Longus colli muscles enable neck rotation to the opposite side
The neck is a complex musculoskeletal system that connects the base of the skull to the torso. It is composed of around 30 muscles, which support and stabilise the head, neck, and the upper part of the spine. These muscles also help us move our head in different directions and assist with chewing, swallowing, and breathing.
The longus colli muscle, or 'long muscle of the neck', is a paired muscle located on the anterior aspect of the vertebral column. It is also referred to as an anterior prevertebral muscle, along with the longus capitis, rectus capitis anterior, and scalenus anterior muscles. The longus colli runs the entire length of the neck, from the atlas (first cervical vertebra) to T3 (third thoracic vertebra).
The longus colli muscle is responsible for forward and lateral flexion of the neck, as well as rotation of the neck. The left and right longus colli muscles each consist of three parts: vertical, inferior oblique, and superior oblique. The superior oblique portion of the longus colli muscle originates from the anterior tubercles of the transverse processes of C3 to C5 vertebrae. It then courses superiorly to insert onto the anterior tubercle of the atlas via a narrow tendon.
The inferior oblique part of the longus colli muscle is the smallest section. It arises from the anterior surfaces of the bodies of the first three thoracic vertebrae (T1-T3) and ascends superolaterally, terminating onto the anterior tubercles of the transverse processes of the fifth and sixth cervical vertebrae (C5-C6). The inferior oblique part of the longus colli muscle is responsible for rotating the neck to the opposite side. This unilateral contraction of the inferior oblique part results in weak lateral flexion and contralateral rotation of the neck.
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Cervical transversospinalis muscles enable head rotation to the opposite side
The neck is a complex structure of bones, muscles, nerves, blood vessels, lymphatics, and other connective tissues. There are about 30 neck muscles, which support and stabilise the head, neck, and upper spine. They also enable a range of movements, including chewing, swallowing, and breathing.
The cervical spine is the bony part of the neck, composed of seven vertebrae. Cervical vertebrae C1 and C2 are "atypical" vertebrae with unique bony structures designed to support and move the skull. The cervical spine can undergo flexion, extension, rotation, and side-bending, with each cervical joint having a primary motion.
The lateral neck muscles control head movements from the base of the skull, enabling the head to twist from side to side. These muscles include the cervical transversospinalis, which help move the head forward and backward, as well as tilt it from side to side.
During unilateral contraction, the cervical transversospinalis muscles enable the head to rotate to the opposite side. They also help stabilise the spine and move the cervical, thoracic, and lumbar regions of the spine. This group of muscles comprises the semispinalis, multifidus, and rotatores muscles.
The semispinalis capitis, for example, arises from the articular processes of vertebrae C4-C7 and the transverse processes of vertebrae T1-T6. It then courses upward to insert between the superior and inferior nuchal lines of the occipital bone.
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Frequently asked questions
The splenius capitis and splenius cervicis.
The function of the sternocleidomastoid muscle depends on whether it acts alone or with its counterpart. Unilateral contraction produces lateral flexion of the neck on the same side and lateral rotation of the head to the opposite side. Bilateral contraction produces flexion of the neck, drawing the head towards the chest.
The main function of the longus colli is to flex the neck. The inferior part of the muscle can produce weak ipsilateral flexion and contralateral rotation of the neck.
