Dominic Stone
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues that support the skull and allow for movement. There are about 30 neck muscles that help stabilise and move the head, neck, and upper spine. These muscles are skeletal muscles, meaning they are attached to bones by tendons. They are voluntary muscles, so we control how they move and work. The muscles that move the head work together to facilitate a wide range of head movements, including rotation, flexion, extension, and lateral bending.
| Characteristics | Values |
|---|---|
| Number of neck muscles | 30 |
| Types of neck muscles | Anterior, lateral (prevertebral), and posterior |
| Examples of anterior neck muscles | Platysma, sternocleidomastoid, subclavius, mylohyoid, geniohyoid |
| Examples of lateral neck muscles | Anterior, middle, and posterior scalenes |
| Examples of posterior neck muscles | Superficial, suboccipital, and transversospinalis |
| Examples of superficial muscles | Trapezius, splenius capitis, splenius cervicis |
| Examples of deep layer muscles | Cervical transversospinalis, semispinalis capitis, semispinalis cervicis, multifidus cervicis |
| Functions of neck muscles | Support and stabilize the head, neck, and upper spine; enable movement of the head in different directions; assist with chewing, swallowing, and breathing |
| 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 |
| Types of cervical movements | Cervical flexion, cervical extension, cervical rotation, cervical side-bending |
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What You'll Learn
- The SCM, suprahyoid and infrahyoid muscles are major head flexors
- Lateral neck muscles help with lateral flexion
- Anterior vertebral muscles, including rectus capitis, facilitate head flexion
- Posterior neck muscles, including splenius capitis, help extend and rotate the head
- Deep cervical transversospinalis muscles, like the semispinalis, help with head rotation and extension
The SCM, suprahyoid and infrahyoid muscles are major head flexors
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues that connect the head to the torso. The neck muscles support the head and enable it to move in various directions. They also assist with essential functions such as chewing, swallowing, and breathing.
The sternocleidomastoid (SCM) muscle is a major head flexor. It originates at the sternum and clavicle and attaches to the mastoid process of the temporal bone. When the SCM contracts bilaterally, it helps to bend the head forward. Conversely, unilateral contraction of the SCM results in lateral flexion on the same side or head rotation to the opposite side.
The suprahyoid and infrahyoid muscles are also significant head flexors. These muscles are grouped based on their position relative to the hyoid bone, with the suprahyoid muscles located above and the infrahyoid muscles below. The suprahyoid muscles consist of four muscles: digastric, stylohyoid, mylohyoid, and geniohyoid. They contribute to swallowing and mastication, depressing the mandible when the infrahyoid muscles contract. The infrahyoid muscles, on the other hand, include omohyoid, sternohyoid, sternothyroid, and thyrohyoid. They work together with the suprahyoid muscles to control the positioning of the hyoid bone, which is crucial for speech, swallowing, and the movement of the larynx.
In summary, the SCM, suprahyoid, and infrahyoid muscles play a crucial role in head flexion and related functions. Their contraction and relaxation facilitate various movements and stabilize the head, neck, and upper spine, enabling us to perform essential tasks such as chewing, swallowing, and speaking.
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Lateral neck muscles help with lateral flexion
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues. It supports the skull while allowing for a wide range of movements. The neck muscles help with various functions, including chewing, swallowing, breathing, and moving the head.
The neck muscles can be categorized into anterior, lateral (prevertebral), and posterior groups. The lateral neck muscles play a crucial role in controlling head movements and enabling twisting and tilting of the cervical spine. These muscles help with lateral flexion, which is the movement of bending the neck sideways.
Lateral flexion is a type of motion commonly associated with the neck and spine. It involves bending the neck towards one shoulder or bending the torso sideways. The lateral neck muscles facilitate this movement, allowing for a smooth and controlled sideways bend.
The scalene muscles, a type of lateral neck muscle, are particularly important for lateral flexion. They stabilize the cervical spine and enable the head to twist and tilt smoothly. Additionally, the intertransversarii muscles assist in lateral flexion of the spine and provide stabilization.
By contracting and relaxing in a coordinated manner, the lateral neck muscles enable the head and neck to bend laterally with stability and control. This movement is essential for various daily activities, such as scanning surroundings, maintaining balance, and interacting with the environment.
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Anterior vertebral muscles, including rectus capitis, facilitate head flexion
The neck is a complex structure of bones, muscles, nerves, blood vessels, lymphatics, and other connective tissues. It is the most flexible part of the spine, allowing for a large range of motion. The neck muscles support the head and help with various movements, including flexion, extension, rotation, and side-bending. They also assist with chewing, swallowing, and breathing.
The anterior vertebral muscles, including the rectus capitis, are crucial for head flexion. The rectus capitis anterior, in particular, is a short muscle located anterior to the vertebral column. It stretches between the atlas (C1) and the base of the skull. Upon contraction, this muscle aids in flexing the head at the atlanto-occipital joint. The atlanto-occipital joint, formed by the articulation of C1 with the occipital condyles of the skull, plays a vital role in head movements.
The rectus capitis anterior is one of the prevertebral and anterior neck muscles. It originates from the anterior surface of the lateral mass and transverse process of the atlas and inserts on the inferior surface of the basilar part of the occipital bone. The muscle is innervated by branches arising from the loop between the anterior rami of the first and second cervical spinal nerves (C1-C2).
Other anterior vertebral muscles also contribute to head flexion. These include the longus capitis and longus colli muscles, which are part of the prevertebral muscles and play a role in maintaining the stability and movement of the cervical spine. Additionally, the scalene muscles, comprising the scalenus anterior, scalenus medius, and scalenus posterior, are involved in head flexion. They facilitate breathing by moving the first two ribs and assist in stabilising the cervical spine.
In summary, the anterior vertebral muscles, notably the rectus capitis anterior, longus capitis, longus colli, and scalene muscles, facilitate head flexion. These muscles contract to enable bending the head forward towards the chest, which is known as cervical flexion. This movement is essential for various daily activities and maintaining proper head and neck posture.
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Posterior neck muscles, including splenius capitis, help extend and rotate the head
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues. It supports the skull and allows for a wide range of movements. Neck muscles can be divided into three main categories: anterior (front), lateral (side/prevertebral), and posterior (back).
Posterior neck muscles include superficial, suboccipital, and transversospinalis muscles. Superficial muscles are strap-like muscles in the back of the neck that help with head extension and rotation. These include the splenius capitis and splenius cervicis, which form the superficial layer of intrinsic back muscles. The splenius capitis is a thick, flat muscle at the posterior aspect of the neck, extending to the cervical vertebrae. It assists in supporting the head in an erect position. When acting unilaterally, it contributes to the lateral flexion and rotation of the head to the same side.
The suboccipital muscles are located just below the occipital bone at the base of the skull. They help extend the head in various directions and include the rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, and obliquus capitis inferior. These muscles also contribute to head rotation at the atlantoaxial joint.
The transversospinalis muscles enable forward and backward head movements, as well as side-to-side tilting. They also assist in spine stabilization and movement in the cervical, thoracic, and lumbar regions.
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Deep cervical transversospinalis muscles, like the semispinalis, help with head rotation and extension
The neck is a complex structure of bones, muscles, nerves, blood vessels, lymphatics, and connective tissues. The cervical spine, which is the bony part of the neck, supports the skull while allowing for movement. The neck muscles support the head and enable various movements, including head rotation and extension.
Deep cervical transversospinalis muscles, such as the semispinalis, are part of a group of muscles that aid in head rotation and extension. The semispinalis is the most superficial muscle in the transversospinalis group, which also includes the multifidus and rotatores muscles. These deep muscles extend from the sacrum to the base of the skull, providing stability to the vertebral column and contributing to proprioception and balance.
The semispinalis has three parts: the semispinalis capitis, semispinalis cervicis, and semispinalis thoracis. The semispinalis capitis is the largest muscle in the posterior neck, and it lies deep to the upper trapezius. It is involved in head extension and unilateral contraction, pulling the head posteriorly and rotating the chin towards the contracting muscle.
The semispinalis cervicis acts as a cervical extender, providing posterior support to the cervical lordosis and preventing a forward head position. It is also considered one of the deep cervical extensors, along with the multifidus muscle. These muscles work in synergy with the deep neck flexors to maintain proper neck posture.
The deep cervical transversospinalis muscles, including the semispinalis, play a crucial role in enabling head rotation and extension. They provide stability, facilitate movements of the vertebral column, and contribute to maintaining posture and balance. By understanding the functions of these muscles, we can appreciate their importance in supporting and facilitating the complex movements of the head and neck.
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Frequently asked questions
The muscles that flex the head include the sternocleidomastoid (SCM), the suprahyoid, and the infrahyoid muscles.
The SCM muscle is a major head flexor. When contracted bilaterally, it bends the head forward, whereas unilateral contraction causes lateral flexion or head rotation to the opposite side.
The splenius capitis, a posterior neck muscle, helps with extending and rotating the head. The scalene muscles help with lateral flexion and rotating the head to the side. The longus capitis acts as a weak flexor of the head when acting bilaterally.
The neck muscles support the head and help with a variety of movements, including chewing, swallowing, and breathing. They also assist in balance and stabilizing the bones in the neck.
