Muscles of the neck: An overview

Superficial muscles

These are a group of 3 paired muscles in the anterior neck:

• the platysma
• sternocleidomastoid
• subclavius muscles

The platysma lies superficial to the investing layer of deep cervical fascia; the sternocleidomastoid and subclavius muscles are enclosed in this layer of fascia.

The platysma is a superficial sheath-like muscle. It originates directly from the skin overlying the regions above and below the clavicle, passing superiorly to insert on to the skin overlying the region of the lower jaw. Due to its direct attachment to the skin, the platysma is involved in facial expression, pulling the corners of the mouth inferiorly, such as in expression of sadness. It is innervated by the cervical branch of the facial nerve. The platysma is the muscle that is used to stretch the skin, making it taut and providing a smoother surface for shaving the neck region.

The sternocleidomastoid is a large, superficial muscle of the neck. It is the muscle that appears to run diagonally beneath the skin when the head is turned to the opposite side. It originates as two heads from the medial clavicle and the sternum, and passes superiorly to insert onto the mastoid process on the posterior aspect of the temporal bone. Unilateral (or 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. It is innervated by the accessory nerve (the 11th cranial nerve), and anterior rami of spinal nerves C2 and C3.

The subclavius is a small muscle located beneath the clavicle. It originates from the upper aspect of the 1st rib, and passes superiorly and laterally to insert onto the lower border of the clavicle. Its function is to pull the clavicle towards the sternum, reinforcing the sternoclavicular joint. Its innervation is the nerve to the subclavius, a branch of the upper trunk of the brachial plexus.

Why not make your studies easier with our head and neck muscle chart? These handy revision tables verified by experts will teach you everything you need to know about the attachments, innervations and functions of the musles of the neck.

Suprahyoid muscles

The suprahyoid muscles are a group of 4 paired muscles located above the hyoid bone in the neck. They all insert onto the hyoid bone and are involved in elevation of the bone during swallowing. Together, they partially form the floor of the oral cavity.

The digastric muscle consists of two parts or bellies, as suggested by its name. The anterior and posterior bellies are connected by a central tendon that is attached to the hyoid bone. The anterior belly originates from the digastric fossa on the mandible; the posterior belly originates from the mastoid notch on the temporal bone. It’s insertion is onto the hyoid bone via the central tendon.

When the hyoid bone is fixed, the digastric muscle assists in opening the mouth. When both bellies contract simultaneously, the muscle elevates the hyoid bone. The anterior belly is innervated by the mylohyoid branch of the trigeminal nerve as the posterior belly is innervated by the facial nerve. The split innervation is due to the differing embryological origins of the bellies of the muscle.

The mylohyoid muscle extends from the mylohyoid line on the inner mandible to the midline central tendon, called the midline raphe. The midline raphe continues to insert onto the hyoid bone. Mylohyoid elevates the hyoid bone, and is innervated  by the mylohyoid nerve, a branch of the mandibular nerve.

The geniohyoid muscle originates from the inferior mental spines on the inner surface of the mental symphysis. It also inserts onto the hyoid bone. It is innervated by the 1st cervical nerve and the hypoglossal nerve. 

The stylohyoid extends from the styloid process of the temporal bone to the hyoid bone. It is innervated by the facial nerve. 

Infrahyoid muscles

The infrahyoids are a group of 4 paired muscles located inferior to the hyoid bone in the anterior neck.

The sternohyoid, thyrohyoid and omohyoid muscles depress the hyoid bone. This facilitates downward movement of the larynx after swallowing. They are supplied by the ansa cervicalis (C1-C3). 

The sternohyoid muscleis the most superficial of the infrahyoids, originating from the anterior surface of the sternoclavicular joint and manubrium and inserting onto the body of the hyoid bone.

The sternothyroid muscle lies deep to the sternohyoid. It originates from the posterior surface of the manubrium and inserts onto the oblique line of the thyroid cartilage.

The thyrohyoid muscle is the continuation of the sternothyroid cartilage superiorly. It originates from the oblique line of the thyroid cartilage, and inserts onto the body and greater horn of the hyoid bone.

The omohyoid muscleconsists of two bellies: a superior and an inferior. It originates from the superior border of the scapula, and passes superomedially to a central tendon overlying the carotid sheath. It continues superiorly to insert onto the body of the hyoid bone.                                   

Scalene muscles

The scalene muscles are a group of 3 paired muscles in the anterolateral neck. They extend from the cervical vertebrae to the first two ribs. The muscles elevate the ribs. Unilateral contraction produces lateral flexion of the neck, and bilateral contraction also produces anterior flexion of the neck.

The scalenus anterior originates from the transverse processes of the C3-C6 cervical vertebrae and inserts onto the upper aspect of the 1st rib.

The scalenus nedius extends from the transverse processes of the C3-C7 to the first rib, inserting posterior to scalenus anterior.

The scalenus posterior originates from the transverse processes of the C5-C7 and inserts onto the second rib.

Superficial muscles

Splenius capitis and splenius cervicis are a pair of superficial muscles in the back of the neck. Bilateral contraction of these muscles produces extension of the neck. Unilateral contraction produces lateral flexion and rotation to the same side. They are innervated by the dorsal rami of the middle and lower cervical nerves.

The splenius capitis originates from the spinous processes of C5-T3 via the nuchal ligament. It inserts onto the mastoid process of the temporal bone.

On the other hand, the splenius cervicis extends from the spinous processes of T3-T6 to the transverse processes of C1-C3.

Suboccipital muscles

The suboccipital muscles are a compartment of 4 small paired muscles inferior to the external nuchal protuberance and the inferior nuchal line.

They are mainly postural muscles of the cervical region, but are involved in movements of the head including extension, lateral flexion, and rotation at the atlantoaxial joint. They are all innervated by the suboccipital nerve.

The rectus capitis posterior major originates from the spinous process of the axis. It inserts onto the lateral aspect of the inferior nuchal line. It produces extension and ipsilateral rotation.

The rectus capitis posterior minor originates from the tubercle on the posterior arch of the atlas and inserts onto the median aspect of the inferior nuchal line. It produces extension and ipsilateral rotation.

The obliquus capitis inferior originates from the spine of the axis and inserts onto the transverse process of the atlas. It produces rotation to the ipsilateral side.

Finally the, obliquus capitis superior extends from the transverse process of the atlas to the superior and inferior nuchal lines of the occipital bone. It produces extension and lateral flexion.

Transversospinalis muscles

The transversospinalis muscles are a group of muscles extending across all levels of the vertebral column.

These muscles are divided into subgroups depending on the region in which they are active. For example, the rotatores (spinae) muscles are divided into rotatores cervicis, thoracis and lumborum groups. The transversospinalis muscles are involved in rotation and extension of vertebral column. They are innervated throughout their course by the dorsal rami of the spinal nerves.

The semispinalis Capitis originates from the transverse processes of the upper thoracic and lower cervical vertebrae and inserts between the superior and inferior nuchal line on the occipital bone.

The semispinalis Cervicis originates from the transverse processes of the upper thoracic vertebrae and inserts onto the spinous processes of C1-C5.

The rotatores Cervicis originates from the transverse processes of the cervical vertebrae and inserts onto the laminae and transverse processes of the vertebrae 1-2 levels above.      

The interspinales in the cervical region extends from the spinous process of the cervical vertebrae to the spinous process of the adjacent vertebra.

Last but not least, the intertransversarii muscles in the cervical region extend between the transverse processes of adjacent cervical vertebrae.