Mastering the Muscles of the Neck

Study Notes

The muscles of the neck are responsible for the movement of the head in all directions.
The muscles are divided into three groups: anterior, lateral, and posterior.
The anterior neck muscles are further divided into three subgroups: suprahyoid, infrahyoid, and pretracheal muscles.
The suprahyoid muscles include the digastric, mylohyoid, geniohyoid, and stylohyoid muscles.
The digastric muscle has dual innervation and its function depends on its point of action.
The mylohyoid muscle elevates the hyoid bone and the floor of the mouth and depresses the mandible.
The geniohyoid muscle elevates the hyoid bone and moves the larynx and pharynx anterosuperiorly.
The stylohyoid muscle elevates the hyoid bone and retracts the tongue.
The infrahyoid muscles include the sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles.
The function of the infrahyoid muscles is to depress the hyoid bone and larynx to reopen the airways after swallowing.
The sternothyroid muscle is innervated by the ansa cervicalis and supplied by the lingual and superior thyroid arteries.
The thyrohyoid muscle is innervated by C1 via the hypoglossal nerve and supplied by the infrahyoid and superior laryngeal branches of the superior thyroid artery and lingual branch of the external carotid artery.
The anterior vertebral muscles are a group of muscles located anterior to the cervical vertebral column and are surrounded by the prevertebral fascia.
The rectus capitis anterior muscle arises from the lateral mass of atlas and inserts on the basilar part of the occipital bone, and is innervated by C1 and C2.
The rectus capitis lateralis muscle arises from the transverse process of the atlas and inserts onto the jugular process of the occipital bone, and is innervated by C1 and C2.
The longus capitis muscle arises from the anterior tubercles of the transverse processes of vertebrae C3-C6 and inserts onto the basilar part of the occipital bone, and is innervated by C1-C3.
The longus colli muscle spans the cervical and upper thoracic spine and is divided into three parts, and is innervated by C2-C6.
The functions of the infrahyoid muscles are to depress the hyoid bone and larynx, and the anterior vertebral muscles function to flex the head to varying degrees.
The rectus capitis anterior muscle flexes the head at the atlanto-occipital joint and stabilizes the joint.
The rectus capitis lateralis muscle flexes the head laterally at the atlanto-occipital joint and helps stabilize the joint during movement.