Longus capitis muscle

Origin and insertion

Longus capitis is a long flat muscle of the anterior neck. It runs up the length of the cervical spine, adjacent to the vertebral bodies. 

Longus capitis muscle originates from its inferior aspect, as four small muscle straps that run from the anterior tubercles of transverse processes of the third, fourth, fifth and sixth cervical vertebrae. From these straps, the muscle fibers run superomedially, converging into a single broad muscle belly. The muscle has one insertion on the basilar part of occipital bone, anterior to the insertion of the rectus capitis anterior muscle and lateral to the pharyngeal tubercle.

Relations 

Longus capitis is the most superficial muscle of the prevertebral muscle group. Its superior aspect lies in front of the rectus capitis anterior muscle, while the inferior part slightly covers the longus cervicis muscle. The retropharyngeal lymph nodes are located on the lateral border of the longus capitis muscle. The anterior vertebral vein and the adjacent ascending cervical artery, pass through the interval between the attachments of scalenus anterior muscle and longus capitis muscle. 

Together with the other prevertebral muscles, the cervical spine is covered in a tubular sheath made of the prevertebral layer of cervical fascia that extends from the base of the skull to the body of the third thoracic vertebra.

Innervation

The longus capitis muscle is innervated by anterior rami of the spinal nerves C1-C3 and occasionally C4, that are the branches of the cervical plexus. 

Blood supply

Longus capitis is supplied from the muscular branches of the ascending cervical artery and the inferior thyroid artery. Venous blood is drained by the vertebral vein which arises in the suboccipital triangle from numerous muscle branches from the internal vertebral venous plexuses.

Function

Working synergistically with the other prevertebral muscles and sternocleidomastoid muscle, the longus capitis muscle acts as a weak flexor of the head and cervical spine. The prevertebral muscles are the most important antagonists of the extensors of the head (e.g. trapezius muscle and levator scapulae muscle), thus have an important role in stabilization of the cervical spine. When the head is in an extended position, longus capitis’ flexion action brings the head back into a neutral position. 

To expand your knowledge, test yourself with our learning materials about the main muscles of the head and neck.