Name

# Sternocleidomastoid

Pronunciation

(ster-no-kli-do-MAS-toid)

Origin/Proximal Attachment

Manubrium of the sternum & medial portion of clavicle

Insertion/Distal Attachment

Mastoid Process

Action/Relevance

Bilaterally: cervical flexion Unilaterally: lateral flexion to same side, rotation to opposite side

Innervation

Spinal Accessory nerve (CN 11, C2-3)

Notes

The sternocleidomastoid muscles are muscles in the neck that act to flex and rotate the head.

It is given the name sternocleidomastoid because it attaches to the sternum (sterno-), the clavicle (cleido-), and the mastoid process of the temporal bone of the skull.

Its motor innervation is the 11th cranial nerve (the spinal accessory or accessory nerve). Its sensory innervation is the cervical plexus.

Its blood supply comes from the occipital artery and the superior thyroid artery.

It is also called the sternomastoid muscle.