Origin
Manubrium of sternum & medial 1/4 of clavicle’s superior surface
Insertion
Mastoid process & anterior portion of superior nuchal line
Actions
- Unilateral contraction: ipsilateral flexion and contralateral rotation
- Bilateral contraction: Head/neck extension, head/neck flexion, & assists in inspiration by elevating clavicle and manubrium of sternum
Innervation
- Accessory nerve (CN XI)
- Branches of cervical plexus (C2-C3)
Blood Supply
- Occipital artery
- Superior thyroid artery
- Suprascapular arteries
Would you like to learn more about the sternocleidomastoid muscle? Then check out the sternocleidomastoid muscle article and video by clicking the link below: Sternocleidomastoid Muscle Anatomy
