Sternocleidomastoid

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Description

Sternocleidomastoid (SCM)is a paired superficial muscle in the anterior portion of the neck. Carotid sheath structures lie deep to it 

Origin

SCM origins from 2 heads as follows: Sternal head: anterior surface of the manubrium Clavicular head: medial 1/3rd of the clavicle

Insertion

Mastoid process and lateral 1/2 of the superior nuchal line

Nerve Supply

Spinal accessory nerve (XI), with sensory supply from C2 & C3 (for proprioception)

Blood Supply

Sternocleidomastoid branch of the Occipital artery

Action

Draws the mastoid process down toward the same side which causes the chin to turn up toward the opposite side; acting together, the muscles of the two sides flex the neck

Function

Rotation of the head to the opposite side or obliquely rotate the head. It also flexes the neck. When acting together it flexes the neck and extends the head. When acting alone it rotates to the opposite side (contralaterally) and slightly (laterally) flexes to the same side. It also acts as an accessory muscle of inspiration.

Resources

• http://www.spineuniverse.com/anatomy
• http://anatomy.uams.edu/anatomyhtml/

Recent Related Research (from Pubmed)

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References

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