sternocleidomastoid

Superficial muscle of the anterolateral neck. Origin: (by 2 heads) 1) anterior surface of the manubrium of the sternum 2) sternal end of the clavicle Insertion: 1) mastoid process 2) lateral 1/2 of superior nuchal line Action: 1) turns head obliquely to the opposite side 2) when acting bilaterally together, flexes neck & extends head Innervation: 1) motor: accessory nerve (CN XI) 2) sensory: cervical plexus

References

Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999