What is "sternocleidomastoid muscle"

n. (context anatomy English) A paired muscle in the superficial layers of the anterior portion of the neck, acting to flex and rotate the head.

n. one of two thick muscles running from the sternum and clavicle to the mastoid and occipital bone; turns head obliquely to the opposite side; when acting together they flex the neck and extend the head [syn: sternocleidomastoid, sternocleido mastoideus, musculus sternocleidomastoideus]

In human anatomy, the sternocleidomastoid muscle , also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the side of the neck. It is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the accessory nerve.

It is given the name sternocleidomastoid because it originates at the manubrium of the sternum (sterno-) and the clavicle (cleido-), and has an insertion at the mastoid process of the temporal bone of the skull.