sternocleidomastoid (muscle)


ster·no·clei·do·mas·toid (mus·cle) (SCM),

[TA] superficial muscle of the anterolateral neck; origin, by two heads from anterior surface of manubrium of the sternum and sternal end of clavicle; insertion, mastoid process and lateral half of superior nuchal line; action, turns head obliquely to opposite side; when acting together, flex the neck and extend the head; nerve supply, motor by accessory, sensory by cervical plexus. Synonym(s): musculus sternocleidomastoideus [TA], sternomastoid muscle