- sternocleidomastoid, sternocleidomastoid muscle, sternocleido mastoideus, musculus sternocleidomastoideus - 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
--1 is a kind of skeletal muscle, striated muscle
--1 is a part of neck, cervix