Sternocleidomastoid muscle (SCM)
The sternocleidomastoid muscle (SCM) is one of over 20 pairs of muscles acting on the neck. The SCM has dual innervation and multiple functions. It is a superficially palpable muscle with importance as an anatomical landmark within the neck region and as part of neuromuscular pathologies such as torticollis.
The SCM can work alone or in conjunction with the opposite side. Alone, the SCM rotates the face to the opposite side and lifts it towards the ceiling. When working in pairs, the SCMs flex the head and neck.