muscles acting on the head and neck

sternocleidomastoid

unilateral action tilts head slightly upwards and toward the opposite side, as in looking over one’s contralateral shoulder

scalenes (anterior, middle, posterior)

unilateral contraction causes ipsilateral flexion or contralateral rotation depending on action of other muscles

trapezius

• extends neck as in looking up

• laterally flexes neck

splenius capitis & splenius cervicis

• acting unilaterally, produce ipsilateral flexion and slight rotation of head

• extend head when acting bilaterally

semispinalis capitis & semispinalis cervicis

extend and contralaterally rotate head