The sternocleidomastoid is the major muscle that laterally flexes and rotates what?
knee
tongue
eye
head
Muscles That Move the Head The head, attached to the top of the vertebral column, is balanced, moved, and rotated by the neck muscles (Table 11.5). When these muscles act unilaterally, the head rotates. When they contract bilaterally, the head flexes or extends. The major muscle that laterally flexes and rotates the head is the sternocleidomastoid. In addition, both muscles working together are the flexors of the head. Place your fingers on both sides of the neck and turn your head to the left and to the right. You will feel the movement originate there. This muscle divides the neck into anterior and posterior triangles when viewed from the side (Figure 11.14).