Contraction of the Right Sternocleidomastoid Muscle

Question

Contraction of the right sternocleidomastoid muscle
A) acts antagonistically to the pectoralis major.
B) acts synergistically with the trapezius.
C) hyperextends the head.
D) rotates the head down and to the left.

Accepted Answer

Contraction of the right sternocleidomastoid muscle rotates the head down and to the left. The other options are incorrect because the sternocleidomastoid muscle does not act antagonistically to the pectoralis major, it may work synergistically with the trapezius but it depends on the action being performed, and it does not hyperextend the head.