Final answer:
False. The sternocleidomastoid muscle laterally flexes the neck to the same side, but it rotates the head to the opposite side when acting unilaterally. When acting bilaterally, these muscles flex the head forward. Therefore, the statement presented is false.
Step-by-step explanation:
Function of the Sternocleidomastoid Muscle
The statement that the sternocleidomastoid muscle will laterally flex the cervical spine to the ipsilateral side and rotate the cervical spine to the ipsilateral side is false. When the sternocleidomastoid muscles act unilaterally (individually), they are responsible for rotating the head to the opposite side of the contracting muscle. If the right sternocleidomastoid contracts, the head rotates to the left, and vice versa. On the other hand, when the sternocleidomastoid muscles contract bilaterally (both sides together), they contribute to flexing the head forward. These muscles are innovated by the accessory nerve, which also innervates the trapezius muscles, having a role in movements of the neck and shoulders.