Milady Esthetics State Board Practice Test 2025 - Free Esthetics Exam Practice Questions and Study Guide

The muscle that plays a key role in head movement is the sternocleidomastoideus. This muscle is primarily responsible for the flexion and rotation of the head. When one side of the sternocleidomastoideus contracts, it allows the head to rotate to the opposite side, while contraction of both sides results in the forward bending of the neck.

The other muscles listed, while they do have important functions, do not primarily facilitate head movement. The masseter is mainly involved in the chewing process, as it is one of the primary muscles responsible for elevating the jaw. The frontalis muscle is part of the epicranius and primarily functions in the movement of the forehead, such as raising the eyebrows and wrinkling the forehead. The temporalis muscle, similar to the masseter, is also involved in the process of mastication (chewing), aiding in the elevation and retraction of the mandible. Therefore, the sternocleidomastoideus stands out as the primary muscle involved in head movement.