Which muscle raises the mandible?

The masseter is the primary muscle responsible for elevating the mandible (the lower jaw), allowing for actions such as chewing and biting. It is located in the jaw area and connects the zygomatic arch to the ramus of the mandible, facilitating powerful movements essential for mastication. This muscle is particularly well-developed in individuals who engage in heavy chewing, as it needs to generate significant force to raise the mandible against resistance.

In contrast, the other muscles listed do not have roles related to the elevation of the mandible. The pectoralis major is primarily involved in movements of the shoulder joint, such as flexion, adduction, and internal rotation of the arm. The trapezius is mostly responsible for movements of the shoulders and head, including shrugging the shoulders and tilting the head backward. The deltoid muscle is primarily involved in shoulder abduction and stabilization of the arm.

Thus, the masseter is correctly identified as the muscle that raises the mandible.