The digastric muscle (also digastricus) is a small muscle located under the jaw. When the digastric muscle contracts, it acts to elevate the hyoid bone. If the hyoid is being held in place (by the infrahyoid muscles), it will tend to depress the mandible (open the mouth).

The lateral pterygoid (or external pterygoid) is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.

In human anatomy, the masseter is one of the muscles of mastication. The masseter is a thick, somewhat quadrilateral muscle, consisting of two parts, superficial and deep. The fibers of the two portions are continuous at their insertion. The masseter muscle is sometimes the target of plastic jaw reduction surgery.

The medial pterygoid (or internal pterygoid muscle), is a thick, quadrilateral muscle of mastication. The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle. It consists of two heads. The bulk of the muscle arises as a deep head from just above the medial surface of the lateral pterygoid plate. The smaller, superficial head originates from the maxillary tuberosity and the pyramidal process of the palatine bone.

The platysma is a superficial muscle that overlaps the sternocleidomastoid. It is a broad sheet arising from the fascia covering the upper parts of the pectoralis major and deltoid; its fibers cross the clavicle, and proceed obliquely upward and medially along the side of the neck.

Temporalis is a broad, fan-shaped muscle on each side of the head that fills the temporal fossa, superior to the zygomatic arch so it covers much of the temporal bone. If the entire muscle contracts, the main action is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws. If only the posterior part contracts, the muscle moves the lower jaw backward.