Muscles of Mastication

1. Masseter;

2. Pterygoideus externus;

3. Pterygoideus internus;

4. Temporalis.

The Masseter is a thick, somewhat quadrilateral muscle, consisting of two portions, superficial and deep. It originate from the anterior two thirds of the zygomatic arch and zygomatic process of maxilla and inserts into the lateral surface of the angle and lower ramus of mandible. Its main action is to elevate the mandible, enabling forced closure of the mouth.

The Pterygoideus externus or the Lateral Pterygoid muscle originates from the infratemporal surface of sphenoid bone and the lateral surface of lateral pterygoid plate. It inserts in the pterygoid fovea below condyloid process of mandible. Its main action is to depress and protract the mandible to open the mouth as well as pulling forward the cartilage of the joint during the opening of the mouth.

The Pterygoideus internus or the Medial Pterygoid muscle originates from the lateral pterygoid plateand the tuberosity of the maxilla and pyramidal process of palatine bone. It inserts in the medial aspect of the angle of the mandible. Its main action is to elevate, protract and laterally displace the mandible to the opposite side for chewing.

The Temporalis muscle originates from the temporal fossa between inferior temporal line and infratemporal crest. It inserts in the medial and anterior aspect of the coronoid process of the mandible. Its main action is to elevate and retract the mandible.