Anatomy, Head and Neck, Lateral Pterygoid Muscle

The lateral pterygoid muscle is a craniomandibular muscle that plays a crucial role in the craniofacial system. It is the key muscle of the inferior temporal region. The Lateral pterygoid muscle is active during mastication and during mandibular movements such as protrusion (forward movement of the mandible), abduction (depression of the mandible), mediotrusion (movement of the mandibular condyle towards the midline), and particularly during speaking, singing, and clenching. Among all the muscles of mastication, it is the only muscle with fibers arranged horizontally. Functionally, the muscle is analogous to the temporalis muscle. The fan-shaped temporalis muscle exhibits a continuous range of movements anteroposteriorly, while the lateral pterygoid muscle exhibits a continuous range of functional movements mediolaterally as well as superoinferiorly. The lateral pterygoid muscle has two heads or bellies. The inferior belly is three times larger than the superior belly.