noun
: either of two muscles extending from the sphenoid bone to the lower jaw:
a. : an external muscle that arises from the greater wing of the sphenoid and from the outer surface of the lateral pterygoid lamina, is inserted into the condyle of the mandible and the interarticular disk, and acts as an antagonist of the masseter, temporal, and internal pterygoid muscles
b. : an internal muscle that arises from the inner surface of the lateral pterygoid lamina and the palatine and maxillary bones, is inserted into the angle and ramus of the mandible, cooperates with the masseter and temporal in elevating the lower jaw, and controls certain lateral and rotary movements of the jaw