[TA] masticatory muscle of infratemporal fossa; origin, pterygoid fossa of sphenoid and tuberosity of maxilla; insertion, medial surface of mandible between angle and mylohyoid groove; action, elevates mandible closing jaw; nerve supply, nerve to medial pterygoid from mandibular division of trigeminal. SYN: musculus pterygoideus medialis [TA], internal pterygoid muscle, musculus pterygoideus internus.