The Lateral Pterygoid muscle is a muscle of the jaw. It originates on the greater wing of the sphenoid bone and the lateral pterygoid plate. It has its insertion on the condyloid process of the mandible. Functionally it it assists in opening the jaw by pulling the head of the mandibular condyle out of the mandibular fossa. Trigger points in this muscle refer pain into the temporal mandibular joint and maxillary sinus. Trigger points in this muscle are often the cause of pain felt from TMJ dysfunction.