Structure - The lateral pterygoid muscle has an upper head and a lower head. - The upper head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone. - The lower head originates on the lateral surface of the lateral pterygoid plate. - The upper head inserts onto the articular disc and fibrous capsule of the temporomandibular joint. - The lower head inserts onto the pterygoid fovea at the neck of the condyloid process of the mandible.

Blood supply - The lateral pterygoid muscle is supplied by pterygoid branches of the maxillary artery.

Nerve supply - The lateral pterygoid muscle is supplied by the lateral pterygoid nerve, a branch of the mandibular nerve (CN V). - The mandibular nerve is itself a branch of the trigeminal nerve (CN V).

Function - The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible. - A concerted effort of the lateral pterygoid muscles helps in lowering the mandible and opening the jaw. - Unilateral action of a lateral pterygoid muscle causes contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids. - When they work independently, they can move the mandible side to side. - Unlike the other three muscles of mastication, the lateral pterygoid alone can assist in depressing the mandible (opening the jaw).

Clinical significance - The lateral pterygoid muscle may be involved in temporomandibular joint dysfunction.