 | ||
Origin Great wing of sphenoid and pterygoid plate Insertion Condyloid process of the mandible Artery Pterygoid branches of maxillary artery Nerve Lateral pterygoid nerve from the mandibular nerve Actions depresses mandible, protrude mandible, side to side movement of mandible Latin Musculus pterygoideus lateralis,
musculus pterygoideus externus | ||
The lateral pterygoid or external pterygoid is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.
Contents
Origin and insertion
The upper/superior head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate.
Inferior head inserts onto the neck of condyloid process of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule of the temporomandibular joint.
Innervation
The mandibular branch of the fifth cranial nerve, the trigeminal nerve, specifically the lateral pterygoid nerve, innervates the lateral pterygoid muscle.
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 open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids.
Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid and geniohyoid muscles.