The lateral pterygoid is a paired primary muscle of mastication. It is a thick and short triangular-shaped muscle located in the infratemporal fossa of the skull. Overall, it stretches between the sphenoid bone and the mandible. This muscle acts particularly during speaking, singing, and clenching.

The lateral pterygoid muscle is composed of two heads - superior and inferior. The inferior head is larger than the superior, and it is also known as the pterygoid head, while the superior head is smaller and is also called the sphenoid head.

Origin: superior head - infratemporal surface of the greater wing of the sphenoid, superior one-fourth of the lateral aspect of the lateral pterygoid plate of the sphenoid bone; inferior head - inferior two-thirds of the lateral aspect of the lateral pterygoid plate, lateral aspect of the pyramidal process of the palatine bone, a small portion of the maxillary tuberosity of the maxilla.

Insertion: superior head - anteromedial border and medial aspect of the articular disc of the temporomandibular joint (TMJ), anterior part of the neck of the mandible (condylar process); inferior head - pterygoid fovea of the condylar process of the mandible, TMJ capsule.

Action: bilateral contraction - protrusion of the mandible (both muscles act together with the medial pterygoids); also, they contribute to the depression of the mandible (assisted by the mylohyoid and anterior belly of the digastric); unilateral contractions - side-to-side movement (rotation) of the mandible to the opposite side (muscle acts together with the medial pterygoid of the same side).

Innervation: lateral pterygoid nerve that is a branch of the mandibular division (CN V3) of the trigeminal nerve (CN V).

Blood supply: pterygoid arteries of the maxillary artery, ascending palatine artery of the facial artery.

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Lateral pterygoid muscle