The lateral pterygoid muscle is a thick triangular muscle of the lateral aspect of face. Lying in the infratemporal fossa, it is one of the four muscles of mastication. The lateral pterygoid consists of an upper and a lower portion, or head. The upper head originates from the inferior surface and infratemporal crest of the greater wing of the sphenoid bone. Then it extends backwards to be inserted into the medial surface of the articular capsule of the mandibular joint. The lower portion, on the other hand, arises from the pterygoid process lateral plate of the sphenoid and runs obliquely downwards and backwards to be inserted into the pterygoid pit of mandible.
Action/Function
The lateral pterygoid muscle works along with the medial pterygoid and the masseter muscle to perform the function of mastication (chewing). This action is done by displacing the mandible to the contralateral side. The bilateral contraction of this muscle makes the mandible protrude forwards.
Innervation
The lateral pterygoid muscle is innervated by the lateral pterygoid nerve, which is a branch of the trigeminal cranial nerve (CN V).
Blood Supply
This triangular muscle receives oxygenated blood from the pterygoid artery, which is a branch of the maxillary artery.
Below, schematic drawing of the lateral and medial pterygoid muscle. The masseter muscle and a portion of mandible have been removed in order to see them.
