| Lateral pterygoid muscle | |
|---|---|
| The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed. (Labeled as "pterygoideus externus", visible in pink at center.) | |
| Sagittal section of the articulation of the mandible. (Labeled as "pterygoideus externus", visible in gray at bottom right.) | |
| Latin | m. pterygoideus lateralis, m. pterygoideus externus |
| Gray's | subject #109 386 |
| Origin | Great wing of sphenoid and pterygoid plate |
| Insertion | Condyle of 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 |
| MeSH | Pterygoid+Muscles |
The lateral pterygoid (or external pterygoid) is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.
Contents |
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 condyle of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule of the TMJ.
The mandibular branch of the fifth cranial nerve, the trigeminal nerve, specifically the V3 branch, innervates the lateral pterygoid muscle.
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 acts in helping lower 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.
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