The lateral pterygoid muscle has two distinct heads with different functions: the inferior head protrudes and depresses the mandibular condyle during jaw opening, while the superior head controls the position of the TMJ articular disc. The superior head's disc attachment means it modulates disc-condyle coordination throughout the jaw movement cycle, and its dysfunction contributes to TMJ internal derangement with disc displacement.
| Origin | Infratemporal surface of the greater wing of the sphenoid bone and infratemporal crest |
|---|---|
| Insertion | Articular disc and capsule of the temporomandibular joint (unlike the inferior head which inserts on the condylar neck) |
| Nerve Supply | Nerve to lateral pterygoid (branch of anterior division of mandibular nerve, V3) |
| Blood Supply | Maxillary artery branches; masseteric artery |
| Actions | Protrudes the articular disc anteriorly during mouth opening; acts eccentrically during mouth closing to control disc position; contracts with the inferior head during ipsilateral jaw deviation and contralateral excursion |
|---|
Superior head dysfunction is central to TMJ internal derangement pathophysiology. Abnormal superior head contraction during closing displaces the disc anteriorly, producing the classic click (disc recapture) or lock (non-reducing disc displacement). MRI demonstrates disc-condyle relationships in open and closed mouth positions. Botulinum toxin injection into the superior head is used for TMJ pain and myofascial pain. Arthroscopic disc repositioning surgery addresses the disc-condyle relationship.
Hyperactivity of the lateral pterygoid superior head anteriorly displaces the TMJ articular disc relative to the condyle, producing a click on mouth opening when the condyle slides under the displaced disc; chronic displacement produces closed lock with limited opening and pain requiring arthroscopic disc repositioning or condyloplasty.
