The lateral pterygoid is the only jaw muscle with two heads with opposing functions. The inferior head protrudes and opens the jaw; the superior head holds the TMJ disc against the condyle during closing. Superior head dysfunction from chronic bruxism allows anterior disc displacement, producing the clicking TMJ of disc displacement with reduction.
| Origin | Superior head: infratemporal surface of the greater wing of the sphenoid. Inferior head: lateral surface of the lateral pterygoid plate |
|---|---|
| Insertion | Superior head: TMJ disc and capsule. Inferior head: condylar neck (pterygoid fovea) |
| Nerve Supply | Lateral pterygoid nerve (mandibular nerve V3) |
| Blood Supply | Pterygoid branches of the maxillary artery |
| Actions | Inferior head: jaw protrusion and mouth opening (with digastric and suprahyoids); Superior head: controls TMJ disc position during jaw closing; Unilateral: lateral jaw excursion to the opposite side |
|---|
Lateral pterygoid spasm or hypertrophy contributes to TMJ anterior disc displacement — the superior head fails to control disc position during jaw closing, allowing the disc to slip anteriorly. This produces the classic click as the condyle slips back under the disc during opening. Lateral pterygoid botulinum toxin injection is performed via intraoral or transcutaneous approach for TMJ internal derangement.
The lateral pterygoid is not palpable from the surface — assessed via intraoral palpation at the posterior maxillary tuberosity region during jaw movements.
Superior lateral pterygoid head dysfunction allowing anterior TMJ disc displacement producing clicking managed with splint therapy and lateral pterygoid injection.
