The inferior head of the lateral pterygoid is unique in being active during mouth opening rather than closing. It pulls the mandibular condyle anteriorly during jaw opening and is the primary protrusor of the mandible.
| Origin | Lateral surface of the lateral pterygoid plate of the sphenoid |
|---|---|
| Insertion | Neck of the mandibular condyle and articular disc |
| Nerve Supply | Lateral pterygoid nerve — branch of mandibular nerve (V3) |
| Blood Supply | Pterygoid branches of maxillary artery |
| Actions | Opens the mouth — the inferior head contracts during jaw opening (opposite to other jaw muscles); Protrudes the mandible; Produces lateral jaw excursion to the opposite side |
|---|
The inferior head's attachment to the condylar neck is the site of traction that produces the condyle's forward slide in jaw opening. In condylar fracture surgery, the inferior head attachment contributes to the medial displacement of the condylar segment. Lateral pterygoid botulinum injection targets the inferior head for TMJ hypermobility and chronic dislocation.
Not externally palpable — accessed via intra-oral approach.
Inferior head lateral pterygoid pull on the condylar neck displacing the condylar fragment medially in subcondylar fractures, complicating closed reduction.
