Muscle · Jaw

Lateral pterygoid

Musculus pterygoideus lateralis

A short, deep, two-headed muscle that pulls the jaw forward rather than closing it — the odd one out among the chewing muscles. It is the muscle that opens the jaw, in the sense that it slides the jaw joint forward while the muscles under the chin drop the chin down. What makes it clinically important is where its upper head attaches: directly into the capsule and cartilage disc of the jaw joint itself, which is why it is implicated whenever a jaw clicks, catches or deviates to one side on opening.