Muscle · Jaw

Medial pterygoid

Musculus pterygoideus medialis

A thick, quadrilateral muscle hidden on the inner side of the jaw, mirroring the masseter on the outside — together the two form a muscular sling that cradles the angle of the jaw and lifts it. It closes the jaw, helps push it forward, and, working with its opposite number, swings the jaw side to side for grinding. Because it is deep and hard to reach, it is often the muscle still holding tension after the masseter has been released, and it is a common source of jaw ache that feels 'inside' or 'behind' the jaw rather than on the cheek.