How the Body Works : Chewing and Biting

Chewing and biting actions are largely controlled by the movement of five muscles on either side of the head. Contraction of the buccinators compresses the cheeks. these muscles, together with the tongue, are used to position food in the mouth. The internal pterygoids are responsible for the side-to-side grinding movement of the jaws, while external pterygoids open the mouth and allow the jaw to protrude, creating back and forth grinding movements. The masseter muscles, stretching from the cheekbones to the base of the lower jaw, are responsible for raising and for lowering the jaw and are particularly important in biting. Contractions of the temporalis muscles, situated at the sides of the head, clench the teeth. They work in conjunction with the masseter muscles to coordinate the biting of food.