Either of two bones that frame the mouth : a movable lower jaw (mandible) and a fixed upper jaw (maxilla).
These hold the teeth (see tooth ) and are used for biting and chewing and in speech. Vertical portions at the back of the lower jaw form hinge joints at the temples. The front of its arch thickens to form the chin. The upper jaw is attached to bones at the bridge of the nose, in the eye sockets and roof of the mouth, and the cheekbones. It contains the large maxillary sinus .