The socket of the eye is called the orbit. Its shape is a rounded trapezoid, angled downward to the lateral side. Its top, bottom, and medial borders are at the same level, but the lateral border drops back into the skull about half the distance of the height of the orbit.
The broad bone of the forehead is called the frontal bone, whose two forward-most corners are called the frontal eminences. Between each of the frontal eminences and the orbits is a raised form called the brow ridge. Between the brow ridges is the glabella (
gluh-BELL-uh), the so-called keystone of the brow. There is an important depression between the glabella and the nasal bone which usually is in shadow and is crucial for separating the top plane of the nose from the plane of the forehead. On the lateral side, the brow ridge points downward to form the upper corner of the orbit.
The lower corner and bottom edge of the orbit is formed by the zygomatic (
zigh-go-MAT-ic) bone. The bottom of the zygomatic bone is even with the pit of the nose. The zygomatic bone reaches around the side of the skull with an elongated form called the zygomatic arch. (The zygomatic arches and the brow ridges form a pair of inverted eyeglasses on the face.)
The sides of the skull are squared off in relation to the dome shape on top. The recessed region at the temple is called the temporal fossa. At the forward edge of the temporal fossa, the bone turns sharply outward to meet the brow ridge and zygomatic bone. This rise is called the temporal ridge. Just above the level of the bottom of the orbit, it turns sharply from a more-vertical to a more-horizontal angle. When the head is conceived as a box, the temporal ridges are regarded as its front edges.
The upper jaw is a half-cylinder of bone called the maxilla. The lower jaw, called the mandible, has two important features that affect the appearance of the face: its angle, and the mental protuberance, a horizontal ridge that gives the chin its form. Its lateral corners are called the mental tubercles.