THE HEAD AND NECK CONTINUED
All of these movements are performed to position the head, which itself should be seen at two units: the face and the braincase. The face of the skull is a bony shield that hangs down from the rounded braincase. It is perforated by several holes that provide receptacles for the sense organs, the connection between the outside world and the brain. The eyes of the human and of most primates are on the front of the face rather than on the side as they are in most mammals. The two eyes, spaced a short distance apart, see things from two different perspectives. The combined information from these two points of view is simultaneously processed by the brain, allowing for the judging of distances. The sense organs need to be protected. The eyes are set in to the skull with prominent ridges of bone above and below them. The muscle fibers of the eyelid that are arranged around the eye are in concentric circular configuration. These muscles are tethered to the skull near the nose by a small tendon that you can feel as a small lump on the inner corner of the eye. The muscles of the lips are in a thicker, but similar circuit of muscles that when contracted as a whole, cause the lips to pucker. These muscles can also be contracted in part. Covering the opening on the skull for the organs of the sense of smell is a “tent” made of three sections of cartilage. The human nose is unusual in how it juts out from the face. Some paleo-anthropologists speculate that the prominent nose arose as a means of warming up air as it was inhaled, preventing the brain from getting too cold.
The major bony structures of the face are attachments for the most powerful muscle of the head, the muscles for chewing and biting. The delicate edge of the temple, which you can feel on the side of the head by the eye, and continues as a long graceful arch on the side of the skull, is the origin of the temporal muscle. The thin, fan shaped temporal muscle points down towards the lower jaw, into which it is inserted. This insertion is hidden from sight and touch because it occurs under the arc of bone that extends from beneath the eye to the ear. This is the zygomatic arch, or cheekbone. It is the origin of the most significant facial muscle - the masseter. The masseter is connected to the bottom edge of the zygomatic arch and descends diagonally to be inserted near the corner of the lower jaw. Once you know the front edge of the masseter is there you can discern it in even the most full cheeked subject. For the drafts-person the distance between the eye and the ear can sometimes seem like the greatest distance in the body - an empty zone with little contour. An understanding of the zygomatic arch and the masseter provides landmarks for the artist's eye in traveling this distance.
In our evolutionary development, intelligence combined with social existence made articulate speech a possible advantage. But in apes even with the reduction in size of the lower jaw, a bony shelf that reinforced the u-shape of this structure still made clear speech difficult. The solution to this was a misplacement of this buttress of bone into a knob of bone into the front of the jaw, the chin. This was a very late arrival in our skeletal structure and we must imagine our ancestors as folks with few words.
