The term Head is applied to the living man; the Cranium, from which this branch of science takes its name, is the skeleton of the head. The cranium is composed of two parts, which may be virtually separated, in the lateral projection, by a straight line passing through the external orbital apophysis and extending to the auricular foramen, thus separating the facial from the cerebral portion of the cranium. Hence the cranium is the skeleton of the head in its entirety, and is divisible into the cerebral cranium and the facial cranium.
The Cranium.—The cranium is a complex union of a number of flat, curved bones united together by means of certain very complicated arborescent sutures, and forming a hollow osseous cavity of rounded form. I will briefly indicate the bones which form its external contour. On the anterior part is the frontal bone, terminated by the suture which unites it to the two parietal bones: the coronal suture; while the two parietal bones are joined together by the median or sagittal suture, which forms a sort of T with the other suture.
On the posterior side is the occipital bone, which is also joined to the two parietal bones, by means of the occipital or lambdoidal suture. Below the two parietal bones, in a lateral direction, are the two temporal bones; and between the temporal and parietal bones are situated the great wings of the sphenoid. The main body of the sphenoid is at the base of the cranium. Besides these there is another, internal bone, the ethmoid.
The Face.—The skeleton of the face is composed of fourteen bones; some of these are external and lend themselves to measurement; others which are internal and hidden contribute to the completion of the delicate scaffolding of this most important portion of the skeleton. The principal bones of the face are: the two zygomatic bones (articulating with the temporal, frontal and maxillary bones); the two nasal bones (articulating with the frontal and with the ascending branch of the maxillary, and uniting above to form the bridge of the nose; this is a bone of great importance in anthropology, because it determines the naso-frontal angle and the formation of the nose); the two upper maxillary bones, or upper jaw (articulating together in front to form the subnasal region; laterally with the zygomatic bones; above with the nasal bones; internally with each other, to form the palate, and posteriorly with the palatine bones); the mandible or lower jaw (a single bone, and the only movable bone in the cranium), articulating with the temporal bones by means of a condyle, and the separate parts of which are distinguished as the body of the mandible and the ascendant branches, which are united to the cranium.
Fig. 39.—Note the line of division between the cerebral and facial cranium; in addition to this the sutures are shown which divide the frontal, parietal, occipital and temporal bones. PD. Coronal Suture; DL. Sagittal Suture; AL. Lambdoidal Suture.
The bones of lesser importance, which are interior and hidden are: the two lacrymal bones (situated at the inner angle of the orbitary cavity), the vomer or osseous septum of the nose; the two bones in the nose which lie on each side of the vomer and are known as the turbinated bones (concha nasalis); and the two palate bones (which form the backward continuation of the palatine vault constituted by the maxillary bones).
Human Cranium and Animal Cranium.—The dividing line between the cerebral and facial cranium is of great importance in anthropology, because the relative proportions between these two parts of the cranium form a human characteristic, contrasting widely with the animal characteristics; and they offer a simple criterion for determining the higher or lower type of the human cranium. (Compare in this connection Fig. 40, skulls of the higher mammals and of man.)
