Skull

Skull. The skull consists of twenty-two separate bones, eight of these forming the cranium, and the remainder entering into the constitution of the face. Below and at the back part of the skull is situated the occipital bone. In front of this, and entering into the formation of the basal part of the skull are the sphenoid and the ethmoid bones, the lateral aspects of the cranial vault are formed by the two parietal bones, and in front of these are the two frontal bones. The temporal bone of either side lies below the parietal and in front of the occipital bone, its anterior margin articulating with a portion of the sphenoid bone. The fourteen bones of the face consist of the pairs of nasal, superior maxillary, lachrymal, palatine, inferior turbinated, and malar bones, with the single vomer and the inferior maxillary bone. The bones of the cranial vault are closely united with one another, the intervening sutures being markedly serrated. The suture which separates the frontal from the parietal bones is termed the coronal suture, while that which intervenes between the two parietal bones is called the sagittal suture. Various holes (foramina) perforate the base of the skull, and allow of the exit of the cranial nerves and the blood-vessels. The largest of these is the foramen magnum in the occipital bone, and through it passes the medulla oblongata which connects the brain with the spinal cord. The spaces which remain unossified at birth, in the middle line of the skull at the anterior and posterior extremities of the sagittal suture, are called the fontnanelles; the anterior fontanelle is not completely closed by bony growth until the first or second year after birth. The posterior fontanelle is closed within a few months of birth. There are also two lateral fontanelles situated at the anterior and lower angles of the parietal bones; these, however, become completely ossified very shortly after birth. The skulls of different racial types present distinct peculiarities, which have been made to serve as a basis of classification. The brachycephalic skull is a skull whose breadth is great in proportion to its length, and the dolichocepbalic skull is one in which the breadth is less considerable in proportion to the length; the mesocephalic skull occupies an intermediate position between these two extremes.