1 The remaining part of my work relates to the bones; and to make this more easily understood, I will begin by pointing out their positions and shapes.
First then comes the skull, concave internally, convex externally, on both aspects smooth, where it covers the cerebral membrane as well as where it is covered by the skin bearing hair; and it is in one layer from the back of the head to the temples, in two layers from the forehead to the vertex. Its bones are hard externally, but the inner parts which connect them together are softer, and between these run large blood-vessels which probably supply their nutrition. It is rare for the skull to be solid without sutures; in hot countries, however, this is more easily found; and that kind of head is the firmest and safest from headaches. As for the rest, the fewer the sutures, the better for the heads; and there is no certainty as to the number, or even as to the position of the sutures. Generally, however, there are two above the ears separating the temples from the upper part of the head: a third stretches to the ears across the vertex and separates the occiput from the top of the head. A fourth runs likewise from the vertex over the middle of the head