148 SPECIAL ANATOMY OF THE SKELETON 



the face from the forehead. They are strong and arched, and terminate internally on each side 

 of the root of the nose in the internal angular process, which articulates with the lacrimal bone. 

 Externally they terminate in the external angular process, which articulates with the malar bone. 

 This arched ridge is sharper and more defined in its outer than in its inner half, and forms an 

 overhanging process which protects and shields the lacrimal gland. It thus protects the eye in 

 its most exposed situation and in the direction from which blows are most likely to descend. The 

 supraorbital arch varies in prominence in different individuals. It is more marked in the male 

 than in the female, and in some races of mankind than others. In the less civilized races, as the 

 forehead recedes backward, the supraorbital arch becomes more prominent, and approaches 

 more to the characters of the monkey tribe, in which the supraorbital arches are very largely devel- 

 oped, and acquire additional prominence from the oblique direction of the frontal bone. (2) The 

 internal angular process is scarcely to be felt. Its position is indicated by the angle formed 

 by the supraorbital arch with the nasal process of the maxilla and the lacrimal bone at the inner 

 side of the orbit. Between the internal angular processes of the two sides is a broad surface 

 which assists in forming the root of the nose, and immediately above this a broad, smooth, 

 somewhat triangular surface, the glabella, situated between the superciliary ridges. (3) The 

 external angular process is much more strongly marked than the internal, and is plainly to be 

 felt. It is formed by the junction or confluence of the supraorbital and temporal ridges, and, 

 articulating with the malar bone, it serves to a very considerable extent to support the bones of 

 the face. In carnivorous animals the external angular process does not articulate with the malar, 

 and therefore this lateral support to the bones of the face is not present. (4) The zygomatic 

 arch is plainly to be felt throughout its entire length, being situated almost immediately under 

 the skin. It is formed by the malar bone and the zygomatic process of the temporal bone. At 

 its anterior extremity, where it is formed by the malar bone, it is broad and forms the prominence 

 of the cheek; the posterior part is narrower, and terminates just in front and a little above the 

 tragus of the external ear. The lower border is more plainly to be felt than the upper, in conse- 

 quence of the dense temporal fascia being attached to the latter, which somewhat obscures its 

 outline. Its shape differs very much in individuals and in different races of mankind. In the 

 skulls of savages as, for instance, in the skull of the negro of the Guinea Coast the malar bones 

 project forward and not outward, and the zygoma at its posterior extremity extends farther 

 outward before it is twisted on itself to be prolonged forward. This makes the zygomatic arch 

 stand out in bold relief, and affords greater space for the Temporal muscle. In skulls which 

 have a more pyramidal shape, as in the Eskimos or Greenlanders, the malar bones do not pro- 

 ject forward and downward under the eyes, as in the preceding form, but take a direction out- 

 ward, forming with the zygoma a large, rounded sweep or segment of a circle. Thus it happens 

 that if two lines are drawn from the zygomatic arches, touching the temporal ridges, they meet 

 above the top 'of the head, instead of being parallel, or nearly so, as in the European skull, in 

 which the zygomatic arches are not nearly so prominent. This gives to the face a more or less 

 oval type. (5) Behind the ear is the rnastoid portion of the temporal bone, plainly to be felt, 

 and terminating below 7 in a nipple-shaped process. Its anterior border can be traced immediately 

 behind the concha, and its apex is on about a level with the lobule of the ear. It is rudimentary 

 in infancy, but gradually develops in childhood, and is more marked in the negro than in the 

 European. (6) The external occipital protuberance (inion) is always plainly to be felt just 

 at the level where the skin of the neck joins that of the head. At this point the skull is thick for 

 the purposes of safety, w T hile radiating from it are numerous curved arches or buttresses of bone 

 which give to this portion of the skull further security. (7) Running outward on either side from 

 the external occipital protuberance is an arched ridge of bone, which can be more or less plainly 

 perceived. This is the superior curved line of the occipital bone, and gives attachment to 

 some of the muscles which keep the head erect on the vertebral column; accordingly, we find it 

 more developed in the negro tribes, in whom the jaws are much more massive, and therefore 

 require stronger muscles to prevent their extra weight carrying the head forward. Below 7 this 

 line the surface of bone at the back of the head is obscured by the overlying muscles. Above it 

 the vault of the cranium is thinly covered with soft structures, so that the form of this part of the 

 head is almost exactly that of the upper portion of the occipital, the parietal, and the frontal 

 bones themselves; and in bald persons, even the lines of junction of the bones, especially the 

 junction of the occipital and parietal at the lambdoid suture, may be defined as a slight depression 

 caused by the thickening of the borders of the bones in this situation. (8) In the line of the 

 greatest transverse diameter of the head, on each side of the middle line, are generally to be found 

 the parietal eminences, one on each side of the middle line, though sometimes these eminences 

 are not situated at the point of the greatest transverse diameter, which is at some other prominent 

 part of the parietal region. They denote the point where ossification of the parietal bone began. 

 They are much more prominent and well marked in early life, in consequence of the sharper 

 curve of the bone at this period, so that it describes the segment of a smaller circle. Later in life, 

 as the bone grows, the curve spreads out and forms the segment of a larger circle, so that the 

 eminence becomes less distinguishable. In consequence of this sharp curve of the bone in early 

 life, the whole of the vault of the skull has a squarer shape than it has in later life, and this appear- 



