222 THE SKELETON. 



bone and the floor of the nasal fossa. It extends along the entire length of the 

 outer wall of the nose, is broader in front than behind, and presents anteriorly the 

 lower orifice of the canal for the nasal duct. 



The anterior nares present a heart-shaped or pyriform opening whose long 

 axis is vertical and narrow extremity upward. This opening in the recent state 

 is much contracted by the cartilages of the nose. It is bounded above by the 

 inferior border of the nasal bone ; laterally by the thin, sharp margin which 

 separates the facial from the nasal surface of the superior maxillary bone ; and 

 below by the same border, where it slopes inward to join its fellow of the opposite 

 side at the anterior nasal spine. 



The posterior nares are the two posterior oval openings of the nasal fossae, by 

 which they communicate with the upper part of the pharynx. They are situated 

 immediately in front of the basilar process, and are bounded above by the under 

 surface of the body of the sphenoid ; below by the posterior border of the horizontal 

 plate of the palate bone ; externally, by the internal surface of the internal pterygoid 

 plate ; and internally, in the middle line, they are separated from each other by 

 the guttural border of the vomer. 



Surface Form. The various bony prominences or landmarks which are to be easily felt and 

 recognized in the head and face, and which afford the means of mapping out the important 

 structures comprised in this region, are as follows : 



1. Supraorbital arch. 8. Parietal eminences. 



2. Internal angular process. 9. Temporal ridge. 



3. External angular process. 10. Frontal eminences. 



4. Zygomatic arch. 11. Superciliary ridges. 



5. Mastoid process. 12. Nasal bones. 



6. External occipital protuberance. 13. Lower margin of orbit. 



7. Superior curved line of occipital bone. 14. Lower jaw. 



1. The supraorbital arches are to be felt throughout their entire extent, covered by the eye- 

 brows. They form the upper boundary of the circumference or base of the orbit, and separate 

 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 lachrymal 

 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 lachrymal gland. It thus pro- 

 tects the eye in its most exposed situation and in the direction from which blows are most likely 

 to descend. Tho 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 whioh the supraorbital arches are 

 very largely developed, 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 suprao ital arch with the nasal process of the superior maxillary 

 bone and the lachrymal bone at the inner side of the orbit. Between the internal angular pro- 

 cesses 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 supra- 

 orbital and temporal ridges, and, articulating with the malar bone, it serves to a very consider- 

 able extent to support the bones of the face. In carnivorous animals the external angular pro- 

 cess 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 termi- 

 nates 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 consequence of the dense temporal fascia being attached to 

 the upper border, which somewhat obscures its outline. Its shape differs very much in individ- 

 uals and in different races of mankind. In the most degraded type of skull 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 

 Esquimaux or Greenlander, the malar bones do not project forward and downward under the 

 eyes, as in the preceding form, but take a direction outward, forming with the zygoma a large, 

 rounded sweep or segment of a circle. Thus it happens that if two lines are drawn from the 



