66 



THE BONES. 



external face is divided into two portions by a vertical crest ; the portion situated in front 

 of this crest forms part of the lachrymal channel. By its internal face, the lachrymal 

 bone limits, outwardly, the bottom of the nasal cavities, and covers tlie anterior cells of the 

 ethmoid ; by its pooterior border, within the orbit, it articulates with the os planum of 

 the ethmoid. 



11. Nasal bone. — The proper bones of the nose of Man exhibit a great analogy to 

 those of the Dog. They do not possess a nasal prolongation, and they articulate with 

 the lateral cartilage of the nose. 



12. Vomer. — The same general form and relations as in solipeds. 



13. Inferior maxillary bone. — This bone in Man is in sliape somewhat like a horse- 

 shoe. It is nearly of the same width throughout its whole extent. The symphysis is 

 vertical — a character peculiar to Alan. Below this symphysis is a triangular projection, 

 the mental eminence The genial surface of the Horse is replaced by four little tubercles 

 termed the genial processes. The alveoli of the molar teeth form a great projection on 

 the inner face of the bone. The mylo-hyoid ridge is very developed. ^ The superior 

 orifice of the dental canal is covered by a litile sharp lamina. From this orifice begins the 

 mylo-hyoiilean groove. The coronoid process is short ; the condyle is bent towards the 

 median line, and the sigmoid notch is wide and shallow. The superior border contains 

 fourteen or sixteen alveoli. 



Akticle III. — The Thokax. 



The thorax represents a conoid cage, elongated from before to betind, 

 suspended under the vertebrae of the dorsal region, and destined to contain 

 the principal organs of respiration and circulation. It is composed of bony 

 arches named ribs, thirty-six in number — eighteen on each side — and a single 

 piece, the sternum, which serves for the direct or indirect support of the 

 inferior extremities of the ribs. 



THE BONES OF THE THORAX IN PAETICULAB. 



1. Sternum of the Sorse. 



This is an osteo-cartilaginous body, elongated from before backwards, 

 flattened on each side in two-thirds of its anterior extent, and from above 

 to below in its posterior third, slightly curved on itself, and situated beneath 

 the thorax in an oblique direction from above to below, and before to behind. 

 It oifers for study, a superior face, two lateral faces, three borders, and two 

 extremities. 



Fig. 37, 



THE STERNUM. 



1. The cervical prolongation (or cariniform cartilage), 2, The xiphoid appendage (or ensiform 



cartilage; 3, 3, Cavities for the articulation of the sternal cartilages 4 4, Inferior border. 



Faces.— ^he superior face, slightly concave longitudinally, represents an 

 isoscelated, lengthened triangle, the summit of which is directed forwards; 

 it constitutes the floor of the thoracic cavity. Each lateral face comprises 

 two parts— a superior and an inferior. The first shows eight diarthrodial 



