46 VETERINAEY STATE BOARD 



The superior extremity is large and rounded and shows : a large 

 cavity, the maxillary sinus; the infra-orbital canal ; and the palatine 

 canal. 



The inferior extremity presents a cavity which forms the alveolus 

 of the tusk, and unites with a similar space in the premaxillary bone. 



Describe the inferior maxilla. 



The inferior maxillary is a very large bone, situated behind the 

 upper jaw, and is composed of two symmetrical branches, joined at 

 their lower extremities to form the intermaxillary space. It consists 

 of two extremities, an inferior and superior, two faces, external and 

 internal, and two borders, a superior and inferior. 



The inferior extremity shows the body of the bone which is 

 formed by the union of the two lateral halves. The inferior face 

 is smooth and convex, and shows the inferior opening of the maxillo- 

 dental canal — the mental foramen; on a level with this foramen, 

 the bone markedly contracts to form the neck. The superior face 

 is smooth and concave ; it supports the free extremity of the tongue. 

 The circumference is convex anteriorly and contains six sockets for 

 the incisors, and behind these — ^in the male only — on either side is 

 an additional socket for the tusks. The space between the lateral 

 incisors and tusks is called the bars, or inferior interdental space. 



The superior extremity shows the condyloid process which 

 articulates with the glenoid cavity of the temporal bone ; the neck, 

 a constriction below the condyle; the coronoid process, in front of 

 the condyle and separated from it by the sigmoid notch, is flattened 

 on its sides and receives the terminal insertion of the temporalis 

 muscle. 



The external face is smooth and rounded in its inferior two- 

 thirds and roughened above for the insertion of the masseter 

 muscle. The internal face presents in its upper one-third the 

 superior orifice of the inferior maxillodental canal which runs down 

 tmder the molar teeth, between the two plates of the bone, to the 

 mental foramen; in its inferior two-thirds the internal face is 

 smooth. Near the alveolar border and running parallel therewith 

 is the myloid ridge. At the junction of the two sides is a roughened 

 excavation — the genial surface. 



The superior, or alveolar border, shows a straight or inferior 

 portion which is hollowed by six alveoli to receive the inferior molar 

 teeth, and a curved or superior portion for muscular insertion. 

 The inferior border shows a sharp, straight portion and a more 

 rounded portion above. The union of these two portions forms the 

 angle of the jaw. 



