52 



TRE BONES. 



The second, thinner, concave, and rugged, serves for muscular insertion. 

 The posterior border is also divided into straight and curved portions, ihe 

 latter is convex, thick, rugged, and margined on each side by an uneven 

 lip • the first is regularly rectilinear, so that all its points rest at the same 

 time on a horizontal plane; it is thick and rounded m the young animal, 

 but becomes sharp with age ; an oblique and transverse fissure— the maxillary 

 —separates it from the curved part. The union of these two portions forms 

 the angle of the jaw. . 



Extremities. The superior extremity has two eminences : a condyle, 



and a long non-articular process named the coronoid process. The condyle is 

 elongated°transversely, and convex in its two diameters ; it responds, through 

 the medium of a fibro-oartilaginous disc, to the articular surface of the zygo- 

 matic process. The coronoid process is situated in front of the condyle, from 

 which it is separated by a division called the sigmoid or corono-oondyloid notch ; 

 it is flattened on both sides, and curved backwards and slightly inwards. 



Fig. 24. 



ISPBEIOE MAXILLA. 



1, Mental foramen ; 1', Superior orifice of the maxillo-dental canal ; 2, Surface ot 

 implantation for the masseter muscle ; 3, Myloid ridge j 4, Coronoid process ; 

 5, Condyle. 



From the union of the branches of the maxillary bone at their inferior 

 extremity results a single piece, flattened before and behind, and widened 

 like a spatula, which has been designated the body of the bone. This merits 

 a special description. 



Its form allows us to divide it into an anterior or buccal face, a posterior 

 or labial face, and a circumference. The anterior face is smooth and concave, 

 is lined by the buccal mucous membrane, and supports the free extremity 

 of the tongue. The posterior face is convex, more extensive than the 

 preceding, and continuous with the external face of the branches ; it presents : 

 1, On the median line, a slight crest or small groove, traces of its being 

 originally separated into two pieces ; 2, On the sides and above, the mental 

 foramen, the inferior orifice of the maxillo-dental canal. On a level with 

 this foramen, the bone very markedly contracts to form the nech. The 

 circumference describes a parabolic curve, the concavity being uppermost, 

 and joins, by its extremities, the anterior border of each branch. It is 

 excavated in its middle part by the six alveoli for the lodgmeU* of the 



