INFERIOR MAXILLA. 63 



and each presents for consideration two surfaces, two borders, 

 and two extremities. 



The external surface is smooth and rounded anteriorly, growing 

 gradually deeper as its proceeds backwards ; the posterior part or 

 curved portion is roughened and excavated for the attachment of 

 the inasseter muscle. The internal surface is roughened and 

 hollowed posteriorly, for the attachment of the pterygoid muscles, 

 and its presents a large foramen, the inferior maxillary or dental, 

 leading to the dental canal, which passes through the bone below 

 the roots of the molar teeth. The anterior part of the surface is 

 smooth and flat, and has a groove for the attachment of the 

 buccal membrane ; below the groove, some of the muscles of the 

 tongue are attached. 



The superior border is straight anteriorly, and concave pos- 

 teriorly ; the first part contains six alveoli for the lower molars, 

 and the second, which terminates in thecoronoid process, is thin, 

 and roughened for muscular attachment. The inferior border 

 is also divided into two portions, a straight and a convex one, 

 separated by a prominent roughened part termed the angle of the 

 jaw. The anterior portion is rounded in the young animal, but 

 grows gradually thinner with age owing to the outward growth of 

 the teeth ; the posterior border above the angle becomes thinner, 

 and terminates in the condyle. 



The posterior extremity presents two eminences, a flat, thin, 

 pointed one, the coronoid process, anteriorly, and a transverse 

 doubly convex one, the condyle, posteriorly, the two being separated 

 by a deep notch, the sigmoid or corono-condyloid. The anterior 

 extremities, joined by the maxillary symphysis, form the body of 

 the bone. The external or labial surface of the body is convex, 

 and gives attachment to the gums and labial muscles, and has a 

 line down its middle, which marks the division of the foetal bone. 

 The internal or buccal surface, less than the external, is smooth 

 and concave ; the frasnum of the tongue is attached to its poste- 

 rior part. The anterior border is excavated into six alveolar 

 cavities for the incisor teeth ; and on each side, farther back, it 

 presents, in the male animal, a cavity for the canine tooth, small 

 or absent in the female. The neck is the constricted portion 

 which joins the body to the ramus, and it has a more or less 

 sharp ridge, superiorly ; these ridges, or bars, occupy the inferior 

 diastema or interdental space. On the outer side of the neck is 

 the anterior maxillary, mental, or labial foramen, the termina- 



