INFERIOR MAXILLA. 63- 



eacli presents for consideration two surfaces, two borders, and 

 two extremities. 



The external surface is smooth and rounded anteriorly, growing 

 gradually deeper as it proceeds backwards ; the posterior part or 

 curved portion is roughened and excavated for the attachment of 

 the masseter muscle. The internal surface is roughened and 

 hollowed posteriorly, for the attachment of the pterygoid muscles, 

 and it 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 this 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 

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

 and the second, which terminates in the coronoid 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 j^oung animal, 

 but grows gradually thinner with ago owiag 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 notcb,^ the sigmoid or corono-condyloid. The anterior 

 extreinities, 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 fr^num 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 bay's, occupy 

 the inferior diastema or interdental space. On the outer side 

 of the neck is the anterior maxillary, mental, or labial foram^n^. 



