342 MAMMALIAN ANATOMY 



into three nearly equal parts : first, and in front, the anterior hori- 

 zontal part of the line of attachment of the maxillo-turbinal ; second, 

 the straight upper horizontal border of the swelling in that attachment 

 which marks the course of the underlying lachrymal canal ; third, the 

 sharp border which runs downward, inward, and backward from the 

 upper lachrymal opening to the rough space for articulation with the 

 maxillary process and with the anterior border of the palatine bone. 

 The lower boundary is the line which marks where the surface passes 

 into the palatine process. It arches from the front outwardly, and 

 ends behind in the upper boundary. The anterior boundary is nearly 

 vertical and irregular and articulates with the premaxillary bone in 

 front. The inner surface is divided into two portions by the lower 

 posterior oblique part of the attachment of the maxillo-turbinal. In 

 front and below this line is a depression for the scroll of the maxillo- 

 turbinal, and behind and above it, a depression for the lower part of 

 the lateral ethmoid. The lower opening of the lachrymal canal is 

 seen at the upper part of this oblique crest. 



The posterior or zygomatic surface (Fig. 272) is little more than 

 a broad rounded border, which forms the maxillary tuberosity. Its 

 upper margin is the posterior margin of the orbital surface ; its lower 

 margin is the posterior margin of the inferior surface ; its outer margin 

 is the posterior margin of the external surface. It is triangular ; one 

 angle is prolonged upward and inward as the common posterior border 

 of the orbital surface and of the inferior surface. Another angle is 

 prolonged upward and outward as the posterior margin of the malar 

 process. The lower blunt angle is the posterior end of the alveolar 

 border. 



The Palatine Plate or Process of the maxillary is very simple ; 

 it springs from the inner side of the body and is directed inward to 

 meet its fellow of the other side, thus forming a greater part of the 

 roof of the mouth and the floor of the nasal chamber. It is flat and 

 thin, its thickness being about uniform throughout its extent. It is 

 slightly thicker, however, at the outside, where its upper surface curves 

 up into the inner or nasal surface, and the lower surface curves down 

 into the alveolar border. It presents three borders for articulation 

 with neighboring bones. 



The anterior border is short, nearly transverse, and serrated. It 

 joins the posterior part of the body of the premaxillary ; a little 



