160 THE SKELETON. 



termed the posterior dental canals, and transmit the posterior dental vessels and 

 nerves. At the lower part of this surface is a rounded eminence, the maxillary 

 tuberosity, especially prominent after the growth of the wisdom-tooth, rough 

 on its inner side for articulation with the tuberosity of the palate bone. Im- 

 mediately above the rough surface is a groove, which, running obliquely down 

 on the inner surface of the bone, is converted into a canal by articulation with 

 the palate bone, forming the posterior palatine canal. 



The superior or orbital surface is thin, smooth, triangular, and forms part of 

 the floor of the orbit. It is bounded internally by an irregular margin which 

 articulates, in front, with the lachrymal ; in the middle, with the os planum of 

 the ethmoid; behind, with the orbital process of the palate bone; bounded 

 externally by a smooth rounded edge which enters into the formation of the 

 spheno-maxillary fissure, and which sometimes articulates at its anterior ex- 

 tremity with the orbital plate of the sphenoid ; bounded, in front, by part of 

 the circumference of the orbit, which is continuous, on the inner side with the 

 nasal, on the outer side with the malar process. Along the middle line of the 

 orbital surface is a deep groove, the infra-orbital, for the passage of the infra- 

 orbital nerve and artery. This groove commences at the middle of the outer 

 border of the surface, and passing forwards, terminates in a canal which sub- 

 divides into two branches; one of the canals, the infra-orbital, opens just be- 

 low the margin of the orbit ; the other, which is smaller, runs into the substance 

 of the anterior wall of the antrum ; it is called the anterior dental canal, trans- 

 mitting the anterior dental vessels and nerves to the front teeth of the upper 

 jaw. At the inner and fore part of the orbital surface, just external to the 

 lachrymal canal, is a minute depression, which gives origin to the Inferior 

 Oblique muscle of the eye. 



The internal surface (Fig. 113) is unequally divided into two parts by a hori- 

 zontal projection of bone, the palate process; the portion above the palate pro- 

 Fig. 113. Left Superior Maxillary Bone. Inner Surface. 



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cess forms part of the outer wall of the nose ; that below it forms part of the 

 cavity of the mouth. The superior division of this surface presents a large 



