50 



THE BONES OE THE HEAD. 



THE SUPERIOR MAXILLARY BONE. 



The upper jaw, superior maxilla, is the principal bone of the face ; it supports 

 all the teeth of the upper range, and takes part in the formation of the hard palate, 

 the floor of the orbit, and the floor and lateral wall of the nasal cavity. It consists 

 of a central part or body, and four processes. The body presents an external 

 surface, which is again subdivided into anterior or facial, and posterior or zygomatic 

 portions ; an internal or nasal surface, and a superior or orbital surface. The pro- 

 cesses are the nasal or ascending, projecting upwards from the fore part of the 

 body, the alveolar, forming the lower border of the bone and containing the alveoli 

 or sockets for the teeth, the malar on the outer aspect, separating the facial and 



NASAL 



OCES5 



INFRAORB. GROOVE 



Fig. 50. RIGHT SUPERIOR MAXILLARY BONE : OUTER VIEW. (Drawn by D. Gunn.) 



zygomatic surfaces, and the palate process, projecting horizontally on the inner side. 

 The body is farther excavated by a large sinus or antrum, which opens on the inner 

 side into the nasal fossa. The superior maxillary bone articulates with its fellow, 

 with the nasal, frontal, lachrymal, ethmoid, palate, malar, vomer, and inferior tur- 

 binate bones, and sometimes with the sphenoid. 



The facial surface is marked at the lower part, where it is continuous with the 

 outer surface of the alveolar process, by a series of eminences corresponding in 

 position to the fangs of the teeth ; that of the canine is particularly prominent, and 

 internal to this is a slight depression, the incisor or myrtiform fossa ; while between 

 it and the malar process is the deeper canine fossa. Above the canine fossa, and 

 close below the margin of the orbit, is the infraorUtal foramen, by which the infra- 

 orbital nerve and artery issue. The inner margin of this surface is deeply excavated 

 by the nasal notch, the sharp edge of which is produced below into the anterior 

 nasal spine. 



The zygomalic surface looks into the zygomatic and spheno-maxillary fossee ; it is 

 convex, and presents about the centre one, two or more apertures of the posterior 

 dental canals, transmitting the vessels and nerves of that name ; the lower and- 

 posterior part of this surface is prominent and rough, and is distinguished as the 

 tulerosity. 



