SUPERIOR MAXILLARY BONE. 



159 



SUPERIOR MAXILLARY BONE. 



The Superior Maxillary is one of the most important bones of the face in a 

 surgical point of view, on account of the number of diseases to which some of 

 its parts are liable. Its minute examination becomes, therefore, a matter of 

 considerable interest. It is the largest bone of the face, excepting the lower jaw; 

 and forms, by its union with its fellow on the opposite side, the whole of the 

 upper jaw. Each bone assists in the formation of three cavities, the roof of 

 the rnouth, the floor and outer wall of the nose, and the floor of the orbit ; and 

 also enters into the formation of two fossae, the zygomatic and spheno-maxil- 

 lary; and two fissures, the spheno-maxillary and pterygo-maxillary. 



The bone presents for examination a body and four processes, malar, nasal, 

 alveolar, and palatine. 



The Body is somewhat quadrilateral, and is hollowed out in its interior to 

 form a large cavity, the antrum of Highmore. Its surfaces are four : an ex- 

 ternal or facial, a posterior or zygomatic, a superior or orbital, and an internal. 



The external or facial surface (Fig. 112) is directed forwards and outwards. 

 In the median line of the bone, just above the incisor teeth, is a depression, the 



Fig. 112. Left Superior Maxillary Bone. Outer Surface. 

 Outer Surface. 



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Incisive fossa- 



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incisive or myrtiform fossa, which gives origin to the Depressor Alas Nasi. 

 ; Above and a little external to it, the Compressor Nasi arises. More external, 



is another depression, the canine fossa, larger and deeper than the incisive fossa, 



from which it is separated by a vertical ridge, the canine eminence, correspond- 

 ' ing to the socket of the canine tooth. The canine fossa gives origin to the 

 I Levator Anguli Oris. Above the canine fossa is the infra-orbital foramen, the 

 | termination of the infra-orbital canal; it transmits the infra-orbital nerve and 

 | artery. Above the infra-orbital foramen is the margin of the orbit, which 

 | affords partial attachment to the Levator Labii Superioris Proprius. 



The posterior or zygomatic surface is convex, directed backwards and out- 

 ! wards, and forms part of the zygomatic fossa. It presents about its centre 



several apertures leading to canals in the substance of the bone ; they are 



