THE SUPERIOR MAXILLARY BONES. 



83 



The Superior Maxillary Bones or Maxillae. 



The Superior Maxillary (maxilla, the jaw-bone) are the most important bones 

 of the face from a surgical point of view, on account of the number of diseases to 

 which some of their parts are liable. Their careful examination becomes, there- 

 fore, a matter of considerable interest. They are the largest bones of the face, 

 excepting the lower jaw, and form, by their union, the whole of the upper jaw. 

 Each bone assists in the formation of three cavities, the roof of the mouth, the 

 floor and outer Avail of the nasal fossae, and the floor of the orbit, and also enters 

 into the formation of two fossae, the zygomatic and spheno-maxillary, and two 

 fissures, the spheno-maxillary and pterygo-maxillary. 



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

 alveolar, and palate. 



The body is somewhat cuboid, and is hollowed out in its interior to form a 

 large cavity, the ant rum of Highmore. Its surfaces are four an external or 

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



The external or facial surface (Fig. 49) is directed forward and outward. 

 It presents at its lower part a series of eminences corresponding to the position 

 of the teeth. Just above those for the incisor teeth is a depression, the incisive 

 or myrtiform fossa, which gives origin to the Depressor alae nasi ; and below 

 it to the alveolar border is attached a slip of the Orbicularis oris. 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 



Outer Surface. 



TENDO OOUL 



Incisive fossa 



Posterior dental 

 canals. 



Maxillary tuberosity. 



FIG. 49. Left superior maxillary bone. Outer surface. 



it is separated by a vertical ridge, the canine eminence, corresponding to the 

 socket of the canine tooth. The canine fossa gives origin to the Levator anguli 

 oris. Above the canine fossa is the infraorbital foramen, the termination of the 

 infraorbital canal; it transmits the infraorbital vessels and nerve. Sometimes the 

 infraorbital canal opens by two, very rarely by three, orifices on the face. Above 

 the infraorbital foramen is the margin of the orbit, which affords partial attach- 

 ment to the Levator labii superioris proprius. To the sharp margin of bone 



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