228 



Anatomy of Skeleton 



MAXILLA. 



The bones that make the upper jaw form the main skeleton of the face : each bone 

 is situated below the orbit and beside the nose, forming part of the bony walls of these 

 cavities, and also makes the greater part of the roof of the mouth. It is placed in 

 front of the pterygoid region of the sphenoid, but is of course much wider than this 

 region transversely. 



Each maxilla has a body, below which its alveolar process carries the teeth ; a 

 palatine or horizontal process articulating with its fellow in the middle line below the 

 nasal region ; a nasal process standing up from the front and upper part of the body 

 to articulate with the frontal ; and a rough malar process externally that carries the 

 malar, through which the maxilla is once more connected, indirectly, with the frontal 

 as well as with the temporal. 



The body is roughly a three-sided pyramid, with its base forming part of the outer 

 wall of the nasal fossa and its apex supporting the malar, an upper orbital surface, 



palatine 

 process 



sept*! 



(fat i&l surface) 



FIG. 184. Right maxilla, i. From the front and outer side : the alveolar portion in front, 

 and below the level of origin of Buccinator behind, is covered by mucous membrane and 

 can be examined from the mouth. 2. Posterior surface, showing the part which makes the 

 front wall of the sphenomaxillary fossa and, outside this, the front wall of the zygomatic 

 fossa. 



an anterior facial surface, and a rounded posterior surface. The body is hollow, con- 

 taining the large air sinus known as the antrum of High-more or maxillary sinus, which 

 opens into the nasal fossa. 



The orbital surface, triangular in accordance with the pyramidal conception of the 

 body, is nearly flat, but forms a sloping plane looking upwards and outwards and 

 slightly forwards. It is grooved from behind, forwards and outwards, by the infra- 

 orbital nerve and vessels, the groove ending in front in the infraorbital canal. The 

 surface is in contact with the inferior Rectus and inferior Oblique muscles, the latter 

 arising from it, and is continuous externally with the rough area for the malar. Its 

 anterior border forms a part of the lower orbital margin, the posterior border is the 

 lower margin of the spheno-maxillary fissure, and the inner margin supports the ethmoid 

 except where the orbital process of the palate, at the posterior end of the margin, 

 reaches the floor of the orbit between the two bones : at the front end of the inner 

 margin, just behind the nasal process, is the lachrymal notch, which is made into a 



