THE FACE 335 



the external surface is rough and overlaps the nasal surface of the 

 maxillary ; an extension forward, sometimes called the maxillary pro- 

 cess, covers part of the nasal orifice of the maxillary antrum (Fig. 

 260). 



The small sphenoidal process rises from the top of the posterior 

 angle and curves upward and inward. Its superior surface is applied 

 to the lower surface of the spheno-turbinal of the sphenoid, and is 

 marked by a longitudinal groove which the sphenoid converts into the 

 pharyngeal canal. Its external surface is bevelled behind for the 

 internal pterygoid plate, and is smooth in front where it forms part 

 of the wall of the spheno-maxillary fossa. The internal surface is 

 concave, and is part of the wall of the nasal cavity. The anterior 

 border is the posterior border of the spheno-palatine notch, sometimes 

 a true foramen, but usually converted into one by the spheno-turbinal. 



Above and in front of the notch is the ethmoidal, or orbital, 

 process, which is quadrate and more or less hollow. Although small, 

 it presents five surfaces, whereof two are non-articular, namely, the 

 superior, or orbital, which forms a small area on the posterior medial 

 wall of the orbit, and the external, or zygomatic, which enters into 

 the superior-anterior wall of the spheno-maxillary fossa and hence 

 faces outward and backward toward the zygomatic fossa. Of the 

 articular surfaces, the anterior-inferior joins the maxillary, the 

 posterior-superior joins the outer edge of the spheno-turbinal, and 

 the internal, or ethmoidal, faces upward, forward, and inward to join 

 the lateral ethmoid. The cavity in the interior of the ethmoidal 

 process opens widely, sometimes on the posterior-superior surface, 

 sometimes on the internal surface. 



The small palatine plate presents few noteworthy features. The 

 median margins of both the superior and inferior surfaces are raised 

 into strong crests. The inferior surface exhibits close to its outer 

 margin the openings of the posterior palatine and accessory posterior 

 palatine canals ; the latter can be traced upward to the inner and 

 posterior wall of the main canal. 



THE MAXILLARY BONES. 



General Description. The Maxillaries are paired bones which 

 form the greater part of the upper jaw and of the face. They con- 

 tribute also largely to the outer walls and the floor of the nasal chain- 



