THE FACE 



371 



FIG. 290. 



Premax' 



slightly roughened for articulation, throughout its extent, with the 

 opposite bone. It is triangular, but the inferior angle, or apex, is 

 truncated and rounded 

 posteriorly. The supe- 

 rior part, or base, is 

 arcuate, especially be- 

 hind, following the out- 

 line of the convex 

 superior border. The 

 anterior margin is sin- 

 uate, slightly arcuate 

 above, and emarginate 

 below. The posterior 

 margin is emarginate 

 above and arcuate 

 below ; it enters into 

 the formation of the 

 nasal crest. 



The external sur- 

 face (Fiff ^92) is the TRANSVERSE VERTICAL SECTION THROUGH HALF OF FACE. 



1 . -, y Five millimetres anterior to Infraorbital Foramen. Cut surfaces 



niOSt Complicated. ItS black. (Somewhat diagrammatic.) 



shape is about that of 



the inner surface ; it is more pointed, however, at the lower end, where 

 it is continued as the outer margin of the external angle. The upper 

 half, or more, is occupied by a flat, oval, ethmoidal fossa. The lower 

 half is narrow and largely the outer part of the outer margin of the 

 posterior surface, which is rolled downward. The ethmoidal fossa is 

 limited above by a crescentic rough space, which, with the upper half 

 of the sharp anterior margin, articulates with the median surface of 

 the nasal process of the frontal. The posterior margin begins at the 

 posterior lower end of this crescentic space and passes downward, 

 becoming gradually higher and rolling backward at the lower end ; 

 it leaves between the edge of the fossa and the edge of the bone a 

 shelving smooth surface. The fossa is extended into the interior of 

 the bone to a greater or less degree. The inner, upper anterior scroll 

 of the lateral ethmoid (Fig. 290) is contained in this fossa, and a 

 plate lying below it, the partition of the mesial scroll (m), is attached 

 to the posterior margin of the surface, almost down to the angular 



