THE SUPERIOR MAXILLARY BONE. 41 



portion above the palatine process enters into the forma- 

 tion of the outer wall of the nose ; that portion below 

 assists in forming the cavity of the mouth. Above the 

 palatine process, near the posterior border of the bone, 

 is an opening leading into the antrum of Highmore, 

 which is a cavity about the size of a hickory-nut. The 

 opening leading into the antrum is very large and 

 irregular in the disarticulated bone, but, in the articu- 

 lated skull, processes of the turbinated, ethmoid, and 



Bow partly tlftinf 'Or&tet fAmtrmm 

 t*a.rk/d in 



FIG. 18. SUPERIOR MAXILLARY, INNER SURFACE. 



palate bones close in the antrum, leaving only a small 

 orifice, which communicates with the middle meatus 

 of the nose. The nasal mucous membrane is con- 

 tinued through this opening, and lines the antrum. 

 Upon section it is trilateral, frequently subdivided by 

 delicate lamellae of bone, and often presents upon its 

 floor conical projections, which correspond to the apices 

 of the roots of the first and second, and sometimes 

 the last, molar teeth. Its walls are thin and trans- 

 lucent, and, if probes of whale-bone are inserted in the 



