THE FACE 



387 



FIG. 308. 



and joins the uncinate process of the ethmoid. The superior border 



is prolonged outward and downward as a broad maxillary process, 



which, with the border itself, is 



fastened to the inner surface of the 



nasal process of the maxillary bone, 



partially closing the opening of the 



antrum (Fig. 281). 



RIGHT TURBINAL BONE, EXTERNAL VIEW. 



1, anterior extremity, articulating with the max- 

 illary ; 2, posterior extremity, articulating with the 

 palatine bone; 3, hook-like maxillary process, articu- 

 lating with the lower border of the maxillary an- 

 trum. Above are the lachrymal and ethmoidal 

 processes ; 4, inferior obtuse border. 



THE MANDIBLE. 



General Description. The 



Mandible, or Lower Jaw, is a V- 

 shaped arch of bone which forms 



the inferior boundary of the mouth (Fig. 309). Its free extremities 

 are articulated to the temporal bone of the skull. Its apex forms 

 the chin. In its upper border are planted the lower teeth. Each 

 half of the arch consists of a separate bone, meeting its fellow in front 

 at an angle of about fifty degrees and in the natural state joined with 

 it by an immovable articulation or symphysis (Fig. 310) ; upon macera- 

 tion the two sides fall apart. They may be called the right and left 

 inferior maxillary bones, or the right and left halves of the mandible. 

 Each half is a bony bar compressed from side to side and consisting 



FIG. 309. 



THE FACE. 



A, side view of the skull, bones of the face black. B, diagrammatic transverse section, showing relations of the 



nasal cavity, JV, the orbital cavities, O, and the mouth, M. 



of two parts (Fig. 311), an anterior, longer, more slender, horizontal 

 ramus, or body ; and a posterior, shorter, more elevated part, called 

 the ascending ramus. The two parts are not sharply denned, the 

 surfaces and borders of one passing without material change of form 

 or direction into the corresponding surfaces and borders of the other, 

 but all the bone in front of the last tooth is regarded as body, and 

 all behind and above it as ascending ramus. 



