THE SKULL AS A WHOLE 



179 



shorter folds decreasing in length from above downward. In the 

 natural condition, the turbinated bones bear a considerable portion 

 of the nasal epithelium, the surface of which is greatly increased 

 by the folding of the underlying bone. That covering the ethmo- 

 turbinal contains the olfactory sense organs, while that covering 

 the maxilloturbinal is non-sensory and possesses the mechanical 

 function of freeing the air of the respiratory tracts from foreign 

 materials, as well as of warming it slightly in its passage. On this 

 account the respective structures are conveniently distinguished 

 as sensory (olfactory) turbinals and respiratory turbinals. 



The mandible (mandibula) is composed of two portions, united 

 anteriorly by the symphysis mandibulae. Each half comprises 



d.i. 



Fig. 89. Lateral surface of the left hand of the mandible: a.m., angle; 

 cm., body of mandible; cp.m., articular portion (head) of mandible; d.i., d.m., 

 and d.pm., incisor, molar, and premolar teeth; f.m., mental foramen; i.m.a. 

 and i.m.p., anterior and posterior mandibular incisures; p.c, coronoid process; 

 p.cd., condyloid process; t.m. and t.pt., masseteric and pterygoid tuberosities. 



a horizontal portion, forming in conjunction with that of the 

 opposite side the body of the mandible (corpus mandibulae), and a 

 posterior, vertical portion, the ramus mandibulae, the latter 

 serving for the insertion of the muscles of mastication and for 

 articulation with the skull. The body of the mandible bears on 

 its dorsal margin the alveoli of the lower teeth. The mandibular 

 ramus forms a broad plate, the latera^l surface of which is occupied 

 in the intact animal by the masseter muscle, while the medial 

 surface forms an area of insertion for the external and internal 

 pterygoids. The surface of the ramus is greatly increased in its 

 postero ventral portion through the expansion of the bone to form 



