276 ZOOTOMY. 



maxilla and frontal : they often fall out in the dry skull. 

 Each is perforated, near its outer border, by a small aperture 

 for the lacrymal canal. 



70. In the longitudinal section of the skull note the 

 cranial fossae for the reception of the chief divisions of 

 the brain. The hindmost of these, or cerebellar fossa, 

 for the lodgment of rhe cerebellum ( 477), is marked off 

 from the cerebral fossa, for the cerebral hemispheres 

 ( 480), by a sharp oblique ridge along the inner face of 

 the periotic and by the junction of the parietal and supra- 

 occipital; it is along this line that the tentorium ( 162) is 

 attached. The small olfactory fossa, for the olfactory 

 lobes ( 483), is an offshoot of the anterior end of the 

 cerebral, and is marked only by an inconspicuous ridge on 

 the inner surface of the frontal. 



71. The mandible, or lower jaw, consisting of two 

 separate halves, or rami, which articulate with one another 

 in front by a rough surface. Each ramus consists of a 

 horizontal portion, bearing the sockets for the teeth, and of an 

 ascending portion, which ends above in the longitudinally 

 elongated condyle for articulation with the squamosal. 

 Anteriorly the ascending portion gives off the plate-like, 

 slightly incurved coronoid process. The postero-inferior 

 portion, or angle of each ramus, is somewhat produced 

 backwards, and gives off an inward shelf-like projection. 

 On the inner surface of each ramus, at the junction of the 

 horizontal and ascending portions, is the inferior dental 

 foramen, consisting of a number of small apertures and 

 transmitting the third division of the fifth nerve ( 357). 



Interposed between the condyle and the glenoicl cavity is a concavo- 

 convex plate of cartilage, the meniscus. 



72. The hyoid, situated at the root of the tongue, 



