GENERAL ANATOMY OF THE NERVOUS SYSTEM 71 



which overlie them. Thus we speak of the frontal, the 

 parietal, the temporal, and the occipital regions or lobes. 

 The principle would entitle us to refer also to the sphe- 

 noidal and ethmoidal areas, but these terms are seldom 

 heard. The word "lobe," often used with reference to 

 these organs, is, perhaps, somewhat misleading. It sug- 

 gests a degree of isolation more marked than that which 

 actually obtains. The temporal portion deserves this 

 designation more clearly than do the others, since it is 



Medulla. 



Oblon^aCa 



Fig. 13. The human brain, from the left (Morrow). 



quite distinct set off by a cleft of exceptional depth, the 

 fissure of Sylvius. On first glancing at a figure of the 

 cerebrum one recognizes which direction is anterior by the 

 presence of the temporal lobe, pointing downward and 

 forward (Fig. 13). 



The Cranial Nerves (Fig. 14). Twelve pairs of nerves 

 are united with the human brain. It has already been 

 stated that only one of these, the pair mediating the sense 

 of smell, is joined directly to the cerebrum. These bundles 

 of fibers entering the under surface of the hemispheres 



