,THE NERVOUS SYSTEM OF MAN. 



33 



human anatomy these are called the corpora quadri- 

 gemina, because they consist of two pairs of rounded emi- 

 nences, but in comparative anatomy they are called the 



cAs 



,-P 



-/7n> 



Fig. 17. — View of brain from below: cr, cerebrum; ce, cerebellum; m, 

 medulla ; p, pons, showing the origins of the nerves ; ol, olfactory, and 

 op, the optic nerves. 



optic lobes, because connected with the sense of sight. 

 They are small and inconspicuous in the human brain, 

 but in the lower vertebrates they may be larger even 

 than the cerebrum. 



5. Thalamus. — Lifting the hinder part of the cere- 

 brum still higher and looking as far forward as possible, 

 we see two pairs of much larger rounded masses. These 

 are the thalamus (the first pair) and the corpus striatum 

 (the second pair). We shall often speak of these to- 

 gether as the thalamus (Fig. 18). 



It would appear, then, but will become far more evi- 

 dent presently, that the spinal cord enters the skull 



