PHYSIOLOGY FOR DENTAL STUDENTS. 



parts of the brain. The optic thalamus, as its name signifies, is 

 intimately associated with the optic nerves. 



Another important collection of nerve cells occurs in the 

 corpora quadrigcniina. These exist as four rounded swellings, 

 two on either side, just where the superior peduncles of the cere- 

 bellum come together. Their nerve cells serve as distributing 

 centers for visual and auditory impulses, carried to them through 

 tracts of nerve fibers connected with the optic and auditory 



P 



Fig. 46. Vertical transverse section of human brain. Below is a section 

 of the pons (P) showing the fibers which connect the brain stem and cere- 

 brum radiating up through the internal capsule (1C), which is bounded 

 mesially by the optic thalmus (T), and laterally by the corpus striatum (L). 

 The third (III-V) and lateral ventricles (LV) of the brain are seen in the 

 center (black). The thickness of the grey matter and the infolding of the 

 surfaces, as convolutions, should be noted. (From a preparation by 1'. M. 

 Spurney. ) 



nerves. The corpora quadrigemina are usually more developed 

 in the brain of the lower animals than in that of man. 



The Cranial Nerves. On account of the introduction of 

 the new structures described above there is no regularity in the 



