364 



PHYSIOLOGY 



front piercing the corpus striatum between its two nuclei. It is called the 

 internal capsule. 



The development of the different parts of the brain stem from the 

 three cerebral vesicles and their gradual subordination and overshadowing 

 in the course of development by the cerebral hemispheres is well shown if we 



Lamina terminalis 



Optic recess 



Optic nerve 



Optic commissure 



Hypophysis 



Anterior commissure 

 Foramen of Monro 



3rd nerve 

 Corpus mammillare 



3rd ventricle 

 Cerebral peduncle 

 Pons 



FIG. 179. 



Suprapineal recess 



Pineal body 



i oiiyenur meu unary 

 Cerebral aqueduct ' Corpora quadrigemina 



Median section of an adult human brain 



\ Cerebellum 



\ Medulla oblongata 

 4th ventricle 

 Superior medullary velum 



(J. SYMINGTON.) 



compare the brain of a fish with that of a reptile and again with that of 

 a mammal (Fig. 180). Man's position in the scale of animal life is determined 

 not by increasing complexity of the structures forming his brain stem, but by 

 the gradual subordination of these to the latest formed cerebral hemispheres, 

 and the enormous growth of his capacity to adapt himself to a varying 

 environment consequent on the increase in size of his cerebral hemispheres. 



