(586 



A TEXTBOOK OF PHYSIOLOGY 



and the pons. The cerebellum lies dorsally to the pons, which bridges 

 its two hemispheres, covering the brain-stem as it ascends from the 



roof plate pineal 



optic, thalam, 

 caudate nucleus 



mid brain 

 corp. quad. 



lam. terminalis 

 offset lobe 



sulcus of Monro 

 cor/o. mam. 



hijpothalam. part 3rd uent 

 tuber ciner. 



nose 



neural part of pituitary 

 buccal pituitary 

 \' \~phar. 



FIG. 412. SCHEMATIC FIGURE TO SHOW THE PARTS DEEIVED FROM THE WALLS OF 

 THE FORE-BRAIN. (Keith, after His.) 



bulb to mid-brain. In the region of the bulb and pons, the central 

 canal of the spinal cord opens out, to form the-lozenge-shaped fourth 

 ventricle of the brain. 



The mesencephalon consists, in the adult brain, 

 mainly of the limbs (crura) of the great brain, and 

 the four bodies known as the corpora quadrige- 

 mina. Through it runs the central canal, here 

 knowii as the aqueduct of Sylvius. The optic 

 lobes of the lower animals are associated with this 

 part of the brain. 



The diencephalon, or thalamencephalon, de- 

 velops into the optic thalami and the parts en- 

 closing the third ventricle of the brain. From 

 FROG'S the primary vesicle, of which this is the hinder 

 part, there arise lateral expansions the optic 

 vesicles, which go to form the retinae and optic 

 tract of the adult animal. These form close con- 

 tSmencephalon'; nections with the optic thalami and with the 

 5, optic lobe; G, corpora quadrigemina of the mid-brain, 

 cerebellum;?, The prosencephalon expands forwards and 

 and r .meduUft Tb- downwards at first, and then from the lateral 

 longata. aspects large hollow outgrowths arise the cerebral 



hemispheres. The dorsal and lateral walls of 

 these hemispheres become greatly thickened internally with white 

 matter, and externally with a grey cortex, and thus the great brain 



FIG. 413. DIAGRAM 



OF THE 



BRAIN. 



1, Olfactory lobs; 

 2. cerebrum ; 3, 



