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PHYSIOLOGY FOR BEGINNERS 



brain. These columns diverge from one another as they pass 

 forwards to the two largest masses of the brain, the cerebral 

 hemispheres. On the upper side of the crura cerebri the 

 brain substance is raised up into two pairs of rounded masses 

 called the corpora quadrig-emina. In front of these are 



FIG. 85. The base of the brain. 



A, The anterior or frontal lobe of the right cerebral hemisphere ; />', the lateral or 

 temporal lobe ; Cb, the cerebellum ; Af, medulla oblongata ; 1. to XII., the twelve 

 cranial nerves ; CC, part connecting the two hemispheres together, /', ib placed 

 just in front of the crossing or chiasma of the optic nerves. 



two larger masses, one on either side, called the optic tha- 

 lami, into or past which most of the fibres of the crura 

 cerebri go. The cerebral hemispheres are two large masses, 

 one on each side, separate from each other, except where they 

 are joined together by a flattened band of nerve fibres running 



