540 



THE CEKEBRUM. 



tinder surface of the cerebrum is concealed by the cerebellum and the pons 

 Varolii. If, however, these parts be removed, it will be seen that the tw o 

 hemispheres of the cerebrum are separated behind as they are in front, by 

 the descent of the great longitudinal fissure between them, and that this 

 fissure is arrested by a cross mass of white substance, forming the posterior 

 extremity of the corpus callosum. This posterior part of the great longi- 

 tudinal fissure is longer than the anterior portion. 



INTERNAL PARTS OF THE CEREBRUM. 



The anatomy of the interior of the cerebrum is most conveniently studied 

 by removing, after the manner of Vieussens and Vicq-d'Azyr, successive 

 portions of the hemispheres by horizontal sections, beginning from above. 



Fig. 



Ik 



Fig. 369. VIEW OP THE CORPUS CALLOSUM FROM ABOVE (from Sappey after Foville). ^ 



The upper surface of the corpus callosum has been fully exposed by separating the 

 cerebral hemispheres and throwing them to the side; the gyrus fornicatus has "been 

 detached, and the transverse fibres of the corpus callosum traced for some distance into 

 the cerebral medullary substance. 



1, the upper surface of the corpus callosum ; 2, median furrow or raphe ; 3, longi- 

 tudinal strise bounding the furrow ; 4, swelling formed by the transverse bands as they 

 pass into the cerebrum ; 5, anterior extremity or knee of the corpus callosum ; 6, pos- 

 terior extremity ; 7, anterior, and 8, posterior part of the mass of fibres proceeding from 

 the corpus callosum ; 9, margin of the swelling ; 10, anterior part of the convolution of 

 the corpus callosum; 11, hem or band of union of this convolution; 12, internal con- 

 volutions of the parietal lobe; 13, upper surface of the cerebellum. 



The first horizontal section, to be made about half an inch above the 

 corpus callosum, displays the internal white matter of each hemisphere, 

 speckled with red spots where its blood-vessels have been divided, and sur- 



