538 



■ THE CEREBRUM. 



In front, the corpus callosnm is reflected downwards and backwards, 

 between the anterior lobes, forming; a bend named the genu (fig. 377, 5). 

 The inferior or reflected portion, which is named tlie rostrum, becomes 

 gradually narrow as it descends, and is connected by means of the 

 lamina cinerea with the optic commissure. It also gives off the two 

 bands of white substance, already noticed as t]\ejJcih(ucJe.<! of the corpus 

 callosnm, which, diverging from one another, run backwards across 

 the anterior perforated space on each side to the entrance of the Syl- 

 vian fissure. 



Behind, the corpus callosum terminates in a free thickened border, 

 the under surface of which is also free for a short distance. 



The under surface of the corpus callosum is connected behind with 

 the fornix, a structure to be presently described, and in the rest of its 



Fig. 077. 



Fig. 377. — View of tue Corpus Callosum fiioji acove (from Sappey after Foville). ^ 



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

 cerebral hemispheres and thro^ving them to the side ; the gyrus fornicatus has been 

 detached, and the transverse fibres of tJio 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 striaj bounding the furrow ; 4, swelling formed by the transverse bands as they 

 pass into the cerebi-um ; 5, anterior extremity or knee of the coriras callosum ; 6, pos- 

 terior extremity ; 7, anterior, and S, 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, fissure between the corpus callosum and its convolution opened 

 out ; outside 12, is the termination of the calloso-marginal fissure, and behind 14 is the 

 parieto-occipital fissure, and between the two the quadrate lobule ; 13, upper surface of 

 the cerebellum. 



