THE CEREBRAL HEMISPHERES 



789 



oIfnP+Jri,!m th» olfactory striiB go to the piriform lobe and hippocampus, the trigonum 



fnttl crnpi^f^r^^r'^f *?"^' ^^^ subcallosal gyrus, and part of the gyrus fornicatus The 

 an^Prfnr .pX r *^^ olfactory apparatus are complex and are not yet fully understood. The 

 wW the S commissure contams fibers which pass from the olfactory bulb of one side by 

 mtninl =t^-i^ f ^""^ *? ^^t ^" ''..°^ ^^^ opposite side; also fibers which cross in it from the 

 hinr,np/^nn= K °'''' '"'^M" ^^^ P'^form lobe of the opposite side. Many fibers pass to the 

 T^u^n^F^L/ ^■''l °lu^^ ^^^""^ pellucidum, fornix, and fimbria. Other fibers pass in the 

 mm^ bundle mammiUary body and thence to the thalamus by the thalamo-mam- 



The corpus callosum is the great transverse commissure which connects the 

 two cerebral hemispheres through about half of their length. On median section 



'Olfactory bulb 



' ' Cortex cerebri 



Corpus medullar e 

 I — Caudate nucleus 



Chorioid plexus 

 f^ ~ Fornix 



Hippocampus 



FiG. 642. — Bhain of Hobse, with Latebal Venthicles Opened by Removal op Uppee Paet of Cerebeal 

 Hemibphebes and Most of the Corpus Callosum. 



(Fig. 639) it is seen to be arched from before backward, white in color, and com- 

 posed substantially of transverse fibers. The middle part or trtincus (Truncus 

 corporis callosi) slopes downward and forward and is thinner than the ends. The 

 anterior thickened end, the genu, bends ventrally and backward and thins out to 

 form the rostrum ; the latter is continuous with the lamina terminalis. The pos- 

 terior end, the splenium, also thick, lies at a considerably higher level than the 

 genu. The dorsal surface is convex in its length, concave transversely; it forms 

 the floor of the longitudinal fissure. It is covered by a thin layer of gray matter 

 (Induseum griseum), in which are strands of longitudinal fibers (Striae longitudi- 

 nales) ; the latter are arranged in medial and lateral bundles (Stria medialis, striae 



