630 



THE NEKVOUS SYSTEM. 



length. The corpus callosum is highly arched from before backwards, and 

 presents a convex superior surface and a concave inferior surface when viewed from 

 the side (Fig. 558). 



The superior surface of the corpus callosum forms the bottom of the longi- 

 tudinal fissure, and on each side of this it is covered by the gyrus cinguli. Only 

 in its posterior part is it approached by the falx cerebri ; in front, this process of 

 dura mater falls considerably short of it. The superior surface of the corpus callosum 

 is covered by a thin layer of indusium continuous at the bottom of the sulcus 

 corporis callosi with the gray cortex on the surface of the hemisphere. In this there 

 are embedded, on each side of the median plane, two delicate longitudinal bands 

 of fibres, called respectively the stria longitudinalis medialis and lateralis. The 

 stria longitudinalis medialis is the more strongly marked of the two, and it is 

 separated from its fellow of the opposite side by a faint median furrow. The 

 stria longitudinalis lateralis is placed farther out, under cover of the gyrus 



Sulcus cinguli 

 Gyrus cinguli 

 Commissura fornicis 

 Corpus fornicis j 



Corpus callosum 

 Septum pellucidum 

 Sulcus cinguli * ^ 



Paracentral area 

 j Paracentral sulcus 

 I Sulcus centralis 



Hippocampal rudiment 

 Incisura sulci cinguli 



'Sulcus prsecunei 

 .Prsecuneus 



.Sulcus subparietalis 



Fossa parieto- 

 ''occipitalis 



Sulcus paramedia 

 -A.rea striata 



Gyrus frontalis superior 

 Lamina chorioidea 



Foramen 

 interventriculareX 



Genu of 



corpus 



callosum 



Rostrum of 

 corpus 

 callosum 

 Sulcus.^^Sj 



genualis jj^j 



AnteriorjSjffl 



commissure VT 



Olfactory bulb 

 Corpus paraterminalfc" 



Columna fornicis / 

 Olfactory tract 

 Stria olfactoria lateralis / 



Nucleus amygdalae / 

 Piriform area 



Thalamus (cut surface) ', 



Rhinal fissure \ | 

 Cauda fasciae dentatse | 



\ \ Sulcus polaris inferior 

 '* v Sulcus calcarinus 

 Sulcus sagittalis gyri lingualis 

 Sulcus col lateralis 

 , \ i Hippocampus 

 \ l Splenium of corpus callosum 

 \ Fascia dentata 



Crus fornicis 

 Gyrus paradentatus 



Hippocampus Fimbria 

 FIG. 558. THE MEDIAL ASPECT OF THE RIGHT CEREBRAL HEMISPHERE. 



cinguli. The thin coating of gray matter, with the two striee, represents the 

 aborted remains of the hippocampus (see p. 627). So thin is this gray coating that 

 the transverse direction pursued by the callosal fibres proper can be easily perceived 

 through it. 



The two extremities of the corpus callosum are much thickened, whilst the 

 intermediate part or body is considerably thinner. The massive posterior end, 

 which is full and rounded, lies over the mesencephalon and extends backwards as 

 far as the highest point of the cerebellum. It is called the splenium, and it consists 

 of a superior and inferior part. The latter is bent forwards under the upper part, 

 to the inferior surface of which it is closely applied. The anterior end of the corpus 

 callosum is not quite so massive, and it is folded downwards and backwards on 

 itself. It is termed the genu. The recurved inferior part of the genu is separated 

 from the part of the corpus callosum which lies above, by an interval. It rapidly 

 thins as it passes backwards and receives the name of the rostrum. The fine 

 terminal ~edge of the rostrum becomes connected by means of a band of neuroglial 



