THE CEREBRUM 



465 



passes downwards, in a nearly vertical direction, on the medial 

 surface of* the hemisphere, as a conspicuous and deep cleft, 

 which, at its lower end, joins the calcarine fissure. 



Fissura Collateralis (Fig. 187). The collateral fissure is a 

 strongly marked fissure on the tentorial part of the inferior 

 surface of the cerebral hemisphere. It begins near the 

 occipital pole, and extends anteriorly towards the temporal 

 pole. Posteriorly it lies below and parallel to the calcarine 



Central sulcus 



Callosal sulcn 



Parieto-occipi 

 "ssure 



ulcus cinguli (O.' 

 Calloso-marginal) 



Genu of corpus callosum ' 



Septum pellucidum I 



Anterior commissure 



Fornix 



\ Calcarine fissu 

 Subparietal sulcus 



\ \ \ \ Stem of calcarine fissure 

 \ \ \ Splenium of corpus callosum 

 * \ Isthmus 

 v Inferior temporal sulcus 

 Collateral fissure 



Mamillary body 



FIG. 187. The Gyri and Sulci on the Medial and Tentorial 

 Aspects of the Cerebral Hemisphere. 



fissure, whilst anteriorly it is separated from the hippocampal 

 fissure by the hippocampal gyrus, which is the highest and 

 most medial convolution on the tentorial part of the inferior 

 surface of the hemisphere (Fig. 187). 



Anterior to the collateral fissure a shallow sulcus turns 

 round the anterior end of the temporal lobe and intervenes 

 between the temporal pole and the uncinate or hook-like 

 extremity of the hippocampal gyrus. This is the indsura 

 temporalis or ecto-rhinal fissure (Fig. 188). 



Sulcus Cinguli (O.T. Calloso marginal Fissure) (Fig. 187). 

 This is a strongly marked sulcus on the anterior part of 



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