THE RHINENCEPHALON 



269 



of it is hidden from view. It includes the lateral olfactory stria and the cortex 

 subjacent to it (or lateral olfactory gyrus), the limen insulce, the uncus, and at 

 least a part of the hippocampal gyrus (Figs. 169, 172, 200). It is not easy to 

 determine just how much of the human hippocampal gyrus should be included. 

 Cajal (1911) apparently includes the entire gyrus, while Elliot Smith (1915) 

 limits it to the part of the gyrus dorsal to the rhinal fissure. In Fig. 200 we 

 have followed the outlines of the hippocampal region as given by Brodmann 

 (1909). 



The Hippocampus. An olfactory center of still higher order is represented 

 by the hippocampus, which was seen in connection with the study of the lateral 



Inferior horn of lateral ventricle 



Hippocampus 



Collateral eminence 



Tapelum 

 Collateral trigone 



Posterior horn of lateral ventricle 



Hippocampal dictations 



,' Uncus 



Dentate fascia of hippocampus 

 Hippocampal gyrus 

 Hippocampal fissure 

 Fimbria of hippocampus 



Bulb of posterior horn 

 Calcarine fissure 



Calcar avis 



Fig. 201. Part of temporal lobe of human brain showing inferior horn of lateral ventricle and the 

 hippocampus. Dorsal view. (Sobotta-McMurrich.) 



ventricle. If we turn again to the floor of the inferior horn of the lateral ven- 

 tricle we shall see a long curved elevation projecting into the cavity (Figs. 181, 

 201). This is the hippocampus and is formed by highly specialized cortex 

 which has been rolled into the ventricle along the line of the hippocampal fissure 

 (Figs. 204, 209). It is covered on its ventricular surface by a thin coating of 

 white matter, called the alveus, which is continuous along its medial edge with 

 a band of fibers known as the fimbria of the hippocampus. This, in turn, is 

 continuous with the fornix (Fig. 201). In Figs. 201 and 204 there may be seen, 

 along the border of the fimbria, a narrow serrated band of gray matter, the 

 fascia dentata, which lies upon the medial side of the hippocampus. It is sepa- 

 rated from the hippocampal gyrus by a shallow groove, called the hippocampal 



