250 



THE NERVOUS SYSTEM 



by the following structures, named in their order from within outward: the 

 fimbria, hippocampus, and (in man) the collateral eminence (Figs. 181, 182, 

 189). Upon the fimbria and hippocampus there is superimposed the chorioid 

 plexus (Fig. 183). The hippocampus is a long, prominent, curved elevation, 

 with whose medial border there is associated a band of fibers, representing a 

 continuation of the fornix and known as the fimbria. These parts will be de- 



Lamina of septum pellucidum 



Columns of fornix 

 Anterior tubercle of thala- 



Uncus. 



Hippocampal 

 digitations\ 



Hippocampal,. 

 gyrus 



Collateral eminence 

 Fimbria of hippo- 

 campus . 

 Collateral trigone 

 Posterior commissure 



Hippocampus 



Calcar avis 

 Posterior horn of lateral ventricle 



f Longitudinal fissure of cerebrum 

 Corpus callosum 



, Cavity of septum pellucidum 

 Interventricular foramen 

 Anterior horn of lateral ventricle 

 Head of caudate nucleus 



,Massa intermedia 

 , Third ventricle 

 , Habenular commissure 



,-Habenular trigone 



^Inferior horn of lateral 

 ventricle 



Posterior horn of lat- 

 eral ventricle 



Pineal body 



Corpora quadrigemina 

 Vermis of cerebellum 



Fig. 181. Dissection of the human brain to show the posterior and inferior horns of the lateral 

 ventricle. The body and splenium of the corpus callosum have been removed, as have also the body 

 of the fornix and the tela chorioidea of the third ventricle. A sound has been passed through the 

 interventricular foramina. Dorsal view. (Sobotta-McMurrich.) 



scribed in connection with the rhinencephalon. The collateral eminence is an 

 elevation in the lateral part of the floor produced by the collateral fissure. 



The thin epithelial membrane, described above as joining the edge of the 

 fornix with the caudate nucleus (Fig. 155), continues to unite these structures as 

 they both curve downward, the former in the floor, the latter in the roof, of the 

 inferior horn. A vascular plexus from the pia mater is invaginated into the 



