870 



THE NERVOUS SYSTEM 



pellucidum to the lower surface of the corpus callosum. BelOw, it lies over the 

 chorioid tela of the third ventricle, which separates it mesially from the cavity 

 of the third ventricle and laterally from the upper surfaces of the thalami. Its 

 sharp lateral edge or margin (taenia fornicis) projects into the lateral ventricle 

 of either side in relation with the chorioid plexus of that ventricle, and thus the 

 lateral portion of its upper surface forms part of the floor of the lateral ventricle — 

 an arrangement to be expected, since the posterior pillars arise from the floor of 



Fig. 684. — Horizontal Section of Telencephalon showing Body of Fornix and Hippo- 

 CAMPAL Commissure as seen from Below and the Anterior Commissure in Section. 

 (After Toldt, "Atlas of Human Anatomy," Rebman, London and New York.) 



Genu of corpus callosum 



Covered portion of col 

 umns of fornix 



Insula 



Temporal lobe 



Lateral cerebral fissure 

 (SylvU) 



Claustrum ->-_ 

 External capsule-^'; 



Free portion of col- 

 ums of fornix 



Interventricular fora- 

 men (Monroi) 



Parolfactory area (Brocae) 

 Triangular recess //U 



Rostrum of corpus callosum 

 fir>>' Head of caudate nucleus 



1 "ii^ii ^v Putamen of lenticular nucleus 



Anterior cerebral 

 commissure 



Globus pallidus 



Habenular nucleus 



Tail of caudate 

 nucleus 



Inferior cornu of lat- 

 eral ventricle 



Parieto-occipital fissure 



'vHippocampal com- 

 missure 



Splenium of corpus 

 callosum 



Longitudinal fissure 



Medial surface of hemisphere 



Cuneu 

 Calcarine fissure 



the ventricle, viz., the hippocampus. The ventricular portion is covered by a 

 layer of ependyma in common with that lining the rest of the ventricle. 



Along its body the fornix receives fibres arising from the cells of the cortex of the gyrus 

 cinguli and fibres from the longitudinal striic upon the dorsal surface of the corpus caUosum. 

 These are known as the perforating fibres of the fornix. In their ventral course, they pass ob- 

 liquely forward through the corpus callosum and, anteriorly, tlirough the posterior angle of the 

 septum pellucidum to join the fornix and course in its functional direction. The fibres arising 

 in the cortex of the gyrus cinguli may course short distances in the cingulum before perforating 

 the oorpus callosum. 



The columns or anterior pillars of the fornix [columnae fornicis], are two separ- 

 ate, cylindrical bundles wliicii pass forward from the apex of the body of the fornix 

 and then turn sharply downward along the anterior boundary of the third ven- 

 tricle, just behind tlie anterior ccrel^ral commissure. A part of each column, the 

 /ree jwrlion [])ars libera], forms the anterior boundary of the interventricular 

 foramen (Monroi). Thence; the covered portion [pars tecta] sinks into the grey 



