THE CEREBRUM 



441 



Cavum Septi Pellucidi (O.T. Fifth Ventricle). The cavity 

 of the septum pellucidum is the name applied to the median 

 cleft between the two laminae of the septum. It varies greatly 

 in extent, in different brains, and it contains a little fluid. It is 

 completely isolated, having no communication either with the 

 ventricles or with the exterior. 



Fornix. The fornix is an arched structure, composed of 

 longitudinal and transverse fibres. It consists of a central 

 part or body, which ends in two columns anteriorly and two 

 crura posteriorly. 



Fasciculus mamillo-thalamicus 



Corpus callosum 



Taema thalami j j Rostrum of corpus callosum 



Base of pineal body 



Sulcus for falx 

 cerebri 



Splenium 



Median part of 



transverse fissure 



Fasciola cinerea 



Cingulum passing 

 through the isthmus 



Upper quadrigeminal body 



Posterior commissure ] 

 Fimbria 



Genu of corpus 

 callosum 



Column of fornix 

 Anterior commissur 

 Subcallosal gyrus 



'_ Optic recess 

 i Optic chiasma 

 Uncus 

 Mamillary body 



FIG. 173. Dissection showing the relations of the Fornix. 



Corpus Fornids. The body of the fornix is triangular in 

 shape. Anteriorly, where it is continuous with the columns, 

 it is narrow; posteriorly it broadens out, becomes flattened, and 

 is prolonged into the crura (Fig. 166). The posterior part of 

 the upper surface of the body of the fornix is in contact with 

 arid is adherent to the inferior surface of the posterior part 

 of the body of the corpus callosum. The remaining part of 

 the upper surface of the median portion of the fornix is 

 attached to the posterior part of the lower edge of the 

 septum pellucidum. Lateral to those attachments the upper 

 surface of the body of the fornix forms a part of the floor 

 of the lateral ventricle, on each side, and is clothed with 



