496 



THE BRAIN 



surface. Posterior to the septum pellucidum the under surface of the 

 median part of the corpus callosum will be found to lie upon and to be 

 connected with the upper surface of the fornix. Sever this connection 

 also. The left half of the forceps major should be preserved, so that its 

 connection with the occipital lobe may be more fully made out later. By 

 snipping off the upper edge of the septum pellucidum with the scissors, the 

 two laminae, with the interposed cleft, will be exposed. 



Cavum Septi Pellucidi (O.T. Fifth Ventricle). This is the 

 name which is applied to the median cleft between the two 

 laminae of the septum pellucidum. It varies greatly in extent, 

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



Taenia thalami 



Fasciculus thalamo-mamillaris 



Corpus callosum 

 Rostrum 



Base of pineal body 



Sulcus for falx 

 cerebri 



Splenium 



Median part of 



transverse fissure 



Fasciola cinerea 



Isthmus 



Upper quadrigeminate body ! j 

 Posterior commissure "j 

 Fimbria 



Genu 



Column of fornix 

 "Anterior commissi 

 Subcallosal gyms 



( Optic recess 

 1 Optic chiasma 

 Uncus 



Mamillary body 



FIG. 203. Dissection showing the relations of the Fornix. 



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. 



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. The upper surface of the 

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

 corpus callosum, and is adherent to it in the median plane 



