4 38 



THE BRAIN 



the septum pellucidum a thin median partition between 

 the lateral ventricles of opposite sides. The sloping floor 

 presents a marked elevation or bulging, viz., the smooth 

 rounded and enlarged anterior extremity of the pear-shaped 

 caudate nucleus. 



Pars Centralis Ventriculi Lateralis. The central part 

 of the ventricle is roofed likewise by the corpus callosum. 

 On the medial side it is bounded by the posterior part of the 

 septum pellucidum, and more posteriorly by the attachment 

 of the fornix to the under surface of the corpus callosum. 



Corpus callosum Chorioid plexus 

 Lateral ventricle I I Striae on corpus callosum 

 Caudate nucleus 



Fronto-occipital fasciculus 



i Longitudinal fissure 

 ', ! Septum pellucidum 



Vena terminals | 3rd ven tricle 



Subthalamic body | Chorioid plexus 



Thalamus Red nucleus 



FIG. 198. Frontal Section showing immediate relations of Lateral and 

 Third Ventricles. (Part of Fig. 217 enlarged.) 



On the lateral side it is closed, as in the case of the anterior 

 horn, by the meeting of the roof and the floor of the cavity. 



On the floor a number of important objects may be 

 recognised. Latero-medially, and, at the same time, to some 

 extent antero-posteriorly, these are ( i ) the caudate nucleus ; 



(2) a groove extending obliquely, postero-laterally, between 

 the caudate nucleus and the thalamus, in which are placed 

 the terminal vein (O.T. vein of corpus striatum) and a white 

 band called the stria terminalis (O.T. taenia semicircularis) ; 



(3) a portion of the upper surface of the thalamus; (4) 

 the chorioid plexus ; (5) the thin sharp lateral edge of the 

 fornix. 



