THE CEREBRUM 



427 



be kept in position. The lateral portions must be turned laterally 

 and detached completely. As that is being done, it will become 

 evident that the lower part of the splenium, which is prolonged 

 into the forceps major, is, in reality, a portion folded forwards 

 in close apposition with the under surface of the posterior end 

 of the corpus callosum. Be careful to leave the forceps major 

 in its place (Fig. 163). 



Anterior horn of lateral ventricle 



Longitudinal fissure 

 Corpus callosum 

 Cut surface of roof of lateral ventricle 



Head of caudate nucleus 

 Stria terminalis 



Chorioid plexus 

 Thalamus 



First frontal sulcus 



Central sulcus 



Chorioid plexus 

 Posterior horn of ventricle 



Cut surface of forceps major 



Fornix 

 Precentral sulcus 



Central sulcus 



Postcentral 

 sulcus 



Lateral fissure 



Corpus callosum 



Chorioid plexus 

 Calcar avis 

 ulb of posterior cornu 

 Calcarine fissure 



Longitudinal fissure 



FIG. 163. Dissection of the Lateral Ventricles of the Brain. On the right 

 side the hemisphere was cut horizontally at the level of the junction of 

 the lateral wall with the roof of the ventricle. On the left side the part 

 of the hemisphere above the corpus callosum was torn obliquely away ; 

 then the corpus callosum was cut through from above. 



The central part and the anterior horn of the ventricle are 

 now exposed ; but the cavity of the ventricle runs backwards 

 into the occipital lobe in the form of a posterior horn, and 

 downwards and forwards into the temporal lobe as the inferior 

 horn. The posterior horn should, at present, be opened on the 

 right side only. Carry the knife backwards through the medul- 

 lary substance which forms the roof of the cavity, and remove 

 a sufficient amount of the roof to give a complete view of the 

 interior of the cavity. Greater difficulty will be experienced 



