THE CEREBRUM 



485 



through the lateral part of the temporal lobe, towards the temporal pole, 

 following the, course of the cavity. This corresponds very nearly with the 

 course of the superior temporal sulcus. The lateral wall of the inferior 

 horn is thus incised, and a sufficient amount of the lateral part of the 

 temporal lobe must be removed to give a view of the cavity. In doing this, 

 the temporal operculum will be taken away, but the surface of the insula 

 should be preserved from injury. 



Lateral Ventricle. The dissector will now perceive that 

 each cerebral hemisphere is hollow. The cavity in the interior 

 is called the lateral ventricle. It is lined with a thin dark- 



Central part of lateral ventricle 



Inferior pineal recess 



Superior 

 pineal recess 

 Aqua:ductus 

 cerebri 



"" Interventricular 



foramen 

 Third ventricle 

 Optic recess 



Infundibular recess 



Lateral recess 



FIG. 195. Cast of the Ventricles of the Brain (from Retzius). 



coloured layer of epithelium, which is termed the ependyma. In 

 certain places its walls are in apposition with each other, but 

 in other localities spaces of varying capacity, and containing 

 cerebro-spinal fluid, are left between the bounding walls. The 

 lateral ventricle communicates with the third ventricle of the 

 brain by means of a small foramen, which is termed the 

 interventricular foramen (O.T. foramen of Monro). This 

 aperture, which is just large enough to admit a crow-quill, 

 lies at the anterior end of the thalamus, and posterior to 

 the column of the fornix (O.T. anterior pillar). 



The shape of the lateral ventricle is very irregular, and 

 can be best understood by the study of a plaster cast of 

 its interior (Fig. 195). It is composed of a central part 

 (O.T. body) and three horns, viz., an anterior, a posterior, 



