HEAD AND NECK OF THE HORSE 



189 



ventricle by the interventricular foramen (of Monro ^) (foramen inter- 

 ventriculare), a small opening immediately beneath the fornix. In 

 general, the cavity of the ventricle is not spacious, since the roof and 

 floor are usually more or less in contact with each other. Occasionally, 

 however, the dimensions of the cavity, even in a healthy specimen, may 

 be considerable. 



For descriptive purposes the ventricle is divided into a central part, 

 an anterior cornu and an inferior cornu. The central part (pars 

 centralis), extending from the interventricular foramen to the splenium 



Longitudinal fissure. 



White matter (centrum semiovale) 



Corpus callosum. 



Genu of corpus 

 callosum. 



Caudate nucleus. 



Choroid plexus. 

 Hippocampus. 



Splenium of corpus callosum. 



Cerebellum. 



Fig. 88. — Horizontal section of the cerebral hemispheres. On the right side, the corpus callosum 

 has been removed to sliow the interior of the lateral ventricle. 



of the corpus callosum, has a roof formed by the corpus callosum, and a 

 medial wall, by which it is separated from the ventricle on the opposite 

 side of the brain, consisting of the septum pellucidum. There is no 

 lateral wall, because the roof and floor meet and thus form the lateral 

 boundary. The floor of the central part of the ventricle is formed by 

 several important objects. Of these, the most anterior is a pear-shaped 

 grey eminence, the caudate nucleus (nucleus caudatus), the narrow 

 posterior end of which is continued into the inferior cornu. Along the 

 medial border of the caudate nucleus runs a vascular fringe, the 

 choroid'^ plexus (plexus chorioideus ventriculi lateralis), the appearance 

 of which might lead to the assumption that it is actually within the 

 ventricle. It is, however, excluded from the cavity by a thin, cellular 



1 Alexander Monro p-irnws, an Edinburgh anatomist, 1697-1767. 

 - Chorioideus [L.], xop'oeto^s (choriceides) [Gr.], skinlike. 



