352 



ANATOMY IN A NUTSHELL. 



choroid plexus of the third ventricle and each, side the choroid plexus of the 

 lateral ventricles are formed. 



The optic thalami are mostly gray matter but are white exterally and are 

 situated above the tegmentum of the cms. The inner surface of each forms the 

 lateral bounary of the third ventricle and the upper suiface forms part of the 

 floor of the lateral ventricle. 



The internal capsule (fibres of the crusta or pes) separate the outer sur- 

 face of each optic thalamus from the lenticular nucleus. Each optic thalamus 

 has four surfaces. (1) superior or dorsal (2) inferior or ventral, (3) internal or 

 mesial, and (4) external or lateral. The taenia semicircularis separates the 



PLATE CLXXI1. 



POSTERIOR CORNU 



FORAMEN OF MONRO 



ANTERIOR CORNU 



A Cast of the Ventricles of the Brain. 



superior surface from the caudate nucleus. This surface is divided by the 

 sulcus choroidens into mesial and lateral portions. The lateral portion of this 

 depression is in the floor of the lateral ventricle. Anteriorly it grows into a 

 prominence, the anterior tubercle. The superior surface is separated from the 

 mesial surface by the peduncles of the pineal gland. The posterior surface 

 divides into a large prominence, the pulvinar. The trigonum habenulae is a 

 depressed area of gray matter between the pulvinar and the beginning of the 

 peduncles of the pineal gland. The ganglia of habenulae is anterior to the tri- 

 gonum habenulae. 



The internal and external geniculate bodies are elevations of gray matter 

 on the posterior and inferior surface of the pulvinar. The internal geniculate 

 body is situated on the inferior and inner side of the pulvinar, between the 

 brachia of the corpora quadrigemina. It is covered" with a layer of white fibers. 

 The external geniculate body is below and external to the internal geniculate. 



