284 



THE NERVOUS SYSTEM 



numerous blood vessels which assist in their nutrition. 

 The three membranes are sometimes called the cerebro- 

 spinal meninges, and the serious disease called cerebro- 

 spinal meningitis is due to inflammation of these lining 

 membranes. 



Corpus Callos 



Foramen of Monro 



\ Third Ventricle 



Pineal Body 



i Cerebrum 



Optic Chiasma 



Pituitary Body / 



Oculomotor' Nerve / 



Pons Varolii / / 



Aqueduct / / 

 Medulla Oblongat'a / 

 Fourth Ventricle 



~ Corpora 

 O/uadrigemina 



Cerebellum 



Spinal Cord 



Fig. 129. The right half of a vertical median section of the brain. 



420. The Brain (Figs. 129, 130, 131, and 134). The 

 division of the brain into five principal parts is derived 

 from the manner of the development of those parts from 

 certain primary divisions of the embryo. Those parts 

 are : (1) the cerebrum, with its two hemispheres ; (2) the 

 optic thalami; (3) the corpora quadrigemina, or optic lobes, 

 with the crura cerebri; (4) the cerebellum and pans Varolii ; 



