396 



THE NERVOUS SYSTEM 



The lateral ventricles in man are frequently named the 

 first and second ventricles. 



Extending from one side to the other of the third ven- 

 tricle is a solid cord called the median commissure. The 

 sides of the cavity are formed by the optic lobes, or thalami, 



foramen of Monro 



n 7j„.,™ \ Third Ventricle 



Corpus Caaoswm \ ,^ pineal Body 



\ fornix \ \ \ „^, 



'~~Corpora 

 Quadrigemina 



■Cerebellum 



Optic Chiasma 



Tiiuttary Body i 



Oculomotor Nerve / / 



Pons Varolii / i 

 Aqueduct / 

 Medulla Oblongata / 

 Fourth Ventricle 



•Spinal Cord 



Fig. 184 — Vertical section of brain. 



and its floor is formed by the crura cerebri, or stalks, of the 

 cerebral hemispheres. We have already noted that these 

 stalks are the forward extensions of the medulla. At the 

 rear of the third ventricle is a passage called the iter, or 

 aqueduct, leading to the fourth ventricle, a small cavity in 

 the hindbrain. The top and sides of this iter are formed 



