296 HUMAN ANATOMY. 



Fasciculus longitudinales inferior; 



Olfactory tracts; 



Crura cerebri; 



Peduncles of pineal gland; 



Processus a cerebello ad testes. 



VENTRICLES OF THE BRAIN. 



The interior of the brain contains five distinct cavities, 

 named the ventricles of the brain, situated as follows : Two lat- 

 eral ventricles in the upper part, within the substance of the 

 hemispheres, the third ventricle between the optic thalami at the 

 base of the brain, the fourth ventricle between the medulla 

 oblongata and the cerebellum, and the fifth ventricle within the 

 septum lucidum between the two lateral ventricles. 



The ventricles intercommunicate the two lateral ventricles 

 with the third by means of the foramen of Monro, the third 

 with the fourth ventricle by means of the iter a tertio ad quartum 

 ventriculum, and, in the foetus, with the fifth, and through the 

 infundibulum with the cavity of the pituitary body. 



THE LATERAL VENTRICLES are bounded as follows: 



The roof, the corpus callosum; the floor is formed by the follow- 

 ing parts from before backward: corpus striatum, teenia semicircu- 

 laris, optic thalamus, choroid plexus, corpus fimbriatum and fornix ; 

 internally, by the septum lucidum; externally, in front and behind by 

 the brain-substance. Each lateral ventricle presents three cornua the 

 anterior cornu, posterior cornu, or digital cavity, and the middle cornu. 



The anterior cornu curves outward and forward over the 

 corpus striatum and into the anterior lobe. 



The middle cornu passes into the middle lobe, ascending to 

 the transverse fissure at the base of the brain. Its course is back- 

 ward, outward, downward, forward, and inward (B., 0., D., 



P., i.). 



The posterior cornu runs backward into the posterior lobe, 

 its course being backward, outward, and inward (B., 0., I.). 



Parts of Lateral Ventricle Corpus Callosum. Described 

 above. 



Septum Lucidum. Forms the internal boundary of the 

 lateral ventricle. It consists of two layers of white and gray 

 matter, and is attached above to the under surface of the corpus 

 callosum, below to the fornix, and anteriorly to the prolongation 

 of the corpus callosum. 



Between the laminae forming the septum is a narrow interval 

 the fifth ventricle. 



The Corpus Striatum. Situated in the lateral ventricle, its 

 broad end directed forward into the fore part of the body and 



