XI 



THE BRAIN 



603 



of the pons are seen in section at P, while the longitudinal 

 fibres of the bulb run forward above the pons tf) emerge 

 in front as one of the (right) crura cerebri. Antericnly 

 this crus disappears out of the section since it diverges bo 

 the right (see Fig. 160) from the median line of the brain 



Fio. 101.— View of the Right Half of a Human Brain as shown by 



A LOS'CITUDINAL SECTION I.V THE MEDIAN LiNE THROUGH THE LONGI- 

 TUDINAL Fissure. (Aftek Sherringtos. ) 

 Sp.c. spinal cord; B, bulb; F, pons; Cli, ovs cerebri ; M, corpus al- 

 bicans: CO, cerebellum; r, central canal of spinal cord opening into 4, 

 the fourth ventricle ; V.l', valve of Vieussens ; QP, QA, corpora quadri- 

 gemina, beneath which is the aijueduct or Si/lvitis leading from the 

 fourth ventricle into 3, the cavity of tlie third ventricle; P, pmeal 

 gland ; F, fornix or roof of third ventricle ; OT, optic thalamus : 

 H, pit'uitarv body; OP, optic nerve cut across at the optic decussation 

 (see Figs. 160 and 167); 6i. apart of the septum htcidvm, of which the 

 remainder has been cut away to reveal NC, I V, the cavity of the lateral 

 ventricle ; this cumniunicates with the third ventricle by means of the 

 foramtn of Monro, whose position is marked by a small x at the front 

 end of this thirl ventricle ; r.c, c.c, c.c, corpus calldsum, above which is the 

 mesial surface of the right cerebral hemisphere. 



to enter the corresponding cerebral hemisphere. The 

 cerebellum Cb, is seen in section ovevhnnglng the bulb, and 

 between it and the bulb is the cavity, shided and marked 

 with a 4, to which we have i)reviously alluded as the/o»r/7i 

 ventricle. The central canal c.c. of the spinal cord is shown 



