502 



HANDBOOK OF PHYSIOLOGY. 



F. The Cerebrum. 



Relation to other part*. The relation of the cerebrum to the other 

 parts of the central nervous system will be understood on reference to 

 Figs. 343, 344. 



It is composed of two so-called halves or hemispheres, and is placed in 

 connection with the Pons and Medulla oblongata by its two Crura or pe- 

 duncles (III. Fig. 341): it is connected with the cerebellum by the pro- 

 cesses called superior crura of the cerebellum, or processes a cerebeUo ad 

 testes, and by a layer of gray matter, called the valve of Vieussens. which 



FIG, 342. Dissection of brain, from above, exposing the lateral fourth and fifth ventricles with 

 the surrounding parts. %. a, anterior part, orgenuot corpus callosum; 6, corpus striatum; &', 

 the corpus striatum of left side, dissected so as to expose its gray substance; c, points by a line to 

 thetaeniasemicircularis; d, optic thalamus; e, anterior pillars of fornix divided; below they are 

 seen descending in front of the third ventricle and between them is seen part of the anterior com- 

 missure ; in front of the letter e is seen the slit-like fifth ventricle, between the two laminae of the 

 septum lucidum; /, soft or middle commissure; g is placed in the posterior part of the third ven- 

 tricle; immediately behind the latter are the posterior commissure (just visible) and the pineal gland, 

 the two crura of which extend forwards along the inner and upper margins of the^ optic thalami; 

 ftand i. the corpora quadrigemina; A;, superior crus of cerebellum, close to k is the valve of Vieus- 

 sens, which has been divided so as to expose the fourth ventricle; I, hippocampus major and cor- 

 pus fimbriatum, or ta3nia hippocampi; m, hippocampus minor; n, eminentia collateralis; o, fourth 

 ventricle; p, posterior surface of medulla oblongata; r, section of cerebellum; s, upper part of left 

 hemisphere of cerebellum exposed by the removal of part of the posterior cerebral lobe,, 

 (Hirschfeld and Leveille.) 



lies between these processes, and extends from the inferior vermiform 

 process of the cerebellum to the corpora quadrigemina of the cerebrum. 

 These parts, which thus connect the cerebrum with the other principal 

 divisions of the cerebro-spinal system, may, therefore, be regarded as the 



