INTERNAL PAETS. 



547 



of transverse white fibres, a continuation of a series of transverse fibres 

 which underlie the corpora quaclrigemina. Its fibres, passing through 

 the thalanii, diverge in the white substance of the hemisphere. 



The corpora striata {anierior cerphraJ (janfjlia), situated in front 

 and to the outer side of the optic thahimi, are two large ovoid masses 

 of grey matter, the greater part of each of which is embedded in the 



Fig. 383. 



Fig. 333. — Dissection of the Brain from above, exposing the Lateral, — Third, and 

 Fourth Ventricles, with the surrounding parts (from Hirsclifekl and Leveill^). 4 



a, the anterior part or knee of the corpus callosum divided ; its fibres are seen spreading 

 on each side into the cerebral hemispheres ; h, anterior part of the surface of the right 

 corpus strLatum in the anterior cornu of the lateral ventricle ; h', the same on the left 

 side, in which the grey substance has been dissected so as to show the peduncular medul- 

 Jary fibres spreading through the corpus striatum into the cerebral hemisphere ; c, points 

 by a line to the taenia semicircularis ; d, surface of the thalamus opticus ; c, the anterior 

 pillars of the fornix divided ; below, they are seen descending in front of the third 

 ventricle, and between them is seen a part of the anterior commissure ; above the letter 

 is seen the fifth ventricle represented as a slit between the two lamince of the sej^tum 

 lucidum ; /, placed on the soft or middle commissure ; g, in the posterior part of the third 

 ventricle ; on either side of this letter is the white stria or peduncle of the pineal gland ; 

 immediately below the letter is the small posterior commissure and the pineal gland ; h, 

 the upper, and (', the lower of the corpora quadrigemina ; l\ superior x^eduncle of cere- 

 bellum ; and close to this the valve cf Yieussens, which is partly divided by a median 

 incision along with the middle lobe of the cerebellum, so as to o\xt\ up the fourth ven- 

 tricle ; I, the hippocampus major and corpus fimbriatum separated from the posterior 

 jnllar of the fornix and descending into the middle cornu of the lateral ventricle ; m, 

 posterior cornu of the lateral ventricle and hipiiocampus minor ; n, eminentia collateralis ; 

 o, tlie cavity of the fourth ventricle ; p, posterior surface of the medulla oblongata ; }•, 

 section of the middle lobe showing the arbor vitaj ; s, upper surface of the cerebellum 

 brought into view on the left side by the removal of the posterior extremity cf the left 

 hemisphere. 



K X 2 



