THE DIE]VCEPHALON 



505 



optic thalami of the two hemispheres are united with each other 

 by the posterior commissure, which bridges across the third ven- 

 tricle. 



The caudate nucleus lies dorso-lateralward from the optic thal- 

 amus, which latter body it partially encircles. It projects into 

 the wall of the lateral ventricle, and is separated from the optic 

 thalamus by a thin band of white matter. 



The optic thalamus and caudate nucleus, on the mesial side, 

 are separated from the more laterally situated lenticular nucleus 

 by a broad band of white matter, the cerebral continuation of the 

 pyramids, fillet, and other long fibre tracts of the mesencephalon. 



FIG. 392. A SECTION OF THE HUMAN BRAIN STEM AT THE MID-LEVEL OF THE OPTIC 



THALAMUS. 



Cfe, external capsule; Cex, capsula extrema; 7*', internal capsule; <?, claustrum ; 

 Coa, anterior commissure; Coao, olfactory bundle to the anterior commissure; Fo, 

 fornix ; fol, olfactory bundle of Zuckerkandl; glp, globus pallidus; Gorb, orbital con- 

 volutions of the cortex ; 7, island of Keil ; Lmm, lateral medullary layer of the thalamus ; 

 Nc, caudate nucleus ; Ndm, dorsal nucleus of the thalamus ; Nl, lateral nucleus of same ; 

 Nm, mesial nucleus of same ; Pu, putamen ; rcc, fronto-occipital bundle ; Ssc, stratum 

 subcallosum ; St, stria cornea ; 7Y, teenia thalami ; Fa, bundle of Vicq d'Azyr ; F//7, 

 third ventricle. Weigert's stain, x 1|. (After Marburg.) 





