1.04 THE CEREBRUM. 



In the extreme upper part of the capsule the region of the 

 parietal stalk contains nearly all of the common sensory fibers. 

 The recent investigations of Paul Flechsig show that it is built 

 up of six bundles of fibers, two of which (alpha and gamma) 

 proceed from the globus pallidus and four from the thalamus. 

 According to Flechsig there are corticifugal fibers intermingled 

 with the corticipetal in all of the sensory tracts of the capsule. 

 The common sensory fibers of the internal capsule constitute 

 the cortical fillet. 



Special Sense Fibers (Figs. 32, 33 and 70). At the junction 

 of the superior and inferior laminae of the internal capsule are 

 the special sense fibers. The optic radiation (radiatio occipito- 

 thalamica) and acustic radiation (radiatio temporo-thalamica] 

 occupy the retro-lentiform part of the internal capsule. The 

 former extends through it from the lateral geniculate body and 

 thalamus to the cuneus and lingual gyrus; the latter rises in the 

 medial geniculate body and ends in the superior and transverse 

 temporal gyri. The optic and acustic radiations both contain 

 corticifugal fibers which rise in the visual and auditory cortex, 

 respectively, and run through the capsule to the lateral and medial 

 geniculate bodies and perhaps on to lower nuclei. 



Many fibers of the internal capsule give off branches (collaterals) 

 which pass through the corpus callosum to the opposite hemisphere ; 

 other fibers may be traced entire through the same course to the 

 cortical cells of the opposite side. A bundle of thalamic fibers 

 has been so traced. 



The superior lamina of the internal capsule, proceeding outward 

 and upward into the hemisphere, intermingles with the corpus 

 callosum and enters into the corona radiata. Together with 

 the caudate nucleus, thalamus and stria terminalis (taenia semi- 

 circularis), which lie on its medial surface, it forms the entire 

 lateral boundary of the general cavity of the fore-brain. It thus 

 determines the lateral part of the ulterior surface. 



Corpus Callosum (Figs. 29, 30, 34 and 42). The entire roof 

 of the fore-brain cavity, representing the base of the wedge, is 

 formed by the corpus callosum. A part of the anterior boundary 

 is also formed by it. The corpus callosum is a thick sheet of 



