THE INTERNAL CONFIGURATION OF THE CEREBRAL HEMISPHERES 



26l 



capsule rests upon the lateral surface of the thalamus behind the lentiform 

 nucleus and contains: (1) the optic radiation from the pulvinar and lateral 

 geniculate body to the cortex in the region of the calcarine fissure, and (2) the 

 acoustic radiation from the medial geniculate body to the transverse temporal 

 gyrus. The sublenticular part of the internal capsule lies ventral to the pos- 

 terior extremity of the lenticular nucleus and contains the temporopontine tract 

 from the cortex of the temporal lobe to the nuclei pontis. 



Dissections of the Internal Capsule (Figs. 87, 88, 91, 194, 195). A large 

 part of the fibers of the internal capsule, including the corticopontine, cortico- 

 bulbar, and corticospinal tracts, are continued as a broad thick strand on the 

 ventral surface of the cerebral peduncle, with which we are already familiar 



Radiation of corpus cal- 

 losum forming roof 

 of lateral ventricles 



A nterior limb of inter 

 nal capsule (can- -^ d 

 date impression) ".^EJ 



X 



Frontal pole - 



Posterior limb of internal capsule 

 /(thalamic impression) 



/ Tapelum 



Genii internal cap- ,--^< 

 side 



Anterior commissure 



Optic tract 

 Temporal lobe - 



Basis pedunculi Optic radiation 



Fig. 195. Dissection of the human cerebral hemisphere, showing the internal capsule exposed 

 from the medial side. The caudate nucleus and thalamus have been removed. 



under the name basis pedunculi. By removing the optic tract, temporal lobe, 

 insula, and lentiform nucleus this strand can easily be traced into the internal 

 capsule where it is joined by many fibers radiating from the thalamus and 

 spreads out in a fan-shaped manner (Figs. 87, 88), forming a curved plate which 

 partially encloses the lentiform nucleus. As seen from the lateral side, the line 

 along which the fibers of the internal capsule emerge from behind the lentiform 

 nucleus forms three-fourths of an ellipse (Fig. 194). Beyond the lentiform nu- 

 cleus the diverging strands from the internal capsule, known as the corona 

 radiata, join the central white substance of the hemisphere and intersect with 

 those from the corpus callosum (Figs. 174, 238). 



An instructive view of the internal capsule may also be obtained by remov- 



