47 



THE BRAIN 



nucleus, to the parietal lobe and the posterior part of the 

 frontal lobe. The temporal peduncle or ventral stalk is 

 formed by fibres which spring from the cells of the medial 

 and lateral nuclei. They issue from the lower surface of the 

 anterior part of the thalamus and pass, below the lentiform 

 nucleus, to the temporal lobe and the insula. The occipital 

 peduncle springs from the lateral side of the posterior end of 

 the thalamus, in the region of the pulvinar, and its fibres 

 form the optic radiations. They pass through the posterior 



White matter of frontal lobe 

 Groove for lenticulo-striate artery 

 Coron-t radiata 



Fibres of optic -%-* 



radiations 

 Fibres of acoustic - 



ra tiations 

 Lateral geniculate " 



body 

 Medial geniculate 



body" 



Lentiform nua 

 Roof of inferior horn of / 

 lateral ventricle ' 

 Pedunculus cerebri 

 Anterior commissure / 

 Mamillary bodv 



Orbital surface of frontal lobe 



[factory tract 

 I Optic nerve 

 Anterior perforated substance 



Optic tract Tuber cinereum 



FIG. 189. Dissection of the right Lentiform Nucleus and the right Corona 

 Radiata from the lateral side. 



or retro-lentiform part of the internal capsule and are dis- 

 tributed to the cortex of the occipital lobe, especially in the 

 region of the calcarine fissure (Figs. 182, 191). 



Dissection. Take the lower part of the remains of the right 

 hemisphere and from its lateral side tear away the grey and 

 white matter of the insula, then the claustrum, and, finally, the 

 external capsule, to expose the lateral surface of the lentiform 

 nucleus. As this is being done note the fibres which pass through 

 the region of the limen insulae and connect together the frontal 

 and the temporal lobes ; they constitute the fasciculus uncinatus. 

 Note also that the white layer which lies below the lentiform 

 nucleus contains (i) In its posterior part, the fibres of the 

 acoustic radiations ; (2) In its anterior part the fibres of the 

 temporal peduncle of the thalamus ; and in addition the fibres of 



