Chap. XXIir.] 



OF THE HUMAN BRAIN. 



435 



lo, pass on each side in compact columns through the 

 MeduUa, and through that continuation of it which is 

 crossed by the 

 'middle peduncles' 

 of the Cerebellum 

 (viz., the pons 

 Varolii). Beyond 

 this point, both 

 sets of fibres of 

 the one side di- 

 verge from those 

 of the other (fig. 

 154) so as 

 form what 

 known as 

 ' Cerebral 

 duncles.' These 

 parts are seen on 

 the under surface 

 of the brain, es- 

 pecially when the 

 tips of the Tem- 

 poral Lobes are 

 drawn outwards 

 or removed (fig. 

 155, re). Each 

 Peduncle soon 

 disappears within 

 the corresponding 

 Cerebral Hemi- 

 sphere, and then 

 its future course, 



or that of its constituent fibres, can only be made out by 

 the most careful dissections. It spreads out rapidly into 



Fig. 155. — On right side shows plane of fibres under- 

 lying superficial convolutions on interior aspect of Tem- 

 poral Lobe, and forming the floor of Descending Cornu. 

 The Cornu has been opened anteriorly, and fibres (s x) 

 from the apex of the lobe to the extra-ventricular Cor- 

 pus striatum are seen. On the left side of figure, the 

 dissection has been carried further, and the Optic Tract 

 has been removed, rr, Crura Cerebri, re, Crusta. rt. 

 Fibres of Tegmentum (and from Thalamus) turning 

 round anterior edge of Crusta. th, Tail of Thalamus, 

 turning round posterior edge of Crusta, forming ' Collar 

 of Crus,' and distributing fibres to Sylvian margin of 

 Temporal Lobe, th' and sx', Fibres from Thalamus and 

 extra-ventricular Corpus Striatum respectively to Oc- 

 cipital extremity of Hemisphere. The longitudin,il 

 fibres not indicated by letters belong chiefly to the sy.-i- 

 tem of the Gyrus Uncinatus. (Broadbent.) 



