THE CEREBELLUM. 



14à\ 



The fibres of the second lawyer Fig. 102. 



course, for the most part, in an almost 

 vertical plane ; they connect the cere^ 

 bell am with the optic lobes i^procesms 

 cerebelll ad corpora lAgemina^ and with 

 other parts of the brain. 



The fibres of the fourth layer re- 

 ceive numerous long" processes from 

 the larg-e cells of Purkinje; they form 

 a large commissural system, which can 

 be followed ventrally on each side into 

 the pars cowmissvralis. A part of the 

 fibres ends here in the g'rey matter, a 

 second portion enters the auditoiy area 

 and forms a descending auditory root, 

 a third part joins the lateral columns 

 (in the medulla oblongata), and more an- 

 teriorly some join the ventral columns. 

 The descending fibres from the cere- 

 bellum, together with the fibrae arcit- 

 atae found in the ventral cohimns, 

 indicate the presence of a pons Va- 

 rolii. The fibres of this ventral com- 

 missure decussate only on its dorsal 

 surface (Koppen). 



The Falvnla cerebelli contains a few w, optiu tract. 

 medullated fibres and the roots of the J"f T"»^«r cinereum. 



J 11 XI 1} l^ }'' ,> root of the olfactory nerve. 



trochlear nerves; these pass from the /12nd) 



'medulla oblongata into the valmda m oraîo-mÔtor nerve, 



cerebelli, cross in the median line, and [l\ i';"«h'ear nerve. 



' ^ \ I Abducens nerve. 



then proceed forwards as the troch- >'. ''A ym Trigeminal, facial, and 



, auditory nerves. 



lear nerves. /.Y, A', XI Glossopharyngeal, imeimio- 



gastric, and iuxessory nerves. 



The pigment in the jij«;v? commissu- 

 ralis is arranged in a curved line similar to that found in the 'me- 

 dulla oblongata, hut the line is shortened at either extremity, and 

 consequently does not extend into the ceretjellum. 



c. The optic lobes and Crura verehri. (Corpora geminata and 

 Pars pjeduncularls, Reissner ; Lobus ojjticus, Stieda ; Vierhiig-el, 

 Tiedemann ; Vierhiigel (Zweihiigel) and Pedunculi cerebri, Schiess ; 

 Mesencephalon, H uxley . ) 



\entral view of brain of liana 

 ngcukida. 

 Cho Optic chiasrua. 

 lie Cerebral hemispheres. 

 //// Pitnitary body. 

 L.iil Olfactory lobe, 

 i.oA ()rigin of olfactory nerve from 



tlie cerebral hemisphere. 

 LI Lamina terminalis. 

 Mo Medulla oblongata. 



