INTERLACEMENT OF THE CEREBELLAR PEDUNCLES. 467 



fourth ventricle (fig. 252, A), there becomes associated with 

 the portion of the posterior division of the pons, which forms 

 the tegmental origin of the antero-lateral columns of the spinal 

 cord (already described), and the crus cerebri, in its further 

 course, the following parts, viz., (1) the transverse section of 

 the portion of the fillet proceeding from the testes, the " pes of 

 the fillet" (figs. 252, and 253, 8) ; (2) the transverse section of 

 the ascending root of the fifth (figs. 253, Q ; 254, 257, 258, 8) ; 

 and (3) the just-described inferior peduncle of the cerebellum. 



The tegmental origin of the antero-lateral column permits 

 distinct areas to be distinguished in two different directions, 

 first those placed one behind the other, which proceeding from 

 the grey floor are (1) the posterior longitudinal fasciculi ; (2) 

 the (middle) motor area ; (3) the fillet (Schleifenschichte, Rei- 

 chert) ; and secondly, those in lateral juxtaposition which are (1) 

 the region of the anterior column, forming the territory adja- 

 cent to the raphe that is bounded laterally in the pons by the 

 roots of the nervus abducens, and in the oblongata by the roots 

 of the hypoglossus ; and (2) the region of the lateral column 

 extending from this boundary as far as to the ascending roots 

 of the fifth, in which also the pes of the fillet is enclosed (Fuss 

 der Schleife, Stilling). 



The posterior longitudinal column, which in transparent 

 longitudinal sections obviously proceeds from the cerebral pe- 

 duncle, runs continuously through the medulla oblongata, and 

 is prolonged into the posterior fasciculi of the anterior column 

 of the spinal cord ; like the fillet, it owes its compact appear- 

 ance and high relief to the large calibre even in the uppermost 

 part of the crus cerebri of its medullary fibres. The remaining 

 area of the continuation of the tegmentum first obtains this 

 compact appearance at a lower point. According to Deiters, the 

 alteration of calibre always first occurs subsequent to or below 

 the point where nerve cells are primarily introduced into the 

 course of the fibres. 



The conversion into stronger fibres occurs in such a manner 

 that in the planes of origin of the nervus facialis the portions 

 of the anterior columns adjoining the posterior longitudinal 

 fasciculi and the fillet become progressively more compact; and 

 in the uppermost transverse planes of the medulla oblongata 



HH2 



