48 GRAY SUBSTANCE OF THE TRAPEZIUM, 



iiig inwards to the anterior portion of the nucleus, accompanied by numerous small 

 bundles which enter the loose network constituting the outer portion of the nucleus, 

 while another division diverges, and winding around the outer edge of the restiform 

 body, enters the posterior portion of the nucleus in company with the posterior 

 roots. The connection between the auditory nucleus and the cereheUum is now 

 very conspicuous (Plate IV, Fig. 13, Plate XVI, Figs. 12'' and 44); numerous 

 bundles Avhich proceed from the cerebellum pass down through the nucleus and 

 enter the medulla, radiating in aU directions in the anterior and antero-lateral net- 

 work, and a portion of these fibres are also continuous with cell-processes in the 

 postero-lateral portion of the nucleus. 



The connection between the ujijier olivary bodies and the facial nucleus is very 

 evident in the upper part of the trapezium, and will be referred to subsequently. 

 The groups of large cells near the facial, figured by Schroder van der Kolk (MeduUa 

 Oblongata, Fig. 20, o), and another group found near the outer edge of the caput, 

 are evidently of the same nature as the upper olivary bodies. 



(8.) In the upper part of the course of the facial, the nucleus has entirely dis- 

 appeared (Plate IV, Figs. 14, 15, 16 and Plate XIV, Fig. 16"), and the roots are 

 seen in two or three very large bundles, whose entire course can be traced inwards 

 to the longitudinal columns on each side of the middle line, called by Stilling the 

 " constant roots of the trifacial." These columns are inclosed by the root-bundle, a 

 portion of the fibres of Avhich seem to abruptly terminate here ; the remainder can, 

 however, be traced onward to the raphe where they are seen to decussate with their 

 fellows from the opposite side. Throughout their entire course the facial roots are 

 crossed at various points by fibres radiating from the auditory nucleus, many of 

 which proceed from the cerebellum either directly or after passing through cells. 



(9.) The longitudinal columns on each side the raphe near, the floor of the ventri- 

 cle (Fig. 12", y. Fig. 44), referred to above, have been described by StiUing as the 

 ^"■constant roots of the trifacial" and by Schroder van der Kolk as '■'■roots of the audi- 

 tory." I have not been able to discover any connection between these columns and the 

 trifacial or auditory roots, and in the chapter on the facial nerve, I have endeavored 

 to show, that a portion of the facial roots probably descend in these columns to the 

 underlying nu.cleus. With the exception that they are intermingled with descend- 

 ing facial roots, these columns seem to be simply bundles belonging to the general 

 system of the longitiidinal postero-lateral columns, from Avhich they are separated 

 to some extent by the facial roots on their way to the raphe, but to a still greater 

 extent, especially in front, by the curving fibres which sweep out from the auditory 

 nucleus. 



(10.) In sections from the upper part of the trapezium the chief changes notice- 

 able consist in the gradual disappearance of the nerve-roots we have been consider- 

 ing, as well as of the upper olivary bodies (Plate XIV, Fig. 16"). The external 

 arciform fibres constituting the border of the trapezium have increased very much in 

 number as we approach the pons Varolii. The upper olivary bodies (0') are very 

 much reduced in size, appearing now as simple rounded masses, containing a few 

 small cells, almost hidden by the wavy bundles of arciform fibres. 



The roots of the facial (Fig. 16, 16", VII) are reduced to a few small bundles, 



