514 rOXS VAROLII. 



well as backwards through the pons, the sixth having a tolerably straight 

 course, and the seventh curving inwards, to reach tiie nucleus which is 

 much nearer to the middle line than is the place of emergence of the 

 nerve from the side of the medulla. The nucleus consists of a column 

 of large multipolar nerve cells, and in ifc nearly all the fibres of the 

 sixth nerve, and a considerable number of those of the facial end. 

 Other fibres of the facial, however, pass above the upper extremity of 

 the nucleus and then, turning down, descend on its inner side as a 

 compact bundle (fig. 359, vii"), and opposite the lower part of the 

 nucleus radiate outwards and do^Tiwards, some to the superior olivary 

 body (so) and others to an adjacent group of nerve cells from which 

 also (higher up) the fibres of the motor root of the fifth nerve arise (vm). 



The prominence outside the vagal nucleus in the lower }jart of the 

 ventricle marks the position of the inner nucleus of the auditor// nerve 

 (fig. 355). It is triangular on section, and consists of oval and stellate 

 nerve cells, smaller than those of the facial nucleus, and imbedded in a 

 granular matrix. It is closely connected below with the nucleus of the 

 glossopharyngeal nerve, and above, with that of the fifth nerve. The 

 outer nucleus, a little higher up, is placed to the outer side of the inner 

 nucleus, and consists of the grey network of cells and fibres into which 

 the restiform and post-pyramidal nuclei have become transformed. 

 (Lockhart Clarke.) The auditory nerve divides into two nearly equal 

 parts ; the posterior division curves round the restiform body, and 

 arises chiefly from the inner nucleus : the anterior division passes 

 through the substance of the inferior peduncle of the cerebellum, and 

 arises from both nuclei ; some fibres of the anterior division pass with 

 the restiform body directly to the cerebellum, where they have been 

 traced to the superior vermiform process. Both portions of the auditory 

 nerve contain many nerve cells ; in the inferior or outer portion they 

 constitute a pyriform swelling at the anterior edge of the restiform 

 body. 



The sensory 2^ortion of tJis fifth nerve arises from a collection of 

 grey substance beneath the outer part of the floor of the fourth ven- 

 tricle in its middle third. It is derived chiefly from the continuation 

 upwards of the grey tubercle of Rolando, which constitutes a grey 

 net- work outside the facial nerve (fig. 359, vs). The cells are small 

 and arranged in clusters separated by the fasciculi of origin of the 

 nerve. In front of the nucleus a bimdle of descending fibres passes 

 down, mingled with much grey matter, to the lower part of the 

 medulla oblongata. As the fibres of the fifth pass to the nucleus, they 

 are intimately connected with the fibres of the anterior division of the 

 auditory ne]-ve. The fibres of the motor root of the fifth, have been 

 traced by Lockhart Clarke to a collection of cells close to the outer 

 angle of "the fourth ventricle, on the inner side of the trunk of the fifth 

 nerve. The prolongation downwards of this nucleus (fig. 359, Vm), 

 is situated near the superior olivary body, and with it some fibres of the 

 facial are also connected. 



The superior olivary body (fig. 359, s o) is a collection of small nerve 

 cells, which lies above the outer part of the trapezium. In man it is 

 very much smaller than the inferior olivary body, to which it does not 

 present much resemblance. In some animals, however, it is larger, and 

 presents a distinctly sinuous outline. From it some of the fibres of the 

 trapezium arise. 



