C. WINKLER. THE CENTRAL COURSE 



fibres. Between the endings of the rootfibres and the origin of new 

 secundary systems however there must be intercalated small cells. 



n. The nucleus dorsalis nervi octavi. 



Before returning to the different root-fibres, which I left in the 

 radiation at the dorsal border of the area ovalis, it now will be 

 necessary to describe two very important parts of the auditory 

 system, viz: the nucleus dorsalis nervi octavi and the portio interna 

 of the corpus restiforme. 



Else the nuclei situated therein, and the fibre-systems ending 

 in them or passing through them , may not easily be understood. 



Now the dorsal nucleus is the most extensive of the auditory 

 nuclei. In frontal sections it begins already at a level with the 

 clear nucleus of the X th nerves and ends nearly at the entrance of 

 the pedunculus superior cerebelli (see for instance Plate VIII fig. 

 15 N. 4 11) in the metencephalon. 



At its largest extensity it. takes nearly the whole bottom of the 

 4 th ventricle, between the genu of the VII th nerve and the portio 

 interna corporis rectiforme. 



From the tuberculum acusticum, its lateral part is not always 

 distinctly separated. If it is separated from it, the radiation of the 

 dorsal systema at the dorsal border of the oval area confines laterally 

 the nucleus. The large number of transverse fibres originating from 

 this radiation and bending in medio-ventral direction , as transverse 

 dorsal fibres , distinctly separate the nucleus from the portio interna. 



In this way, laterally limited by the descending VIII th root, 

 ventrally by the formatio gelatinosa of the spinal V th root, by the 

 formatio reticularis and the genu of the VII th , the dorsal nucleus 

 obtains its triangular shape, its basis situated at the bottom of the 

 4 th ventricle its apex resting upon the descendent root of the radix 

 ventralis (f. i. Plate III, fig. 135). 



In the ventricle it is making three pro-eminencies. The most 

 medial one, next to the raphe is in reality caused by the knee 

 of the VII th nerve. More laterally, the larger vault is made by the 

 principal mass of cells of the dorsal nucleus, and a smaller, most 

 laterally situated, is the expression of its lateral mass of cells (see 

 Plate VII fig. 7. F and G). Now if the limits of the dorsal nucleus 

 are not precisely defined , especially its relations towards the portio 

 interna of the C. R. , it afterwards may offer difficulties to fix the 

 relations of the auditory root-fibres to it and to the nucleus of 

 BECHTEREVV. And in. order to avoid the confusion which very often 



