358 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



With the infero-medial strand (IM.) issue the third and sixth 

 nerves, the former being merely loosely attached to its medial aspect, 

 the latter within its sheath along the ventral edge. With the 

 supero-lateral strand issues the ramus buccalis, but in a separate 

 sheath. 



Of the branches mentioned, the R. buccalis, oticus, and ophthal- 

 micus super ficialis, can be traced directly to the roots from the tuber - 

 culum acusticum ; their fibres are for the most part extremely broad, 

 similar to those which form the auditory nerve, but some fine fibres 

 are received from the dorsal geniculated root. To the latter are 

 traceable for the most part the R. lateralis and ophthalmicus, as 

 well as the infero-medial strand, while the supero-lateral strand is 

 formed in great part by the broad motor fibres of the ascending and 

 transverse root. (N. V., asc. et trans.). .The two principal roots thus 

 assume a different relative position in the complex to what they 

 have on emergence, immediately after which, indeed, they cross. It 

 is to be understood that neither the infero-medial nor supero-lateral 

 strands are exclusively formed of fibres coining from one of the 

 principal roots, but only chiefly so. The facialis, again, as it emerges 

 from its foramen, although it contains all the broad fibres (13 fi) 

 which emerge as the motor root of the seventh, has also acquired 

 fibres from the tuberculum acusticum (10 ;±) and others of narrower 

 diameter from the ganglionic complex, so that, although chiefly sup- 

 plying the muscles of the palatine arches, the operculum and the 

 hy oidean apparatus, it serves also as a path for fibres of different 

 destiny. 



The auditory nerve (N~. VIII., Figs. 14, 15 and 16, PL I.) leaves 

 the tuberculum acusticum on a level with the motor root of the 

 facial, and just behind that. Above it those fibres from the tuber- 

 culum acusticum which are destined for the vagus group, form a 

 white band coursing backwards immediately under the crest of the 

 tuberculum. (Fig. 3, PI. V.). Almost immediately after its origin 

 rthe auditory nerve divides into the shell-like ramus anterior, and the 

 more cord-like ramus posterior, and indeed the cords of the latter, 

 and the division between the anterior and posterior branches, may be 

 carried very nearly up to the point of emergence from the brain. 

 The fibres of the ramus posterior would seem to emerge somewhat 

 .higher than those of the ramus anterior. (Fig. 15, PI. I.) 



