1088 SENSATIONS OF HEARING. [BOOK in. 



different footing from the two preceding special senses, since the 

 nerves concerned belong to the category of ordinary cranial 

 nerves, and we lack, in reference to them, the anatomical leading 

 which is offered to us in the case of the optic and olfactory nerves. 

 We shall see in dealing with the senses that the fifth nerve 

 and the glossopharyngeal nerve have been considered as nerves 

 of taste, but that the matter is one subject to controversy ; the 

 gustatory function of the fifth is attributed to the peculiar 

 chorda tympani nerve, and other questions have been raised. 

 Whatever view we take, however, the nerves of taste are ordinary 

 cranial nerves, and we have no anatomical guidance as to the 

 fibres of either of the above two nerves making special connec- 

 tions Avith any part of the cortex. Though sensations of taste 

 enter largely into the life of animals, and indeed of man himself, 

 we have no satisfactory indications which will enable us to 

 connect this special sense with any part of the cortex ; the 

 view indeed has been put forward that some part of the cortex 

 in the lower portion of the temporal lobe, not far from the centre 

 for smell, serves as a centre for taste ; but the arguments in 

 favour of this view are not, as yet at least, convincing. 



Sensations of Hearing. 



677. The cochlear division of the eighth or auditory nerve 

 may be assumed to be a nerve of the special sense of hearing, and 

 of that alone ; the vestibular division serves, as we have seen, for 

 other functions than those of hearing, 642, but as we shall urge in 

 dealing with the senses is not to be regarded as wholly useless for 

 the purposes of that sense. The cochlear division we have traced, 

 618, into the bulb, and the vestibular division into the lateral 

 auditory nucleus (which perhaps may be regarded as a continua- 

 tion or segmental repetition forwards of the cuneate nucleus or of 

 part of that nucleus), and into the cerebellum, the cerebellar 

 continuation being probably the part of the nerve which serves for 

 coordinating functions. The connections of the auditory nerve 

 with the cerebral hemisphere belong to the same category as 

 those of other afferent cranial, and we may add spinal nerves ; 

 we have no very clear anatomical guide towards any particular 

 part of the cortex. 



When we turn to the empirical results furnished by experi- 

 ment and clinical observations, we find that these, though even 

 less definite and less accordant than in the case of the senses 

 of sight and smell, point to part of the first or superior temporal 

 (temporo-sphenoidal) convolution (Figs. 126, 129, 131) lying rn 

 the temporal lobe just ventral to the Sylvian fissure, as being 

 specially concerned in hearing in some such way as the occipital 

 lobe is concerned in vision. 



