THE GLOSSO-PHARYNGEAL NERVE. 437 



cites, through the medium of the medulla obloDgata, -the ac- 

 tions of the muscles of deglutition. It is the chief centripetal 

 nerve engaged in these actions ; yet not the only one, for, as 

 Dr. John Reid has shown, the acts are scarcely disturbed or 

 retarded when both the glosso-pharyngeal nerves are divided. 



But besides being thus a nerve of common sensation in the 

 parts which it supplies, and a centripetal nerve through which 

 impressions are conveyed to be reflected to the adjacent muscles, 

 the glosso-pharyngeal is also a nerve of special sensation ; being 

 the gustatory nerve, or nerve of taste, in all the parts of the 

 tongue to which it is distributed. After many discussions, the 

 question, which is the nerve of taste ? the lingual branch of 

 the fifth, or the glosso-pharyngeal ? may be most probably 

 answered by stating that they are both nerves of this special 

 function. For very numerous experiments and cases have 

 shown that when the trunk of the fifth nerve or its lingual 

 branch is paralyzed or divided, the sense of taste is completely 

 lost in the superior surface of the anterior and lateral parts of 

 the tongue. The loss is instantaneous after division of the 

 nerve ; and, therefore, cannot be ascribed to the defective nu- 

 trition of the part, though to this, perhaps, may be ascribed 

 the more complete and general loss of the sense of taste when 

 the whole of the fifth nerve has been paralyzed. 



But, on the other hand, while the loss of taste in the part of 

 the tongue to which the lingual branch of the fifth nerve is 

 distributed proves that to be a gustatory nerve, the fact that 

 the sense of taste is at the same time retained in the posterior 

 and postero-lateral parts of the tongue, and in the soft palate 

 and its anterior arch, to which (and to some parts of which 

 exclusively) the glosso-pharyngeal is distributed, proves that 

 this also must be a gustatory nerve. In a female patient at 

 St. Bartholomew's Hospital, the left lingual branch of the fifth 

 nerve was divided in removing a portion of the lower jaw : she 

 lost both common sensation and the sensation of taste in the 

 tip and the anterior parts of the left half of the tongue, but 

 retained both in all the rest of the tongue. M. Lisfranc and 

 others have noted similar cases ; and the phenomena in them 

 are so simple and clear, that there can scarcely be any fallacy 

 in the conclusion that the lingual branches of both the fifth 

 and the glosso-pharyngeal nerves are gustatory nerves in the 

 parts of the tongue which they severally supply. 



This conclusion is confirmed by some experiments on ani- 

 mals, and, perhaps, more satisfactorily as concerns the sense of 

 taste in man, by observation of the parts of the tongue and 

 fauces, in which the sense is most acute. According to Valen- 

 tin's experiments made on thirty students, the parts of the 



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