CHORDA TYMPANI. 239 



takable phenomena noted in cases of affection of the chorda 

 tympani in the human subject. 



It seems tolerably certain, first, that the gustatory fila- 

 ments of the lingual branch of the fifth are derived exclu- 

 sively from the chorda tympani ; second, that the chorda 

 tympani, viewed as a gustatory nerve, is really a branch of 

 the facial ; third, that many cases of paralysis of the entire 

 large root of the fifth, in the human subject, present loss of 

 general sensibility in the tongue and no alteration of taste ; 

 and fourth, that paralysis of the facial, behind the origin of the 

 chorda tympani, is attended with loss of taste in the anterior 

 two-thirds of the tongue, without any affection of the general 

 sensibility of this organ. 



We have made the above statement with all the necessary 

 qualifications, and with an appreciation of the value of the 

 various experiments bearing upon the question. It is fair to 

 say that section of the fifth at or near the ganglion of Gasser 

 is said to abolish the sense of taste in the anterior portion of 

 the tongue, as well as the general sensibility ; but it must be 

 remembered that it is difficult to make observations on the 

 sense of taste in the lower animals, especially after paralysis 

 of sensation in the tongue ; and that numerous cases are on 

 record, to which we have already referred, in which, in the 

 human subject, general sensibility in the tongue was absent, 

 the sense of taste remaining. On the other hand, in certain 

 cases of paralysis of the facial, the sense of taste is absent, 

 while general sensibility is intact. In view of this fact, we 

 cannot admit the proposition of Schiff, that the gustatory 

 nerves of the anterior portion of the tongue emerge from 

 the encephalon with the roots of the fifth. 1 As regards the 

 mechanism of the action of the chorda tympani in gustation, 

 we cannot adopt the view of Bernard, 3 that it acts as a 



1 SCHIFF, Lefons sur la physiologie de la digestion, Florence et Turin, 1867, 

 tome i., p. 140 ; and, Neue Untersuchungen uber die Geschmaksnerven des vorde- 

 ren Theiles der Zunge. Untersuchungen zur Naturlehre, etc., Giessen, 1870, Bd. 

 x., S. 406, et seq. 



* BERNARD, Systbne neryeux, Paris, 1858, tome ii., p. 111. 

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