154 NERVOUS SYSTEM. 



remarks that the conditions under which such observations 

 are made have not been, in his hands, sufficiently favor- 

 able to admit of a rigorous conclusion on this point. 1 The 

 testimony of direct experimentation is in favor of the in- 

 sensibility of the* facial at its origin. It is true that the 

 intermediary nerve of "Wrisberg has a certain anatomical 

 resemblance to the sensitive nerves, chiefly by virtue of its 

 ganglioform enlargement ; but direct experiments are want- 

 ing to show that it is actually sensitive. In view of this 

 fact, it is impossible to reason conclusively from its anatomi- 

 cal characters alone. 



The most convenient way to consider the functions of 

 the facial will be to take up seriatim the properties and dis- 

 tribution of its different branches. 



Functions of the Branches of the Facial within the Aque- 

 duct of Fallopius. The first branch, the large petrosal, is 

 the motor root of Meckel's ganglion. This will be referred 

 to again in connection. with the sympathetic system. The 

 second branch, the small petrosal, is one of the motor roots 

 of the otic ganglion of the sympathetic. It is thought by 

 Longet that this branch simply passes through the ganglion 

 to be distributed to the tensor tympani muscle. This au- 

 thor regards the small petrosal and the tympanic branch of 

 the facial as branches exclusively furnished by the interme- 

 diary nerve of Wrisberg, which he considers as the nerve of 

 the tympanum, and has called the " tympanic motor nerve." 

 This, however, is advanced as a mere supposition, not en- 

 tirely proven by experiments. 11 The third branch, the tym- 

 panic, is distributed exclusively to the stapedius muscle. 

 The second and third branches will be again considered in 

 connection with the physiology of the internal ear. 



According to the experiments of Savart, 3 paralysis of the 



1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 567. 



2 Ibid., p. 579. 



8 SAVART, Recherches sur les usages de la membrane du lympan et de Voreille 

 externe. Journal de physiologic, Paris, 1824, tome iv., p. 204. 



