FACIAL NERVE. 153 



most other experimenters, have also demonstrated the sen- 

 sibility of the nerve after it has passed out of the cranial 

 cavity, 1 except the inferior branch, in which Magendie and 

 others have found no evidences of pain on irritating it in 

 living animals. 2 Experiments have further shown that the 

 facial derives its sensibility in greatest part from the fifth 

 pair ; for section of the latter within the cranial cavity has 

 been found by Magendie to destroy the sensibility pf the 

 seventh. 3 It is probable, however, from other experiments, 

 by Bernard, that the pain produced by section of the fifth 

 interfered with the experiment, and that a part of the sensi- 

 bility of the facial is derived from a communicating branch 

 from the pneumogastric. Bernard exposed the facial, with 

 this communicating branch, and found it sensitive ; but af- 

 ter division of the branch from the pneumogastric, which 

 produced considerable pain, the sensibility of the facial was 

 destroyed. 4 



Direct observations upon the properties of the facial as it 

 penetrates the auditory canal, and before it has received any 

 anastomosing branches from sensitive nerves, must be to a 

 certain extent unsatisfactory. All who have experimented 

 upon the nerves know that the pain and depression which 

 attend so serious an operation as that of exposing the roots 

 of a nerve in the cranial cavity are sufficient to render it 

 doubtful whether the parts be in a condition to exhibit a 

 slight degree of sensibility, which the nerves may possess 

 when perfectly normal. Magendie B and Bernard," who have 

 exposed the roots of origin of the facial, state unreservedly 

 that they are absolutely insensible ; but Longet very justly 



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



2 MAGENDIE, Lefons sur les fonctions et les maladies du systeme nerveux, Paris, 

 1841, tome ii., p. 181. 



3 MAGENDIE, op. tit., p. 222. 



4 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, Paris, 

 1858, tome ii., p. 28. 



6 MAGENDIE, Systeme nerveux, Paris, 1841, tome ii., p. 208. 

 6 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 28. 



