REMOTE EFFECTS OF DIVISION OF THE TRIFACIAL 527 



on the influence of this nerve on the general sensibility and the sense 

 of taste in the tongue have been made by dividing the lingual branch of 

 the inferior maxillary division. When this branch is irritated, there are 

 evidences of intense pain. When it is divided, the general sensibility 

 and the sense of taste are* destroyed in the anterior portion of the 

 tongue. It will be remembered, however, that the chorda tympani 

 joins the lingual branch of the fifth as it passes between the pterygoid 

 muscles, and that section of this branch of the facial abolishes the sense 

 of taste in the anterior two-thirds of the tongue. If the gustatory prop- 

 erties of the lingual branch of the fifth be derived from the chorda 

 tympani, lesions of the fifth not involving this nerve would be followed 

 by loss of general sensibility, but the taste would be unaffected. This 

 has been shown to be the fact, by cases of paralysis of general sensibility 

 of the tongue without loss of taste in the human subject, which will be 

 discussed more fully in connection with the physiology of gustation. 



Among the immediate effects of section of the fifth, is interference 

 with the reflex acts of deglutition. After section of the superior laryn- 

 geal branches of the pneumogastrics, no movements of deglutition 

 follow stimulation of the mucous membrane of the top of the larynx. 

 When the fifth is divided on one side, stimulation of the velum on the 

 corresponding side has no effect, while movements of deglutition are 

 produced by irritating the velum on the sound side. These experiments 

 show that the fifth nerve is important in the reflex phenomena of 

 deglutition as a sensory nerve, conveying the impression from the 

 velum palati to the nerve-centres. This action probably takes place 

 through filaments that pass from the fifth to the mucous membrane 

 through Meckel's ganglion. 



Remote Effects of Division of the Trifacial. After section of the 

 fifth nerve in the cranial cavity, the immediate loss of sensibility of the 

 integument and mucous membranes of the face and head usually is 

 supplemented with serious disturbances in the nutrition of the eye, the 

 ear and the mucous membranes of the nose and mouth. After a period 

 varying between a few hours and one or two days following the operation, 

 the eye on the affected side becomes the seat of purulent inflammation, 

 the cornea becomes opaque and ulcerates, the humors are discharged 

 and the organ is destroyed. Congestion of the parts usually is very 

 prominent a few hours after division of the nerve. At the same time 

 there is an increased discharge from the mucous membranes of the nose 

 and mouth on the affected side, and ulcers appear on the tongue and 

 lips. It is probable, also, that disorders in the nutrition of the auditory 

 apparatus follow the operation, although these are not so prominent. 

 Animals .affected in this way usually die in fifteen to twenty days. 



