196 NERVOUS SYSTEM. 



in deglutition, by Waller and Prevost, it was found, that after 

 section of the fifth upon both sides, it was impossible to ex- 

 cite movements of deglutition by stimulating the mucous 

 membrane of the velum palati. After section of the superior 

 laryngeal branches of the pneumogastrics, no movements 

 of deglutition followed stimulation of the mucous membrane 

 of the top of the larynx. In these experiments, w r hen the 

 fifth was divided on one side, stimulation of the velum upon 

 the corresponding side had no effect, while movements of 

 deglutition were produced by irritating the velum upon the 

 sound side. 1 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 which pass from the fifth to the mu- 

 cous membrane through Meek el's ganglion. 



Remote Effects of Division of the Trifacial. After the 

 ordinary operation of dividing the fifth pair in the cranial 

 cavity, the immediate loss of sensibility of the integument 

 and mucous membranes of the face and head is usually sup- 

 plemented by serious disturbances in the nutrition of the 

 eye, the ear, and the mucous membranes of the nose and 

 mouth. This curious fact was noted by Magendie, in 1824 ; a 

 but it was observed by Mayo, in 1823, in a case of paralysis 

 of the fifth in the human subject. 3 At a period varying 

 from a few hours to one or two days after the operation, the 

 eye upon the affected side becomes the seat of purulent in- 

 flammation, the cornea becomes opaque, ulcerates, the hu- 

 mors are discharged, and the organ is destroyed. Conges- 

 tion of the parts is usually very prominent a few hours after 



1 WALLER ET PREVOST, J&tude relative aux nerfs sensitifs qui president anx phe- 

 nomenes reflexes de la deglutition. Archives de physiologie, Paris, 1870, tome iii., 

 p. 346, et seq. 



2 Journal de physiologie, Paris, 1824, tome iv., pp. 178, 304. 



3 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 

 1823, p. 12. 



