554 THE NERVOUS SYSTEM. 



Physiology of the Glosso-Pharyngeal Nerve. 



The glosso-pharyngeal nerves (16, fig. 144), in the enume- 

 ration of the cerebral nerves by numbers according to the 

 position in which they leave the cranium, are considered as 

 divisions of the eighthpair of nerves , in which term are included 

 with them the pneumogastric and accessory nerves. But 

 the union of the nerves under one term is inconvenient, 

 although in some parts the glosso-pharyngeal and pneu- 

 mogastric are so combined in their distribution that it is 

 impossible to separate them in either anatomy or phy- 

 siology. 



The glosso-pharyngeal nerve appears to give filaments 

 through its tympanic branch (Jacobson's nerve), to the 

 fenestra ovalis, and fenestra rotunda, and the Eustachian 

 tube ; also, to the carotid plexus, and, through the petrosal 

 nerve, to the spheno-palatine ganglion. After communi- 

 cating, either within or without the cranium, with the 

 pneumogastric, and soon after it leaves the cranium, with 

 the sympathetic, digastric branch of the facial, and the 

 accessory nerve, the glosso-pharyngeal nerve parts into the 

 two principal divisions indicated by its name, and supplies 

 the mucous membrane of the posterior and lateral walls of 

 the upper part of the pharynx, the Eustachian tube, the 

 arches of the palate, the tonsils and their mucous mem- 

 brane, and the tongue as far forwards as the foramen 

 csecum in the middle line, and to near the tip at the sides 

 and inferior part. 



Some experiments make it probable that the glosso- 

 pharyngeal nerve contains, even at its origin, some motor 

 fibres, together with those of common sensation and the 

 sense of taste. Whatever motor influence, however, is 

 conveyed directly through the branches of the glosso- 

 pharyngeal, may be ascribed to the filaments of the pneu- 

 mogastric or accessory that are mingled with it. 



The experiments of Dr. John Beid, confirming those of 



