460 THE CRANIAL NERVES. 



posterior foramen lacerum in company with the pneumogastric and 

 spinal accessory. While in the jugular fossa it presents a gangliform 

 enlargement, called the ganglion of Andersch, below the level of 

 which it receives branches of communication from the facial and 

 the spinal accessory. It then runs downward and forward, and is 

 distributed to the mucous membrane of the base of the tongue, 

 pillars of the fauces, soft palate, middle ear, and upper part of the 

 pharynx. It also sends some branches to the constrictors of the 

 pharynx and the neighboring muscles. Longet has found this 

 nerve at its origin to be exclusively sensitive ; but below the level 

 of its ganglion it has been found by him, as well as by various 

 other observers, to be both sensitive and motor, owing to the fibres 

 of communication received from the motor nerves mentioned above. 

 Its final distribution is, however, as we have seen, principally to 

 sensitive surfaces. The principal office of this nerve is to impart 

 the sense of taste to the posterior third of the tongue, to which it is 

 distributed. It also presides over the general sensibility of this 

 part of the tongue, as well as that of the fauces and pharynx. 



Dr. John Reid, 1 who has performed a great variety of experiments 

 upon this nerve, comes to the following conclusions in regard to it. 

 First, that it is essentially a sensitive nerve, since there are unequi- 

 vocal signs of pain when it is pricked, pinched, or cut. Second, 

 that irritation of this nerve produces convulsive movements of the 

 throat and lower part of the face ; but that these movements are, in 

 great measure, not direct, but reflex in their character, since they 

 will take place equally well after the glosso-pharyngeal has been 

 divided, if the irritation be applied to its cranial extremity. Third, 

 that this nerve supplies the special sensibility of taste to a portion 

 of the tongue ; but that it is not the exclusive nerve of this sense, 

 since the power of taste remains, after it has been divided on both 

 sides. 



There are certain reflex actions, furthermore, which take place 

 through the medium of the glosso-pharyngeal nerve. After the 

 food has been thoroughly masticated, it is carried, by the move- 

 ments of the tongue and sides of the mouth, through the fauces, 

 and brought in contact with the mucous membrane of the pharynx. 

 This produces an impression which, conveyed to the medulla 

 oblongata by the filaments of the glosso-pharyngeal, excites the 



1 In Todd's Cyclopaedia of Anatomy and Physiology, article Glosso-pharynyeal 

 Nerve. 



