THE ENCEPHALIC NERVES. 



127 



Fig. 37.* 



buted, and also puts a 

 stop to the movements 

 of mastication. Pain- 

 ful affections of the 

 face (neuralgia) have 

 their seat in the sensi- 

 tive branches of this 

 nerve. 



The portio dura of 

 the seventh pair is the 

 general motor nerve to 

 the face, (Fig. 37.) 

 The muscles supplied 

 by it are chiefly those 

 upon which the aspect 

 of the countenance and 

 the balance of the fea- 

 tures depend. It is 

 sometimes called the 

 nerve of expression. 

 The acts of closing the 

 eyelids and frowning 

 depend on this nerve. Subsequently to its entrance into the canal 

 from which it emerges, it receives sensory filaments from the fifth, 

 and some cervical nerves, which cause irritation of its several 

 branches to produce pain. Section of the nerve, at its emerging 

 from the stylo-mastoid foramen, is followed by paralysis of the 

 muscles of the face and eyelids. 



It was formerly thought to be the seat of neuralgia^ and was 

 upon several occasions cut. The only result was paralysis of that 

 side of theface^ total loss of control over the features, of the potter of 

 froivning, and of closing the eyelids. The portio dura is also the 

 channel of the reflex movements concerned in respiration, but it is 

 not at all concerned in mastication. 



The eighth pair of nerves is made up of three others, the glosso- 

 pharyngeal, the par vaguni or pneumogastric, and the spinal ac- 

 cessory, (Fig. 38.) The conclusions that have been arrived at by 

 physiologists in relation to these nerves, can alone be stated here. 



The glosso-pharyngeal is the sensitive nerve of the mucous mem- 

 brane of the fauces and of the root of the tongue, and in the latter 

 situation it ministers to taste and touch, as well as to common sensi- 

 bility ; and being the sensitive nerve of the fauces, it is probably 

 concerned in the feeling of nausea so readily excited by stimulating 

 the mucous membrane of this region. Such are its peripheral or- 



* Distribution of the facial nerve. 1. Facial nerve escaping from stylo-mastoid foramen. 

 For references, see Anatomy. 



