SPECIAL PHYSIOLOGY. 39 



Glosso-pharyngeal Nerve. This is a mixed nerve even 

 from its origin (Mueller, Bernard) ; however, Longet consid- 

 ers this primarily a sensory nerve, possessing no derived 

 motor filaments. If experiments on animals do not always 

 allow of the determination of rnotory properties (Jolyet), still 

 the existence of these can be deduced from the rapidity with 

 which these lose their power of excitability (Biffi, Morganti, 

 Schiff). The glosso-pharyngeal presides over the move- 

 ments of the pharynx, (as also the facial, pneumo-gastric, and 

 spinal), over the general sensibility of the region of the 

 fauces, of the base of the tongue, and finally over the special 

 or gustatory sensibility of the base of the tongue (see organs 

 of special sense, taste). 



Pneumo-gastric (nervus vagus, par vagum). Bischoff and 

 Longet are unwilling to admit in the roots of this nerve any 

 other than sensory filaments ; still experiments by Bernard, 

 Van Kempen, Vulpian, and Jolyet prove that the pneumo- 

 gastric is both motory and sensory, from its origin ; it is also 

 true that it receives a large number of motory anastomoses 

 from the neighboring nerves. 



The very complicated physiology of this nerve, taking 

 into consideration its very complex anatomical distribution, 

 is found to vary with each organ to which its branches are 

 sent off (see circulation, digestion, and respiration). We 

 can here only generalize upon these functions. The pneumo- 

 gastric might be called a mixed tri- visceral nerve, or, in other 

 words, it affords sensibility and movement to three great 

 viscera (heart, lungs, and stomach), and also to their appen- 

 dages. But it must be remembered that the sensibility 

 afforded by this nerve is generally obtuse, and in no wise 

 localized, and gives vague sensations of the kind called 

 general (see farther on ; physiology of the encephalon), or 

 may give rise to reflected actions of which the mind is un- 

 conscious. Consequently the movements over which it pre- 

 sides are mostly reflex, and but slightly under the power of 

 the will. 



In the apparatus for respiration, the pneumo-gastric af- 

 fords sensibility to the glottis, the trachea, and the lung (the 

 centripetal conductor of the desire of breathing) ; also motion 

 to the glottis (movements of respiration arid not of phona- 

 tion. Cl. Bernard) ; also to the smooth, muscular fibres of 

 th<e trachea and bronchi (Williams, Paul Bert). 



In the central apparatus for circulation, it gives sensory 

 and moderating cardiac nerves (see circulation). 



