PHYSIOLOGY OF THE CRANIAL NERVES. 539 



this direction, the action of the dilators and compressors of the nostrils 

 should be perfect. 



Lastly, the sense of taste is impaired, or may be wholly lost in para- 

 lysis of the facial nerve, provided the source of the paralysis be in some 

 part of the nerve between its origin and the giving off of the chorda tym- 

 pani. This result, which has been observed in many instances of disease 

 of the facial nerve in man, appears explicable on the supposition that the 

 chorda tympani is the nerve of taste to the anterior two-thirds of the 

 tongue, its fibres being distributed with the so-called gustatory or lin- 

 gual branch of the fifth. Some look upon the chorda as partly or en- 

 tirely made up of fibres from the fifth nerve, and not strictly speaking 

 as a branch of the facial; others consider that it receives its taste fibres 

 from communications with the glosso-pharyngeal. 



Together with these effects of paralysis of the facial nerve, the mus- 

 cles of the face being all powerless, the countenance acquires on the 

 paralyzed side a characteristic, vacant look, from the absence of all ex- 

 pression: the angle of the mouth is lower, and the paralyzed half of the 

 mouth looks longer than that on the other side; the eye has an unmean- 

 ing stare. All these peculiarities increase, the longer the paralysis lasts; 

 and their appearance is exaggerated when at anytime the muscles of the 

 opposite side of the face are made active in any expression, or in any of 

 their ordinary functions. In an attempt to blow or whistle, one side- 

 of the mouth and cheek acts properly, but the other side is motionless, 

 or flaps loosely at the impulse of the expired air; so in trying to suck, 

 one side only of the mouth acts; in feeding, the lips and cheek are pow- 

 erless, and food lodges between the cheek and gum. 



The Ninth, or Glosso-Pharyngeal Nerve. 



The glosso-pharyngeal nerves (ix., Fig. 341), in the enumeration of 

 the cerebral nerves by numbers according to the position in which they 

 leave the cranium, are considered as divisions of the eighth pair 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 pneumogastric are 

 so combined in their distribution that it is impossible to separate them 

 in either their anatomy or physiology. 



Distribution. The glosso-pharyngeal nerve gives filaments through 

 its tympanic branch (Jacobson's nerve), to the fenestra ovalis, and fe- 

 nestra rotunda, and the Eustachian tube; also, to the carotid plexus, and, 

 through the petrosal nerve, to the spheno-palatine ganglion. After 

 communicating, either within or without the cranium, with the pneu- 

 mogastric, and soon after it leaves the cranium, with the sympathetic, 

 digastric branch of the facial, and the accessory nerve, the glosso-pharyn- 

 geal nerve parts into the two principal divisions indicated by its name,. 



