THE GLOSSO-PHARYNGEAL NERVE. 435 



acquires on the paralyzed side a characteristic, vacant look, 

 from the absence of all expression : the angle of the mouth ig 

 lower, and the paralyzed half of the mouth looks longer than 

 that on the other side : the eye has an unmeaning stare. All 

 these peculiarities increase, the longer the paralysis lasts ; and 

 their appearance is exaggerated when at any time the muscles 

 of the opposite side of the face are made active in any expres- 

 sion, or in any of their ordinary functions. In an attempt to 

 blow or whistle, one side of the mouth and cheek acts prop- 

 erly, 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 powerless, 

 and food lodges between the cheek and gum. 



As a nerve of expression, the seventh nerve must not be 

 considered independent of the fifth nerve, with which it forms 

 so many communications ; for, although it is through the facial 

 nerve alone that all the muscles of the face are put into their 

 naturally expressive actions, yet the power which the mind 

 has of suppressing or controlling all these expressions can only 

 be exercised by voluntary and well-educated actions directed 

 through the facial nerve with the guidance of the knowledge 

 of the state and position of every muscle, and this knowledge 

 is acquired only through the fifth nerve, which confers sensi- 

 bility on the muscles, and appears, for this purpose, to be more 

 abundantly supplied to the muscles of the face than any other 

 sensitive nerve is to those of other parts. 



Physiology of the Olosso-Pharyngeal Nerve. 



The glosso-pharyngeal nerves (4, Fig. 151), in the enume- 

 ration of the cerebral nerves by numbers according to the po- 

 sition in which they leave the cranium, are considered as di- 

 visions 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 anatomy or physiology. 



The glosso-pharyngeal nerve appears to give filaments 

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

 ovalis, and feuestra 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 pneumogastric, and soon after 

 it leaves the cranium, with the sympathetic, digastric branch 

 of the facial, and the accessory nerve, the glosso-pharyngeal 



