552 THE NERVOUS SYSTEM. 



and form of the orifices of the puncta lachrymalia. From 

 these circumstances, the sense of sight is impaired. 



The sense of hearing, also, is impaired in many cases 

 of paralysis of the facial nerve ; not only in such as are 

 instances of simultaneous disease in the auditory nerves, 

 but in such as may be explained by the loss of power in 

 the muscles of the internal ear. The sense of smell is 

 commonly at the same time impaired through the inability 

 to draw air briskly towards the upper part of the nasal 

 cavities, in which part alone the olfactory nerve is distri- 

 buted ; because, to draw the air perfectly in 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 paralysis 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 tympani. This 

 result, which has been observed in many instances of 

 disease of the facial nerve in man, appears explicable only 

 by the influence which, through the chorda tympani, it 

 exercises on the movements of the lingualis and the 

 adjacent muscular fibres of the tongue ; and, according to 

 some, or probably in some animals, on the movements of 

 the stylo-glossus. We may therefore suppose that the 

 accurate movement of these muscles in the tongue is in 

 some way connected with the proper exercise of taste. 



Together with these effects of paralysis of the facial 

 nerve, the muscles of the face being all powerless, the 

 countenance acquires on the paralyzed side a characteristic, 

 vacant look, from the absence of all expression : 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 

 unmeaning stare. All these peculiarities increase, the 

 longer the paralysis lasts ; and their appearance is exag- 

 gerated when at any time the muscles of the opposite side 

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



