544 



THE CRANIAL NERVES. 



aqueduct of Fallopius, or involves the whole of its central origin, its 

 consequences extend uniformly over one side of the face, forming a com- 

 plete unilateral facial paralysis. 



The external signs of paralysis of the facial nerve from disease in 

 man are, in general, the same with those which follow experimental 

 division of this nerve in animals. The main peculiarity depends upon 

 the greater development of the facial muscles in man as the organs of 

 expression. The most marked effect, therefore, of this disease in the 

 human subject, is a loss of expression on the paralyzed side of the face. 



Fig. 177. 



FACIAL PARALYSIS of the right side. 



All the features have a collapsed and flaccid appearance. The eyelids 

 remain motionless, and the eye is constantly open, not only on account 

 of the impossibility of bringing down the upper e^yelid, but also because 

 the lower lid sinks down more or less below the level of the cornea ; 

 thus giving to the eye a staring, vacant appearance. The act of winking 

 is no longer performed upon the affected side. Owing to the paralyzed 

 condition of the frontalis and superciliary muscles, all the characteristic 

 lines and wrinkles on this side disappear, and the forehead and eyebrow 

 become smooth and expressionless. The same thing is true of the 



