FACIAL XERVE. 457 



of the lips ; that is, to the superficial muscles of the face, which are 

 concerned in the production of expression. (Fig. 151.) 



The facial, consequently, is the Fi 151 



motor nerve of the face. It has 

 nothing to do with transmitting 

 sensitive impressions, since it has 

 been frequently shown that after 

 section of the fifth pair, the facial 

 remaining entire, the sensibility of 

 the face is completely lost ; so that 

 the integument may be cut, pricked, 

 pierced, or lacerated, without any 

 sign of pain being exhibited by the 

 animal. The facial, therefore, does 

 not transmit sensation from these 

 parts ; and its division, which was 

 formerly resorted to in cases of 

 tic douloureux, is accordingly alto- 

 gether incapable of relieving neuralgic pains. 



This nerve, however, is directly connected with muscular action, 

 since mechanical or galvanic irritation of its fibres produces con- 

 vulsive twitching in the ears, nostrils, lips, and cheeks. 



If the facial nerve be divided in one of the lower animals, as, for 

 example, in the cat, immediately after its emergence from the 

 stylo-mastoid foramen, it will be found that complete muscular 

 paralysis has occurred in all those parts to which the nerve is dis- 

 tributed, while the power of sensation remains unimpaired. The 

 animal is incapable of moving the ear, which remains constantly in 

 the same position. There is also incapacity of closing the eyelids, 

 owing to paralysis of the orbicularis oculi, and the eye accordingly 

 remains constantly open, even when the opposite eye is closed ; 

 as during sleep, or in the act of winking. If the conjunctiva be 

 touched, the animal feels the irritation, and endeavors to escape 

 from it ; but the eyeball is only drawn partially backward into the 

 socket by the action of the recti muscles, and the third eyelid 

 pushed partly across the cornea. The complete closure of the eye 

 is impossible. It will be observed, accordingly, that precisely oppo- 

 site effects are produced upon the eyelids by paralysis of the oculo- 

 motorius nerve, and by that of the facial. In the former instance, 

 owing to the paralysis of the levator palpebras superioris, the eye 

 is always partially closed ; in the latter, owing to paralysis of the 



