556 



NERVOUS SYSTEM. 



stant exposure, from abolition of the movements of winking by which the 

 tears are distributed over its surface and little foreign particles are removed, 

 and, in short, from absence of the protective action of the lids. In these 

 cases the lower lid may become slightly everted. The frontal portion of the 

 occipito-frontalis, the attrahens aurem, and the corrugator supercilii muscles, 

 are also paralyzed. The most prominent symptom of paralysis of these mus- 

 cles is inability to corrugate the brow upon one side. 



Paralysis of the muscles that dilate the nostrils has been shown to have 

 an important influence upon respiration through the nose. It was the syn- 

 chronism between the acts of dilatation of the nostrils and the movements of 

 inspiration which first led Charles Bell to regard the facial as a respiratory 

 nerve. In instances of complete paralysis of the nostril of one side, there is 

 frequently some difficulty in inspiration, even in the human subject. 



Charles Bell and others have also noted an interference with olfaction, 

 due to the inability to inhale with one nostril, in cases of facial paralysis. 



FIG. 801. 



FIG. 202. 



FIG. 203. 



FIG. 204. FIG. 205. FIG. 206. 



Expressions of the face produced by contraction of the muscles under electrical excitation (Le Bon, 



after Duchenne). 



Fig. 201, front view of the face in repose. 

 Fig. 202, profile view. 



Fig. 203, expression of laughter upon one side, produced by contraction of the zygomaticus major. 

 Fig. 204, expression of fear, produced by contraction of the frontal muscle and the depressors of the 



lower jaw. 



Fig. 205, expression of fear, profile view. 

 Fig. 206, expression of fear and great pain, produced by contraction of the corrugator supercilii and 



the depressors of the lower jaw. 



The influence of the nerve in the act of conveying odorous emanations to the 

 olfactory membrane is sufficiently evident, after what has been said con- 

 cerning the action of the facial in respiration. 



The effects of paralysis of the other superficial muscles of the face are 

 manifested in the distortion of the features, on account of the unopposed 

 action of the muscles upon the sound side, a phenomenon which is suf- 



