EXTERNAL BRANCHES OF THE FACIAL. 165 



tical physician. When facial palsy affects one side and is 

 complete, the angle of the rnouth is drawn to the opposite 

 side, the eye upon the affected side is widely and perma- 

 nently opened, even during sleep, and the face has upon 

 that side a peculiarly expressionless appearance. When a 

 patient affected in this way smiles or attempts to grimace, 

 the distortion is much increased. The lips are paralyzed 

 upon one side, which sometimes causes a flow of saliva- from 

 the corner of the mouth. In the lower animals that use 

 the lips in prehension, paralysis of these parts interferes 

 considerably with the taking of food. The flaccidity of the 

 paralyzed lips and cheek in the human subject sometimes 

 causes a puffing movement with each act of expiration, as if 

 the patient were smoking a pipe. 



We have already seen that the buccinator is not supplied 

 by filaments from the nerve of mastication, but is animated 

 solely by the facial. Paralysis of this muscle interferes ma- 

 terially with mastication, from a tendency to accumulation 

 of the food between the teeth and the cheek. Patients 

 complain of this difficulty, and sometimes keep the food 

 between the teeth by pressure with the hand. In the rare 

 instances in which both facial nerves are paralyzed, there is 

 very great difficulty in mastication from the cause just men- 

 tioned. 



The functions of the external branches of the facial are 

 thus sufficiently simple ; and it is only as its deep branches 

 affect the taste, the movements of deglutition, etc., that it is 

 difficult to ascertain their exact office. As this is the nerve 

 of expression of the face, it is in the human subject that 

 the phenomena attending its paralysis are most prominent. 

 "When both sides are affected, the appearance is most re- 

 markable, the face being absolutely expressionless and look- 

 ing as if it had been covered with a mask. 



