326 MR. BELL ON THE NERVES OF THE FACE. 



I was consulted in the case of a lady with an uncommon disease in the side 

 of the head : the description of her condition puzzled me very much; there was 

 so much said of tumours with pulsation on the head and face. But when I 

 saw and examined her, the mystery disappeared ; she had powerful spasms of 

 the temporal and masseter muscles, which rose and swelled, under the excite- 

 ment of a disease of the cheek, and with a pressure of the jaws so powerful as 

 to displace the teeth. During this violent spasm of the muscles supplied by 

 the fifth nerve, the motions of the features were free and unconstrained under 

 the influence of the portio dura of the seventh nerve. 



I have the precise counter-part to this morbid condition of the muscles of 

 mastication in the case of a poor man now under my care. He has a disease 

 affecting the fifth nerve of the left side, attended with the loss of sensibility of 

 the side of the face and of the surfaces of the eye. In him there is no motion 

 of the muscles of the jaw of the affected side. In chewing, the action is only 

 on the right side of the head ; the masseter muscle and temporal muscle of the 

 left side do not rise or bulge out as in their natural actions ; but his command 

 over his features is perfect through the operation of the portio dura. It ap- 

 pears, therefore, that the disease of the fifth nerve, which has destroyed the 

 sensibility on one side of the face, has caused a loss of motion in the muscles 

 of the jaw on the same side. 



A more frequent occurrence establishing the distinction of motions influenced 

 by the fifth and seventh nerves, is presented in the case of paralysis of the portio 

 dura ; for then all the muscles waste but those supplied by the fifth. In the 

 case referred to, of the man wounded by the horn of an ox, in whom the portio 

 dura was torn, and who had the skin of his forehead, side of the nose, cheek 

 and lips, deprived of all fleshiness and substance, and in fact wasted to mere 

 skin, the muscles of the jaw were entire and prominent ; and on introducing 

 the finger into the mouth and making him imitate the motions of mastication, 

 a weak contraction could be felt in the cheek*. 



These facts close the evidence of the fifth nerve being a double nerve ; not 

 only the nerve of sensibility to the head and face, but a muscular nerve to the 

 muscles of the jaws, active in mastication, and otherwise useful in all animals 



* How often a question has occurred as to this motion in the cheeks, may be seen on referring to 

 cases, p. 123, Exposition, &c. and p. 57, Appendix, 1st edition. 



