678 FOURTH REPORT — 1834. 



vern the actions of the face, and preside over the sensibilities of 

 its different organs and surfaces. The first function is performed 

 by the facial portion of the seventh nerve and a portion of the 

 fifth. The second function is performed by the large portion of 

 the fifth pair of nerves. Thus the fifth nerve possesses two di- 

 stinct properties of transmission, one voluntary, the other sen- 

 tient, in consequence of its having two distinct roots. One of 

 these roots, the lai-gest, has a ganglion attached to it, and is ex- 

 clusively a sentient nerve. The smaller root has no ganglion, 

 is insensible, and governs the motions of those muscles which it 

 supplies. The first fact is easily gained by experiment, but the 

 second is admitted upon other grounds, for the smaller root can- 

 not be experimented upon in the living animal. It is to be ob- 

 served that the larger root of the fifth nerve is divided into three 

 branches, spread and ramified over the face, and frequently con- 

 nected in its ramifications with branches of the seventh nerve ; 

 so that unless the experimental tests be applied to distinct 

 branches, no certain response can be obtained as to their several 

 properties. 



Pricking or pinching the trifacial nerve was attended with 

 instantaneous indications of consciousness ; when its branches 

 were divided, all sensibility ceased in the parts which they supply. 

 The lower divided ends made no response when bruised, but the 

 upper indicated sensation. The motions of the face, however, 

 still remained unimpaired, until the seventh nerve was divided 

 as near its origin as possible, when the organs which it supplies 

 became permanently motionless. When this nerve was slightly 

 pinched in its entire state, those muscles exclusively which it 

 supplies were seen to be convulsed, without any general effort ; 

 when the compression was increased, and continued for a few 

 moments, signs of uneasy respiration occurred. Pricking this 

 nerve with a needle and cutting through it produced no struggle 

 whatever, as is the case with the trifacial nerve. When the 

 lower end of the nerve, after division, was irritated, no movement 

 followed ; but on compressing the upper end, the same signs 

 were exhibited as when the nerve was irritated in its entire state. 



2. Experiments xipon the Nerviis Vagus. — In the year 1820 

 Mr. Broughton experimented upon this nerve ; the results were 

 published in the Quarterly Journal of Science of the Royal In- 

 stitution. It was found to be insensible when slightly pinched, 

 pricked, or divided. The present experimental investigation 

 confirmed this remark. It was also on the former, as well as 

 xipon the recent occasion, clearly shown that, when a forcible 

 compression was continued a few moments upon thenervus vagus, 

 arespiratory effort followed, and an act of deglutition, with a 



