96 [May 15, 



finger cannot be placed in apposition with the annular, but remains 

 apart at an angle of 10 or 15 degrees. At the same time paralysis 

 of the abductor and adductor muscles of the other fingers takes 

 place. 



The index and thumb alone retain some of their powers of adduc- 

 tion and abduction ; the former probably from the action of its proper 

 extensor ; the latter from its abduction not being animated by the 

 ulnar nerve. 



When paralysis of these muscles is complete, the appearance of 

 the hand, when the fingers are in extension, is pathognomic, and as 

 follows : 



The little finger in complete adduction at about an angle of 40 

 from the annular, which is likewise a little apart from the median. 

 Both these fingers are slightly flexed and incapable of complete ex- 

 tension. The flexor muscles are much weakened, as might be anti- 

 cipated from the distribution of the ulnar nerve. In addition, the 

 flexion movements of the thumb and the extensor power of this and 

 all the fingers are considerably weakened. 



The tendency of the fingers to semiflexion, and the inability of 

 the little, the annular, and even to a slight extent the median finger 

 to accomplish complete extension is probably referable to the state 

 of tonicity of the paralysed flexors. The weakness of the extensor 

 and flexor powers of the thumb are not, in my opinion, sufficiently 

 accounted for by the lost power of its adductor muscle. Still less 

 can we account for the diminished power of extension of the other 

 fingers by any direct or descending action of the ulnar nerve. I am 

 led therefore to refer the diminished power, in this case, of the ex- 

 tensor muscles of the fingers to reflex action of the ulnar nerve. In 

 support of this view, I may state that I have not unfrequently expe- 

 rienced, after vibrating the ulnar nerve at the elbow, a great lassitude 

 of the whole limb, particularly marked over the deltoid muscle, to 

 so great an extent as to occasion much discomfort for at least an hour 

 afterwards. 



Vaso-motory symptoms. Under this head I include all the per- 

 turbations of temperature of the integuments animated by the ulnar 

 nerve, which attend its compression. 



Mechanical irritation of this nerve, such as vibrating it, will fre- 

 quently cause an immediate fall of 0'5 Cent, to 1'0 Cent, of the 



