300 St. J. Brooks, 



have been a favourite method with Henle x ) ; I am not aware, however, 

 if the nerves of the dorsum manûs have been previously treated in 

 this way under water. When the preparation is placed under water 

 and traction is made on the trunks of the radial and ulnar nerves 

 alternately, the general distribution of each nerve and many of the 

 finer branches can be seen without further dissection ; this applies 

 more particularly to the back of the hand ; in the fingers, on account 

 of the tough and opaque nature of the fascia, the results are not 

 so good. 



I have examined the nerves by the above method in six hands 

 and have also succeeded in seeing the crossing of the nerves in four 

 other hands which I dissected in the ordinary way. In another of the 

 six cases dissected under water I found the radial and ulnar nerves 

 crossing in their distribution to the extent of three fingers (index, 

 middle and ring), in the others the area of skin thus doubly supplied 

 was much smaller, in one case being not more than a quarter of an 

 inch in breadth. While regarding the amount of crossing of the two 

 nerves which is displayed in fig. 1, as unusually large, I am inclined to 

 think that the amount of skin on the back of the fingers, which is 

 supplied by the dorsal digital nerves, is fairly typical. In five of the 

 ten cases the dorsal branches of the ulnar nerve were traced to the 

 nail of the little finger, and, from the size of the nerves, they pro- 

 bably extended equally far in the other five cases also. In the thumb, 

 as is well known, the branches of the radial regularly extend as far 

 as the nail. In the index and ring fingers I found that the dorsal 

 nerves usually reached the second inter-phalangeal joint. In the middle 

 finger the dorsal nerves generally extend only as far as the first inter- 

 phalangeal articulation, but in one case I found a branch of the ulnar 

 nerve, and in another subject, a combined branch of the ulnar and 

 radial nerves, reaching as far as the ungual phalanx of this digit. 



In fig. 2 2 ) of Létiévant's book the dorsum of the ungual phalanx 

 of the thumb is shown to be profoundly affected by section of the 

 median nerve. This led me to pay particular attention to the distri- 

 bution of the palmar digital branches of the median to the thumb. 



*) Handbuch der Nervenlehre. 1879. Fig 285, 286, 291 u. 292. 

 ') This figure is reproduced in the accompanying plate; see fig. 6. 



