Chap, xv.i THE WRIST AND HAND. 257 



and interposes an effectual obstacle to reduction. 

 Dupuytren ascribes the difficulty to the altered rela- 

 tions of the lateral ligaments, ... to the spasm 

 of the muscles, and to the shortness of the member, in 

 consequence of which the force of extension has to be 

 applied very near to the seat of the dislocation. 

 Lisfranc found in an ancient luxation the tendon of 

 the long flexor so displaced inwards, and entangled 

 behind the extremity of the bone, as to prevent 

 reduction." The explanation most usually accepted 

 is that that ascribes the irreducibility to the 

 " button - hole action" of the sesamoid bones and 

 their tendons. 



Avulsion of one or more fingers may be effected 

 by severe violence. In such cases the finger torn off 

 usually takes with it some or all of its tendons. These 

 tendons are practically drawn out of the fore-arm, 

 and may be of considerable length. Billroth figures a 

 case where the middle finger was torn out, taking 

 with it the two flexor and extensor tendons in 

 their entire length. When one tendon only is torn 

 away with the finger, it is usually that of the flexor 

 profundus. 



Amputation at the wrist joint by double 

 flaps (see Heath's " Operative Surgery "). In the 

 dorsal flap would be cut the following tendons : the 

 extensores secimdi, indicis, communis, minimi cligiti. 

 and ulnaris, the radial nerve, and the dorsal branch 

 of the ulnar nerve. The two radial extensors will be 

 cut short in the radial angle of the flap, as will also be 

 the extensores ossis and primi. The radial artery will 

 be divided close to the radius. In the palmar flap 

 would be found the ulnar artery, the superficialis volee, 

 the ulnar and median nerves, the oppoiiens, flexor 

 brevis, and abductor pollicis in part, the flexor brevis, 

 opponens, and abductor minimi digiti in part (the 

 bulk of the opponens being left behind on the hand), 

 n 



