OF THE WRIST AND BACK OF HAND. 161 



radio-ulnar, the radio-carpal, which exist between the 

 lower end of the radius, the scaphoid, and semilunar 

 bones. The synovial membrane of this articulation is 

 also extended over the cuneiform bone and the inter- 

 articular fibre-cartilage between the ulna and that bone; 

 the intercarpal and carpo-rnetacarpal joints, which in- 

 clude the anterior articular surfaces of the cuneiform, 

 semilunar, and scaphoid, the entire unciform, os magnum, 

 and trapezoid, with the bases of the four inner metacar- 

 pals, have a common synovial membrane, whilst the 

 pisiform and the trapezium have one each. Of these 

 articulations the most important to the surgeon is the 

 radio-carpal, as dislocation of the hand and carpus from 

 the radius, either backwards or forwards, takes place 

 here. Moreover, amputation is occasionally performed 

 at this joint. 



Fracture of the radius just above the articulation 

 (Colles's fracture), is almost always transverse, and in 

 young subjects is a separation of the lower epiphyses. 

 The deformity is well marked ; the result of the com- 

 bined action of the supinator longus, extensors of thumb, 

 and radial extensors of the wrist, causes the lower frag- 

 ment to make a partial rotation on its transverse axis. 



In examining the lower end of the forearm, in cases 

 of injury, it must be remembered that the head of the 

 ulna is prominent in pronation, and its styloid process in 

 supination, owing to the rotation of the radius at its in- 

 ferior radio-ulnar articulation. 



Amputation at the wrist-joint may be performed either 

 by a semilunar dorsal flap, and an anterior, formed from 

 the palm, or by rectangular flaps. The knife may get 

 notched against the pisiform bone, so that some little 

 neatness is necessary in avoiding it. The styloid pro- 



