Wrist and Hand. 105 



centre of the line uniting the two styloid processes, and 

 the other, the base of the second metacarpal bone. The 

 knife, inserted over the base of this metacarpal bone, is 

 carried obliquely upwards to the first landmark and then 

 vertically up to the back of the forearm for about one and 

 a half inches. This incision skirts the extensor indicis ten- 

 don which is drawn aside, and the knife is inserted .between 

 this tendon and that of the extensor carpi radialis brevior. 

 The incision is deepened at once to the carpus and to the 

 posterior surface of the radius, avoiding the extensor se- 

 cundi tendon at the upper part of the wound. The pos- 

 terior ligament of the joint is then opened and the bones 

 removed. Since the os magnum is the central bone, the 

 division of its neck by bone forceps will permit ready ac- 

 cess to the rest of the carpus. Should there not be suf- 

 ficient room to remove the bones through the posterior 

 wound, an ulnar incision may be made on the ulnar side of 

 the extensor carpi ulnaris, extending from a point one 

 inch above the tip of the ulnar styloid process, to a point a 

 little above the base of the metacarpal bone of the little 

 finger. 



Dislocation at the wrist joint is rare, and yet, one 

 would expect, from the shape of the articular surfaces, 

 that it would be very common, exposed, as the hand is, to 

 so many injuries from falls, etc. One factor in the pre- 

 vention of dislocation at this joint is, that the carpus is 

 composed of a number of bones, for, had these bones been 

 replaced by one bone, then vibrations, the result of force 

 applied to the hand, would have been intensified and a 

 fracture or a dislocation would have had greater chance 

 of occurring than with the existing condition of a number 

 of bones bound together, yet separated, so that the vibra- 

 tions are diffused and lessened, before the wave strikes 

 the wrist joint. The main reason, however, that disloca- 



