Chap, xiv.] THE FORE-ARM. 257 



neutralised by the pronator that is also connected 

 with it. The lower fragment will be adducted to 

 the ulna by the pronator quadratus, and its upper 

 end will be still further tilted towards that bone 

 by the action of the supinator longus upon the 

 styloid process. When the ulna is broken alone, 

 as, for example, about its middle, the upper frag- 

 ment may be drawn a little forwards by the 

 brachialis anticus, while the lower fragment will be 

 carried towards the radius by the pronator quad- 

 ratus. 



The displacement, however, in all cases is in- 

 fluenced as much by the direction of the violence as 

 by the action of muscles. When the fragments, 

 after fracture of one or of both bones, fall in towards 

 one another, so as to meet across the interosseous 

 space, attempts are sometimes made to separate the 

 broken ends and to preserve the integrity of the space 

 by the use of graduated pads. These pads, however, 

 if supplied with sufficient force to separate the frag- 

 ments, will probably compress one or both of the 

 arteries of the limb, and cause great distress by 

 pressure upon the median nerve. 



The fact that the bulk of the venous blood of the 

 fore-arm is returned by surface veins may explain the 

 ready occurrence of severe oedema in the limb when 

 fractures are treated with improperly-applied splints 

 or bandages. Since the arteries also can be readily 

 affected by pressure, it follows that gangrene of the 

 limb, as a result of improper treatment, is more com- 

 mon after fracture of the fore-arm than after fracture 

 in any other part. 



Amputation of the fore-arm. In amputa- 

 tion of the fore-arm by double transfixion flaps, at 

 about the upper part of ,the middle third the parts 

 would be cut in the following manner : On the face of 

 the anterior flap would be seen from without inwards 



R 4 



