302 



APPLIED ANATOMY. 



In raising the supinator (brevis) from the upper portion of the radius care 

 should be exercised not to wound the posterior interosseous nerve. It runs between 

 two planes of muscular fibres in the substance of the supinator (brevis). It is a 

 nerve of motion supplying all the extensor muscles with the exception of the anco- 

 neus, brachioradialis (supinator longus), and extensor carpi radialis longior; hence 

 its injury will be followed by serious paralysis. Almost no vessels require ligation 

 (Fig. 316). 



AMPUTATION AT THE ELBOW-JOINT. 



Amputation at this joint is peculiar from the fact of the width of the lower end of 

 the humerus. The skin is loose and shows a marked tendency to retract, especially on 

 the anterior surface. This, combined with the large, expanded end of the humerus, 



Tendon of biceps 



Radial (musculospiral) 



nerve, superficial and 



deep branches 



Stump of extensor and 

 supinator muscles 



Radial artery 



Internal (antibrachii 

 medialis) cutaneous 

 nerve 



Median nerve 

 Ulnar artery 



Ulnar nerve 



ump of flexor muscles 



FIG. 317. Amputation at the elbow- joint. 



requires ample flaps to be made or difficulty will be encountered in properly covering 

 the end of the humerus. The irregularity of the line of the joint makes disarticula- 

 tion somewhat difficult (Fig. 317). 



A long anterior flap with or without a short posterior one is usually advised. 

 On account of the tendency to retraction the ends of the incision are not carried up 

 to the condyles but are kept at least 2. 5 cm. ( i in. ) below them. 



If the flap is cut by transfixion the line of the articulation must be borne in mind. 

 Inasmuch as the trochlear surface projects farther down than the capitellum it is 

 customary to incline the knife downward and inward. Also, as the trochlear portion 

 is thicker, wider, and projects farther than the capitellum, the inner side of the flap is 

 made longer than the outer. 



The skin on the anterior surface is loose and retracts freely as soon as cut ; hence 

 the muscles are often cut by transfixion. The skin on the posterior surface is not so 

 loose and does not exhibit the same tendency to retraction. After the anterior 

 muscles have been raised and the short posterior skin flap turned back the joint is to 



