80 TOPOGRAPHIC AND APPLIED ANATOMY. 



FIG. 33. The region of the elbow. (The radial nerve has been drawn up from the depths and made to assume a more 



superficial position.) 



pierces the deep fascia in the external bicipital groove to the inner side of the cephalic vein, 

 passes partly over and partly under the median cubital vein (or median cephalic vein), and runs 

 downward to the wrist. At the bend of the elbow there is a constant and marked anastomosis 

 between the median cubital vein and the deep veins of this region. 



Removing the deep fascia and leaving the bicipital fascia behind, we obtain a view of the 

 lower boundary of this region, which is formed upon the ulnar side by the edge of the pronator 

 radii teres muscle, and upon the radial side by the inner border of the supinator longus muscle. 

 The brachial artery is easily exposed. At the lower end of the internal bicipital groove it passes 

 beneath the bicipital fascia, lies to the inner side of the bicipital tendon, and divides in front of the 

 tendon of the brachialis anticus into its two terminal branches, the radial artery and the ulnar 

 artery. The artery is accompanied by venae comites. In this situation it is separated from the 

 median cubital vein by nothing but the deep and bicipital fasciae, and should consequently be 

 carefully avoided in phlebotomy or transfusion into the vein. In the ligation of the artery care 

 should also be taken to avoid unnecessary injury to the median cubital vein, which should be 

 pushed to one side. If the incision is made too far to the inner side, the median nerve will be 

 exposed, and the artery is consequently to be sought for to the outer side of the wound. In this 

 region the brachial artery gives off no special branches, but vessels are given off almost immediately 

 by its two terminal divisions. The relative position of these terminal divisions is best demon- 

 strated by a sagittal frozen section (see Fig. 34), which shows that the radial is at first more 

 superficial than the ulnar artery. In the bend of the elbow the radial artery gives off the radial 

 recurrent, which ascends upon the supinator brevis muscle toward the musculospiral nerve to 

 supply the rete articulare cubiti. The ulnar artery also assists in the formation of this articular 

 anastomosis by giving off the anterior and posterior recurrent branches which frequently arise by 

 a common trunk. The anterior ulnar recurrent artery anastomoses with the anastomotica 

 magna from the brachial; the posterior ulnar recurrent artery passes upward in the groove 

 between the olecranon and the internal condyle and anastomoses with the inferior profunda from 

 the brachial. 



A knowledge of the relations of the three main nerves of the arm is important for all opera- 

 tive procedures in the neighborhood of the elbow-joint. The median nerve, the motor nerve for 

 all of the flexor muscles of the forearm (except the flexor carpi ulnaris and the ulnar half of the 

 flexor profundus digitorum), is situated beneath the bicipital fascia to the inner side of the bra- 

 chial artery. This nerve reaches the forearm by piercing the pronator radii teres, but gives off 

 some muscular branches before entering this muscle. The ulnar nerve is to be found upon the 

 extensor surface alongside of the olecranon (see page 78). In this situation the ulnar nerve is to 

 be particularly avoided in the resection of the elbow-joint from behind. The nerve passes 

 between the origins of the flexor carpi ulnaris, coming from the internal epicondyle and from the 

 olecranon, reaches the deep surface of this muscle, which it supplies, and runs downward upon 

 the flexor side of the forearm. The musculospiral nerve is quite deeply situated in the outer 

 portion of the bend of the elbow, but may be easily exposed in the groove between the supinator 



