THE RADIAL ARTERY 265 



arch with the posteroarticular under the triceps. This artery 

 forms anastomoses with all the vessels around the elbow, 

 excepting only the radial recurrent. 



The brachial divides, about J inch below the elbow, into the 

 radial and ulnar arteries. 



The antecubital space or fossa is situated at the bend of the 

 elbow. It is triangular in shape, the base corresponds to a line 

 drawn between the internal and external condyles of the 

 humerus; externally, the inner border of the brachioradialis or 

 supinator longus; internally, the inner border of the pronator 

 radii teres; its floor is covered by the supinator brevis and 

 brachialis anticus, and tendon of insertion of the biceps brachii ; 

 it is enclosed by the deep fascia, a part of the bicipital fascia, 

 superficial fascia, and the integument. It contains the brachial, 

 radial, and ulnar arteries, and accompanying veins; the median 

 and musculospiral nerves. The median basilic vein is sepa- 

 rated from the brachial artery by the deep fascia of the 

 forearm, and the bicipital fascia beneath the latter. 



The Radial Artery 



The radial artery runs from the bifurcation of the brachial 

 along the radial side of the forearm to the wrist, and winds back 

 to its posterior surface. It then enters the palm through the 

 first dorsal interosseous, and runs across the hand to form the 

 deep palmar arch by joining the deep branch of the ulnar. 



In the Forearm. Relations. In front, integument, fascia, and 

 supinator longus overlapping it; behind, from above downward, 

 it lies on the tendon of the biceps, supinator brevis, pronator 

 teres, flexor sublimis, flexor longus pollicis, pronator quadratus, 

 and radius; on the ulnar side, flexor carpi radialis and pronator 

 teres; on the radial side, supinator longus and radial nerve 

 (its middle third). 



In the wrist it lies on the external lateral ligament, scaphoid, 

 and trapezium, and is covered by the extensors of the thumb, 

 cutaneous veins, and by filaments of the radial and musculo- 

 cutaneous nerves. 



In the hand it lies on the metacarpal bones and interossei, 

 covered by the flexor tendons^ opponens, flexor brevis minimi 

 digiti, and flexor brevis pollicis. 



