i6 



external flexors of the carpus and to the artery and vein. Five to eight 

 centimeters from the carpus the nerve divides into two branches of which 

 one pierces the aponeurosis and passes, subcutaneously, across the tendon 

 of the flexor carpi extemus and divides into numerous branches which extend 

 obliquely to the antero-lateral face of the carpus and metacarpus (PI. Ill, 

 25'; PI. II, 26). The other terminal branch of the N. ulnaris unites with a 

 branch of the N. medianus, below the supracarpal arch, and thus forms the 

 N. volaris lateralis (PI. Ill, 26). 



A. radialis anterior (PL II, 19) is the smaller of the two terminal branches 

 of the A. brachialis. It passes obliquely downward and outward between 

 the anterior face of the humerus and the Mm. biceps brachii and the 

 brachialis. Transect the brachialis where it crosses the external surface of 

 the tendon of the biceps. Beneath the brachialis and the extensor carpi 

 radialis, the artery supplies branches to these muscles. Beneath the exten- 

 sor digitalis communis the A. radialis anterior gives off two or three small 

 branches to this muscle; it also sends a branch to the extensor digitalis 

 lateralis and to the flexor carpi extemus. The A. radialis anterior is 

 continued as a small branch which extends along the antero-intemal 

 aspect of the radius to the carpus where it joins the rete carpi dorsalis. 



A. radialis posterior (PI. I, 26) is the direct continuation of the A. brachialis 

 and is the larger of its two terminal branches. The artery crosses the 

 antero-intemal face of the himiero-radial joint and is here covered by 

 the skin, the aponeurosis and the posterior superficial pectoral muscle. 

 Note that in this region the N. medianus, as it passes from the posterior 

 to the anterior side of the artery and vein, lies superficially to the blood- 

 vessels (PI. I). A little below the humero-radial joint the A. radialis 

 posterior, accompanied by the N. medianus, passes under the flexor carpi 

 internus (PI. I, 16) which should be transected and turned aside. Beneath 

 this muscle it extends to the distal third of the shaft of the radius and is then 

 continued by the large A. digitalis communis and the two metacarpal 

 arteries. 



Branches of the A. radialis posterior. 



(i) One or more small branches to the humero-radial joint. 



(2) Muscular branches to the flexor carpi internus and medius and 

 to the flexor perfortus and perforans. 



(3) A. interossea communis, is a large branch that arises from the 

 radialis posterior near the level of the radio-iilnar arch through which the 

 interossea communis passes. In the interosseous space it gives off the 

 nutrient artery of -the radius. After passing through the interosseus space 



