412 ARTERIES. 



divided, and the Supinator longus drawn a little outwards, the artery will be exposed. The 

 venae comites should be carefully separated from the vessel, and the ligature passed from the 

 radial to the ulnar side. 



In the middle third of the forearm the artery may be exposed by making an incision of similar 

 length on the inner margin of the Supinator longus. In this situation the radial nerve lies 

 in close relation with the outer side of the artery, and should, as well as the veins, be carefully 

 avoided. 



In the lower third, the artery is easily secured by dividing the integument and fasciae in the 

 interval between the tendons of the Supinator Longus and Flexor carpi radialis muscles. 



The branches of the radial artery may be divided into three groups, correspond- 

 ing with the three regions in which this vessel is situated. 



( Radial recurrent. f Posterior carpal. 



In the j Muscular. W ' t ' Metacarpal. 



Forearm. 1 Superficialis vola3. LS ' 1 Dorsales pollicis, 



[ Anterior carpal. [ Dorsalis indicis. 



f Princeps pollicis. 



TT i Radialis indicis. 

 nana. -< TJ j, 



Perforantes. 



Interossese. 



The radial recurrent is given off' immediately below the elbow. It ascends 

 between the branches of the musculo-spiral nerve, lying on the Supinator brevis, 

 and then between the Supinator longus and Brachialis anticus, supplying these 

 muscles, the elbow-joint, and anastomosing with the terminal branches of the 

 superior profunda. 



The muscular branches are distributed to the muscles on the radial side of the 

 forearm. 



The superficialis volse arises from the radial artery, just where this vessel is 

 about to wind round the wrist. Running forwards, it passes between the muscles 

 of the thumb, which it supplies, and anastomoses with the termination of the ulnar 

 artery, completing the superficial palmar arch. This vessel varies considerably 

 in size, usually being very small, and terminating in the muscles of the thumb ; 

 sometimes it is as large as the continuation of the radial. 



The carpal branches supply the joints of the wrist. The anterior carpal is a 

 small vessel which arises from the radial artery near the lower border of the Pro- 

 nator quadratus, and, running inwards in front of the radius, anastomoses with the 

 anterior carpal branch of the ulnar artery. From the arch thus formed, branches 

 descend to supply the articulations of the wrist. 



The posterior carpal is a small vessel which arises from the radial artery beneath 

 the Extensor tendons of the thumb ; crossing the carpus transversely to the inner 

 border of the hand, it anastomoses with the posterior carpal branch of the ulnar. 

 It sends branches upwards, which anastomose with the termination of the ante- 

 rior interosseous artery ; other branches descend to the metacarpal spaces ; they 

 are the dorsal interosseous arteries for the third and fourth interosseous spaces, 

 and anastomose with the posterior perforating branches from the deep palmar 

 arch. 



The metacarpal (first dorsal interosseous branch) arises beneath the Extensor 

 tendons of the thumb, sometimes with the posterior carpal artery, running for- 

 wards on the second Dorsal interosseous muscle; communicating, behind, with 

 the corresponding perforating branch of the deep palmar arch; and, in front, 

 inosculating with the digital branch of the superficial palmar arch, and supplying 

 the adjoining sides of the index and middle fingers. 



The dorsaks pollicis are two small vessels which run along the sides of the 

 dorsal aspect of the thumb. They sometimes arise separately, or occasionally by 

 a common trunk, near the base of the first metacarpal bone. 



The dorsalis indicis, also a small branch, runs along the radial side of the back 

 of the index finger, sending a few branches to the Abductor indicis. 



