THE RADIAL ARTERY. 787 



teres. This is often indicated by a yellowish (cellulo-fatty) line. The fibres of the 

 former muscle are almost parallel with the long axis of the forearm and overlie the 

 artery ; those of the latter are oblique and lie close to the inner side of the vessel. 

 The nerve is so far external that it is not likely to be seen. The artery, with its 

 vense comites, lies on the supinator brevis. 



2. At the middle of the forearm the incision is made on the same line. The 

 same relations exist, except that there the nerve is usually very near to the outer side 

 of the artery, which now lies on the tendon of insertion of the pronator radii teres. 



As the brachio-radialis is not very wide at this part (especially if the artery is 

 sought for at the lower end of the middle third), it is very easy to expose the outer 

 instead of the inner border of the muscle, in which case the muscle is apt to be drawn 

 inward, and when the depths of the wound are opened up the radial nerve is reached. 

 This is the common error of beginners. 



The tendon of the brachio-radialis, as a rule, first makes its appearance at the 

 outer border of the muscle, so that if this tendinous edge is exposed the operator 

 will know that he has laid bare the wrong side of the muscle. The inner border 

 of the latter remains muscular, until it ends somewhat abruptly in the tendon 

 (Treves). * 



3. At the lorver third the incision should be m.ade midway between the tendon 

 of the brachio-radialis and that of the flexor carpi radialis, the latter of which may 

 be made prominent by strongly extending the hand. The vessel is very superficial, 

 and is disclosed as soon as the thin fascia is divided. The nerve has left the 

 vessel altogether (at a level of from three inches above the wrist to the middle 

 of the forearm) and has passed under the brachio-radialis tendon to the dorsum 

 of the hand. 



4. In the triangular fossa between the lower end of the radius and the root of the 

 thumb {Jabatiere anatomique), bounded externally by the tendon of the extensor 

 longus poUicis, internally by the tendons of the extensor brevis pollicis and the 

 extensor ossis metacarpi pollicis, and superiorly by the inferior margin of the posterior 

 annular ligament (Fig. 716), the radial artery may occasionally require ligation on 

 account of wound or of aneurism. An incision one inch and a half long should be 

 made obliquely across the fossa, observing to avoid one of the chief radicles of the 

 radial vein, which lies in the superficial fascia immediately In the course of the wound. 

 After opening the fascia, and displacing some loose adipose tissue, the artery will be 

 reached at the bottom of the depression between the tendons of the thumb. It is 

 desirable to avoid opening the sheaths of the tendons or the joint between the scaph- 

 oid and trapezium ; these bones together with the base of the first metacarpal form 

 the floor of the space. 



The collateral circulation after ligation of the radial is carried on as after ligation 

 of the ulnar, q. v. 



Wounds of a palmar or carpal arch are apt to be troublesome on account of the 

 occasional difficulty in finding and securing both ends of the divided v^essel, and 

 because of the very free anastomosis between the palmar and carpal arches and the 

 interosseous vessels, which leads to recurrent hemorrhage, even after ligation of both 

 radial and ulnar. Compression over the wound, firm bandaging from the finger-tips 

 to the axilla, and elevation of the limb, are, for these reasons, the methods usually 

 first employed, and if applied thoroughly will generally be effectual. Ligation of the 

 brachial is indicated when these have failed, on account of the necessity for getting 

 above the interosseous anastomotic supply {vide S7ipra). 



I. The Radial Recurrent Artery. — The radial recurrent (a. recurrens radialis) 

 (Fig. 712) arises from the outer surface of the radial, shortly below its origin. It is 

 at first directed downward upon the surface of the supinator brevis, but quickly 

 bends upward towards the external condyle of the humerus, passing between the 

 radial and posterior interosseous nerves and lying beneath the supinator longus. 

 It gives numerous branches to the supinator longus and brevis and to the extensor 

 carpi radialis longior and the extensor carpi radialis brevior, and terminates at the 

 external condyle by anastomosing with the superior profunda from the brachial 

 artery. 



