276 The Arteries of the Fore-ami 



on the insertion of the pronator radii teres. The radial nerve will 

 probably not yet have joined company with the artery, or it may be 

 approaching it from the outer side, deeply hidden beneath the supi- 

 nator. The needle should be passed from the outer side, so as to 

 make sure of not taking up the nerve. 



In the middle third of the fore-arm an incision made in the course 

 of the artery falls to the inner side of the supinator, and exposes the 

 vessel in the interval between that muscle and the flexor carpi radialis. 

 The artery is still between its venae comites, with the nerve close 

 on the outer side. From that side, therefore, the needle should be 

 passed. 



Near the wrist the artery is quite superficial, lying along the 

 middle of the hollow between the tendons of the flexor carpi radialis 

 and supinator longus ; the latter, however, can hardly be made out as 

 it is approaching its insertion into the styloid process. A two-inch in- 

 cision being made through the thin skin and superficial fascia, the 

 deep fascia is divided on a director, and the artery is at once exposed, 

 together with its venae comites. The nerve has long since left the artery 

 to pass beneath the supinator longus towards the back of the hand 

 and fingers. 



At the outer side of the wrist, the radial artery winds beneath 

 the extensor tendons of the thumb, over the external lateral ligament, 

 and over the scaphoid and trapezium. It lies beneath the integument 

 and fascia?, and beneath branches of the radial vein and of the radial 

 and musculo-cutaneous nerves in the hollow (often called the an<ilo- 

 misfs snuff-box), which is bounded above by the styloid process, below 

 by the root of the first metacarpal bone, externally by the prominent 

 tendons of the extensors ossis and primi, and internally by the oblique 

 tendon of the secundi. The course of the artery is shown by a line from 

 the tip of the radial styloid process to the inner side of the base of the 

 metacarpal bone of the thumb. The vessel is rather deeply placed. 



The branches given off here are posterior carpal, the first dorsal 

 interosseous, or metacarpal, the dorsales pollicis, and the dorsal is 

 indicis. They are all small branches, and their courses are suffi- 

 ciently indicated by their names. The first dorsal interosseous artery, 

 like the others, is joined at the root of the space by a perforating 

 branch of the deep palmar arch, and at the cleft it turns forward to 

 communicate with the digital branch of the superficial arch. 



Ligation maybe performed by a I \ in. incision downwards from 

 the styloid process ; branches of the radial vein and nerve are divided 

 with the superficial fascia. The artery is found between its com- 

 panion veins. The vessel is somewhat deep and inaccessible in this 

 hollow, and the operation for its ligation there is not so desirable as at 

 the front of the wrist. 



In th palm, the radial artery crosses the roots of the mc-ta- 

 iarpal bones; it has entered between the heads of the first dorsal 



