78o 



HUMAN ANATOMY. 



a persistent median or interosseous artery, — a condition of which indications are to be seen in 

 the participation of the interosseous or median artery in the formation of the superficial palmar 

 arch (page 785). An interesting condition in which indications are clearly retained of all the 

 stages which the forearm arteries pass through in their evolution is shown in Fig. 711. An 

 artery which is the superficial brachial, and which arose from the axillary, descends the arm 

 parallel to the brachial proper and terminates by becoming the radial. A distinct ulnar has 

 developed and the anterior interosseous has acquired its typical arrangement, but there is a 

 well-developed median artery which sends a strong branch across to the radial and termi- 

 nates by anastomosing with the superficial palmar branch of the ulnar to form the superficial 

 palmar arch. 



Another variation may occur in the form of a "high origin" of the ulnar artery, a condi- 

 tion which results from the anastomosis of the superficial brachial artery (page 774) with the 

 ulnar. In such cases the ulnar frequently passes down the forearm in a much more superficial 



position than usual, passing over, instead, of under, 

 the muscles arising from the internal condyle. 

 Such a superficial course may also be followed when 

 the artery has a normal origin, and occasionally 

 it passes to the ulnar border of the forearm be- 

 tween the palmaris longus and the flexor sublimis 

 digitorum. 



Fig. 711. 



Brachial 



Superficial 

 brachial 



Ulnar 



Median 



Superficial 

 palmar 

 arch 



Anterior 

 interosseous 



Variation of arteries of left arm, showing 

 retention of developmental conditions. 



Practical Considerations. — The ul- 

 nar artery may be ligated for wound or for 

 aneurism — of which it is rarely the subject — 

 either ( i ) about the middle of the forearm or 

 (2) just above the wrist. 



I. With the forearm supinated, an in- 

 cision on the line indicated (^vide supra) 

 through the skin and the thin deep fascia 

 should expose either a white line — the ten- 

 dinous edge of the flexor carpi ulnaris — which 

 is not always present (Treves), or a yellow 

 (fatty) interspace (Farabeuf) between that 

 muscle and the flexor sublimis digitorum. It 

 is best marked at the lower part of the wound. 

 If more than one white line should be present, 

 the one sought for would be nearer the ulnar 

 margin of the limb. At the bottom of the 

 interspace thus identified, which runs oblique- 

 ly inward towards the ulna, the artery will be 

 found lying on the flexor profundus digitorum, 

 with the ulnar nerve to its inner side. It 

 is often overlapped by the inner deep edge 

 of the flexor sublimis, so that that muscle 

 must be lifted up and drawn outward before 

 the vessel can be fully exposed. In sepa- 

 rating the muscles care must be taken not to 

 go beyond the vessel and nerve — pushing 

 them to the radial side — and open up the in- 

 terspace between the flexor carpi ulnaris and 

 the flexor profundus. The space between 

 the flexor sublimis and the palmaris longus 

 of the proper space, but is much more shallow and even 



Deep 



palmar 

 arch 



lies to the outer side 

 less well marked. 



2. Forcibly extend the hand so as to bring into prominence the fleshy swell of 

 the flexor sublimis muscle and tendons, just to the ulnar side of the palmaris longus 

 (page 620). The incision, beginning about one inch above the flexure of the wrist, 

 should be made in the groove to the inner side of this prominence, and is immedi- 

 ately in line with the pisiform bone. After the deep fascia is divided the tendon of 

 the flexor carpi ulnaris is seen and, after it is relaxed by flexion of the wrist, is drawn 

 a little inward, when the artery will be found still lying upon the flexor profundus 

 and bound to it by a definite layer of fascia, which must be carefully divided 

 (Treves). The ulnar nerve lies in close proximity to the vessel on the ulnar side. 



