VI nar Artery 277 



interosseous muscle (abductor indicis), and lies, therefore, very deeply 

 beneath the tendons of the flexor profundus and the lumbricals. 



Its position on tJie surface may be marked by a transverse line an 

 inch nearer to the wrist than that which shows the situation of the 

 superficial palmar arch. 



Branches. The princeps pollicis descends between the abductor 

 indicis and adductor pollicis, and at the base of the first phalanx- 

 divides to supply the sides of the thumb. 



The radialis indicis descends" between the same muscles to the 

 radial side of the index-finger, at the tip of which it anastomoses with 

 the outermost digital branch of the ulnar to complete the superficial 

 palmar arch. 



Perforating; branches pass between the heads of the three inner 

 dorsal interosseous muscles to join the dorsal interosseous arteries, 

 and three palmar interosseous twigs descend to the clefts of the 

 fingers to communicate with the digital branches of the ulnar. 



The ulnar artery is the larger division of the brachial, and, 

 beginning at the middle of the bend of the elbow, eventually reaches 

 the palm under the protection of the pisiform bone, to the radial side 

 of which it lies as it descends over the annular ligament. 



To mark the course of the artery in the fore-arm, a slightly curved 

 line, with the convexity inwards, is drawn from the inner side of the 

 tendon of the biceps to a little above the middle of the fore-arm, and 

 from that spot, straight down the radial border of the flexor carpi 

 ulnaris, to the outer side of the pisiform. 



In the curved part of its course the ulnar artery is burrowing 

 deeply beneath the pronator radii teres and company, and is occupy- 

 ing a position of more interest to the anatomist than the surgeon. 

 The surgeon does not attempt to reach the artery by cutting across 

 those muscles, but prefers to wait for it until it is approaching the 

 inner border of the upper part of the fore-arm. 



Relations. T\& guide to the artery is the flexor carpi ulnaris, but, 

 as just remarked, in the beginning of its course the artery is separated 

 from it by the group of muscles arising from the internal condyle, 

 namely, the pronator teres, flexor radialis, palmaris longus, and flexor 

 sublimis. To reach the flexor carpi ulnaris the artery does not pass 

 over this group, or it would be dangerously superficial, and it cannot 

 pass through it, so it passes beneath it. As it dips beneath the deep 

 head of the pronator teres the median nerve is passing between the 

 two heads of that muscle, therefore the median nerve is an additional 

 superficial relation to the beginning of the artery. 



The manner in which the median nerve crosses the ulnar artery is 

 clear to the student when he traces on the surface of the fore-arm the 

 boundaries of the triangle, and places in their proper position the 

 tendon of the biceps, the brachial artery, and the median nerve. If 

 the line of the median nerve be then prolonged to the inner side of 



