602 THE ARTERIES. 



Variations in the position of this vessel are more frequent than in the radial. When its 

 origin is normal the course of the vessel is rarely changed. When it arises high up it is almost 

 invariably superficial to the flexor muscles in the forearm, lying commonly beneath the fascia, 

 more rarely between the fascia and integument. In a few cases its position was subcutaneous 

 in the upper part of the forearm, subaponeurotic in the lower part. 



Surface Marking. On account of the curved direction of the ulnar artery the line on the sur- 

 face of the body which indicates its course is somewhat complicated. First, draw a line from the 

 front of the internal condyle of the humerus to the radial side of the pisiform bone ; the lower 

 two-thirds of this line represents the course of the middle and lower third of the ulnar artery. 

 Secondly, draw a line from the centre of the hollow in front of the elbow -joint to the junction of the 

 upper and middle third of the first line ; this represents the course of the upper third of the artery. 



Surgical Anatomy. The application of a ligature to this vessel is required in cases of 

 wound of the artery or of its branches, or in consequence of aneurism. In the upper half of 

 the forearm the artery is deeply seated beneath the superficial flexor muscles, and the applica- 

 tion of a ligature in this situation is attended with some difficulty. An incision is to be made 

 in the course of a line drawn from the front of the internal condyle of the humerus to the outer 

 side of the pisiform bone, so that the centre of the incision is three fingers' breadth below the 

 internal condyle. The skin and superficial fascia having been divided and the deep fascia 

 exposed, the white line which separates the Flexor carpi ulnaris from the other flexor muscles 

 is to be sought for, and the fascia incised in this line. The Flexor carpi ulnaris is now to be 

 carefully separated from the other muscles, when the ulnar nerve will be exposed, and must be 

 drawn aside. Some little distance below the nerve the artery will be found accompanied by its 

 vense comites, and may be ligatured by passing the needle from within outward. In the middle 

 and lower third of the forearm this vessel may be easily secured by making an incision on the 

 radial side of the tendon of the Flexor carpi ulnaris : the deep fascia being divided, and the 

 Flexor carpi ulnaris and its companion muscle, the Flexor sublimis, being separated from each 

 other, the vessel will be exposed, accompanied by its venae comites, the ulnar nerve lying on its 

 inner side. The veins being separated from the artery, the ligature should be passed from the 

 ulnar to the radial side, taking care to avoid the ulnar nerve. 



The branches of the ulnar artery may be arranged in the following groups : 



( Anterior Ulnar Recurrent. 

 Posterior Ulnar Recurrent. 



Forearm. f Anterior Interosseous. 



) Interosseous < -n T . 



\ Posterior Interosseous. 



^ Muscular. 

 Writ f Anterior Carpal. 



\ Posterior Carpal. 

 IT j / Superficial Palmar Arch. 



( Deep Palmar or Communicating. 



The anterior ulnar recurrent (Fig. 365) arises immediately below the elbow- 

 joint, passes upward and inward between the Brachialis anticus and Pronator 

 radii teres, supplies those muscles, and, in front of the inner condyle, anastomoses 

 with the anastomotica magna and inferior profunda. 



The posterior ulnar recurrent is much larger, and arises somewhat lower than 

 the preceding. It passes backward and inward, beneath the Flexor sublimis, 

 and ascends behind the inner condyle of the humerus. In the interval between 

 this process and the olecranon it lies beneath the Flexor carpi ulnaris, ascend- 

 ing between the heads of that muscle, beneath the ulnar nerve; it supplies the 

 neighboring muscles and joint, and anastomoses with the inferior profunda, anas- 

 tomotica magna, and interosseous recurrent arteries (Fig. 366). 



The interosseous artery (Fig. 365) is a short trunk about an inch in length, 

 and of considerable size, which arises immediately below the tuberosity of the 

 radius, and, passing backward to the upper border of the interosseous membrane, 

 divides into two branches, the anterior and posterior inter osseous. 



The anterior interosseous passes down the forearm on the anterior surface of 

 the interosseous membrane, to which it is connected, by a thin aponeurotic arch. 

 It is accompanied by the interosseous branch of the median nerve, and overlapped 

 by the contiguous margins of the Flexor profundus digitorum and Flexor longus 

 pollicis muscles, giving off in this situation muscular branches and the nutrient 

 arteries of the radius and ulna. At the upper border of the Pronator quadratus 

 a branch descends traaeath the muscle to anastomose in front of the carpus with 



