THE ULNAR ARTERY 651 



PLAN OF RELATIONS OF THE ULN/R ARTERY IN THE FOREARM. 



In front. 



TT TT if \ Superficial layer of Flexor muscles. 

 Upper Half | Median nenr ^ 



Lower Half Superficial and deep fasciae. 



Inner side. 



Outer side. 



Flexor carpi ulnaris. 



Ulnar nerve (lower two-thirds). V Forearm - I Flexor subhmis digitorum. 



Behind. 



Brachialis anticus. 



Flexor profundus digitorum. 



At the wrist (Fig. 462) the ulnar artery is covered by the integument and fascia, and lies 

 upon the anterior annular ligament. On its inner side is the pisiform bone, and somewhat 

 behind the artery, the ulnar nerve. The nerve and artery are crossed by a band of fibres, which 

 extends from the pisiform bone to the anterior annular ligament. 



Peculiarities. The ulnar artery has been found to vary in its origin nearly in the propor- 

 tion of one in thirteen cases, in one case arising lower than usual, about two or three inches 

 below the elbow, and in all other cases much higher, the brachial being a more frequent source 

 of origin than the axillary. 



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 in- 

 variably 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 

 surface 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 antecubital space to the junction of the 

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

 artery. 



Applied 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 fore- 

 arm the artery is deeply seated beneath the Superficial Flexor muscles, and the application 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 venae 

 comites, and it may be ligated 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. 



