ULNAR 531 



THF ULNAE ARTERY 



The ulnar artery, the larger of the two ternimal })ranches of the brachial, 

 begins opposite the lower border of the head of the radius in the middle line of the 

 forearm. Tlienee through the upper half of the forearm it runs in a slight curve, 

 with its convexity inwards, deeply beneath the pronator teres and superficial 

 flexor muscles, and, having reached the ulnar side of the limb about midway 

 l)etween the elbow and the wrist, it passes directly doAvnwards, being merely over- 

 lapped by the flexor carpi ulnaris. Crossing the annular ligament immediately to 

 the radial side of the pisiform bone, it enters the palm, where it divides into two 

 branches, which enter respectively into the formation of the superficial and deep 

 palmar arches. The artery is accompanied by two veins, which anastomose with 

 each other by frequent cross l^ranches, and usually terminate in the l>rachial vense 

 comites; or sometimes the inner vena comes ends in the inner brachial vein, the 

 outer vena comes in the median profunda vein. The ulnar nerve is at first some 

 distance from the artery, but approaches the vessel at the junction (^f its upj^er and 

 middle thirds, and then lies close to its inner or ulnar side. The course of the 

 artery in the lower two-thirds of the forearm is indicated by a line drawn from the 

 front of the internal condyle to the radial side of the pisiform bone; and in the 

 upper third of the forearm by a line drawn in a gentle curve with its convexity 

 inwards from an inch below the centre of the bend of the elbow to a point in the 

 former line at the junction of its upper with its middle third. The artery through- 

 out its course is best reached through the innermost intermuscular septum, i.e. the 

 interval between the flexor carpi ulnaris and the flexor sublimis digitorum. 



The relations of the artery will be given in detail — as it lies in the forearm, at 

 the wrist, and in the palm of the hand. 



I. Relations of the Ulnar Artery in the Forearm 



In front. — In the upper half of the forearm the ulnar artery is deei)ly i)Iaced 

 beneath the pronator teres, the flexor carpi radialis, the palmaris longus, and the 

 flexor sublimis digitorum. In the lower half it is comparatively superficial, Ijeing 

 merely overla])})ed above by the tendon of the flexor carjji ulnaris, whilst the last 

 inch or so of the vessel is only covered as a rule by the skin and superficial and 

 deep fasciae. As the artery lies beneath the pronator teres, it is crossed from 

 within outwards by the mediari nerve, the deep head of origin of the muscle 

 usually separating the nerve from the artery. The lower part of the artery is 

 crossed by the ])almar cutaneous branch of the ulnar nerve. 



Behind. — For about an inch of its course the artery lies upon the liracliialis 

 antirus; l)ut thence, as far as the anterior annular ligament of the wrist, u})on the 

 flexor profundus digitorum, which separates it above from the interosseous mem- 

 brane and bone, and at the wrist from the pronator quadra tus. The artery is 

 bound down to the flexor profundus digitorum by bands of fasciae. 



To the outer side in the lower two-thirds of its course is the flexor sublimis 

 digitorum. 



To the inner side in the lower two-thirds is the flexor carj»i uhiaris. the guiile 

 to the vessel. The ulnar nerve, as it enters the forearm from behind the inner 

 condyle, is at first some distance from the artery, being sejiarated from it in its 

 upper third l)y the flexor sul)limis digitorum, but in its lower two-thirds is in close 

 contact with the vessel and on its ulnar side. 



Variations of the llnar Artcrj/ in the Forearm 



Tlio principal variations of the ulnar artery in the forearm are : (A) It may arise from the 

 brachial alxivc the usual ]i(iiiit of division or from the axillary, in wliicli casi- it usually lains over 

 the flexor muscles, but beneath the fascia, to reach its usual situation in the forearm. Tlie recur- 

 rent arteries and the common iuterosseou.s are then usually derived fnnu the trunk ves.sel from 



