VARIETIES OF THE ARTERIES OF THE HAND. 



453 



before mentioned, be reinforced from other vessels, viz., from the superficial volar, from an 

 enlarged median artery, or from a large dorsal interosseous branch. 



It sometimes, but less frequently, happens that the deep system of vessels is deficient, in 

 which case the superficial arch may supply all the digital arteries to the thumb and fingers, 



Fig. 369. AN ENLARGED MEDIAN ARTERY REPLACING THE RADIAL 



AND ULNAR IN THE SUPPLY OP PALMAR ARTERIES TO HALF 



THE DIGITS. (Tiedemann.) $ 



1, lower part of brachial artery; 2, radial artery, not giving 

 any superficial volar branch ; 3, recurrent radial ; 4, ulnar artery, 

 passing over the wrist and supplying at 4', 4', 4', digital arteries 

 to half the hand ; 5, the enlarged median artery, passing in front 

 of the annular ligament of the wrist and supplying 5', 5', digital 

 branches to the outer half of the hand. 



or one or more of these may be derived from the superficial 

 volar, the median, or a dorsal interosseous artery. 



The superficial palmar arch has occasionally been seen 

 double, the superficial part of the ulnar artery and the 

 superficial volar branch of the radial being each divided 

 into two communicating branches. Two of the digital 

 arteries frequently arise by a common trunk. 



SURGICAL ANATOMY OF THE ULNAR AND 

 RADIAL ARTERIES. 



In the upper third of the forearm, the depth at which 

 the ulnar artery is placed beneath the muscles, and the 

 origin of the large interosseous branch prevent the appli- 

 cation of a ligature to this part of the vessel. 



In the middle third, the artery may be tied as it ap- 

 proaches the ulnar nerve. An incision is made along a line 

 drawn from the internal condyle of the humerus to the 

 pisiform bone, and the intermuscular space between the 

 flexor sublimis digitorum and flexor carpi ulnaris opened 

 up, when the ulnar nerve comes into view. The artery, 

 accompanied by its v^nse comites, will be found to the outer 

 side of the nerve, a little way removed from it, and under 

 cover of the flexor sublimis digitorum, if the spot selected be 

 above the middle of the forearm. 



Near the wrist, the artery is readily exposed by an 

 incision along the outer border of the flexor carpi ulnaris 

 tendon. After drawing inwards this tendon, a deep layer of 

 fascia is seen covering the vessels, and on dividing this the 

 artery is laid bare with the nerve to its inner side. 



The radial artery may be ligatured in any part of its 

 extent in the forearm by means of an incision carried 



through the skin and fascia in the course of the vessel, i.e., along a line from the centre 

 of the bend of the elbow to the fore part of the styloid process of the radius. In the upper 

 half of the forearm, the fleshy belly of the supinator longus will have to be drawn 

 outwards ; in the lower half, the artery lies close to the outer side of the tendon of the 

 flexor carpi radialis, which forms a guide to the vessel. When exposing the radial artery near 

 the wrist its superficial position must be borne in mind, and the first incision should divide 

 only the skin and fat. 



At the wrist, the radial artery may also be readily secured, the incision being made midway 

 between the tendons of the extensor ossis metacarpi and longus pollicis. The radial vein is at 

 once exposed, and must not be mistaken for the artery, which is much deeper and lies 

 obliquely to the line of the incision. It is generally preferable, however, to tie the artery at 

 the lower part of the forearm. 



Collateral circulation. The communications between the branches of the ulnar and radial 

 arteries, about the wrist and in the palm, are so numerous and free that the circulation in 

 the hand is carried on without difficulty after occlusion of either of the main trunks. 



It is important to bear in mind, in connection with wounds of the palmar arteries, the 

 possibility of blood being conveyed to the hand by other channels than the ulnar and radial 

 trunks, viz., by a large median artery, or a terminal branch of the anterior interosseous. 



G a 2 



