THE ULXAR ARTERY. 601 



of the last phalanx, from which branches are distributed to the integument and 

 pulp of the thumb. 



The radialis indicis arises close to the preceding, descends between the 

 Abductor indicis and Adductor transversus pollicis. and runs along the radial 

 side of the index finger to its extremity, where it anastomoses with the collateral 

 digital artery from the superficial palmar arch. At the lower border of the 

 Adductor transversus pollicis this vessel anastomoses with the princeps pollicis, 

 and gives a communicating branch to the superficial palmar arch. 



The superior perforating arteries, three in number, pass backward between the 

 heads of the last three Dorsal interossei muscles, to inosculate with the dorsal 

 interosseous arteries. 



The palmar interosseous, three or four in number, are branches of the deep 

 palmar arch : they run forward upon the Interossei muscles, and anastomose at 

 the clefts of the fingers with the digital branches of the superficial arch. 



The palmar recurrent branches arise from the concavity of the deep palmar 

 arch. They pass upward in front of the wrist, supplying the carpal articulations 

 and anastomosing with the anterior carpal arch. 



Ulnar Artery. 



The Ulnar Artery, the larger of the two terminal branches of the brachial, 

 commences a little below the bend of the elbow, and crosses obliquely the inner 

 side of the forearm, to the commencement of its lower half; it then runs along its 

 ulnar border to the wrist, crosses the annular ligament on the radial side of the 

 pisiform bone, and immediately beyond this bone divides into two branches, 

 superficial and deep palmar. 



Relations in the Forearm. In its upper half it is deeply seated, being covered 

 by all the superficial flexor muscles, excepting the Flexor carpi ulnaris ; it is 

 crossed by the median nerve (deep head of Pronator radii teres intervening), 

 which lies just above to its inner side, and it lies upon the Brachialis 

 anticus and Flexor profundus digitorum muscles. In the lower half of 

 the forearm it lies upon the Flexor profundus, being covered by the integu- 

 ment, the superficial and deep fasciae, and is placed between the Flexor 

 carpi ulnaris and Flexor sublimis digitorum muscles. It is accompanied 

 by two venae comites ; the ulnar nerve lies on its inner side for the lower two- 

 thirds of its extent, and a small branch from the nerve descends on the lower part 

 of the vessel to the palm of the hand. 



PLAN OF RELATIONS OF THE ULNAR ARTERY IN THE FOREARM. 



In front. 



fl^ifnter^ 61 " f ** "^ } U PP half ' 

 Superficial and deep fasciae. Lower half. 



Lu.fr Me. , ,,.. Outer Me, 



Behind. 



Brachialis anticus. 

 Flexor profundus digitorum. 



At the wrist (Fig. 364) 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. The ulnar nerve lies at the inner side, and somewhat behind the 

 artery. 



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. 



