922 THE VASCULAE SYSTEM. 



the flexor digitorum profundus, and the transverse carpal ligament (O.T. anterior 

 annular). Volar. On its volar aspect it is crossed, in the oblique part of its course, 

 by the pronator teres, the median nerve, which is separated from the artery by the deep 

 head of the pronator teres, the flexor digitorum sublimis, the flexor carpi radialis, and the 

 palmaris longus. In the middle third of the forearm it is overlapped by the volar border 

 of the flexor carpi ulnaris, and in the distal third it is covered by skin and fasciae only. 

 A short distance proximal to the wrist the palmar cutaneous branch of the ulnar nerve lies 

 volar to it, and as it crosses the transverse carpal ligament, it is bound down by a fascial 

 expansion from the tendon of the flexor carpi ulnaris. Two vense comites, which 

 frequently communicate with one another, lie one on each side of the artery. On the 

 radial side there is also, in its distal two-thirds, the flexor digitorum sublimis. On its 

 ulnar side are the flexor carpi ulnaris and the ulnar nerve. 



Branches. (1) The volar ulnar recurrent is a small branch which arises in the 

 cubital fossa, frequently in common with the dorsal ulnar recurrent. It passes proximally, 

 to the anterior aspect of the medial epicondyle, under cover of the pronator teres, and 

 anastomoses with branches of the superior and inferior ulnar collateral arteries. 



(2) The dorsal ulnar recurrent branch, larger than the volar, arises in the cubital 

 fossa, from the ulnar side of the ulnar artery, and ascends, on the brachialis and under 

 cover of the muscles which arise from the medial epicondyle, to the posterior aspect of 

 that prominence, where it passes between the humeral and olecranoid heads of the flexor 

 carpi ulnaris, and anastomoses with the superior and inferior ulnar collateral arteries. It 

 gives branches to the adjacent muscles and to the elbow-joint. 



(3) The common interosseous artery, a short trunk which springs from the radial 

 and dorsal aspect of the ulnar artery, in the distal part of the cubital fossa. It passes 

 dorsally, towards the proximal border of the interosseous membrane, and divides into 

 volar and dorsal interosseous branches. 



(3a) The volar interosseous artery runs distally, on the volar surface of the 

 interosseous membrane, between the adjacent borders of the flexor pollicis longus and the 

 flexor digitorum profundus, to the proximal border of the pronator quadratus; there it 

 pierces the interosseous membrane, and continues distally, first on the dorsal surface of the 

 membrane, deep to the extensor pollicis longus and extensor indicis proprius, and then 

 on the dorsal surface of the radius, in the groove for the extensor digitorum commimis : 

 and it terminates, on the dorsum of the carpus,' by joining the dorsal carpal arch. It is 

 accompanied on the volar aspect of the interosseous membrane by the volar interosseous 

 nerve, and, after it has pierced the membrane, by the dorsal interosseous nerve. 



Branches. (a) Nutrient to the radius and ulna; (6) Muscular to the adjacent muscles; 

 (c) The volar communicating, a slender branch which passes distally, deep to the pronator 

 quadratus and on the volar surface of the interosseous membrane, to anastomose with the 

 volar carpal arch ; (<f) Small anastomotic branches are given off, on the dorsum of the forearm, to 

 anastomose with the dorsal interosseous artery ; (e) The median artery (O.T comes nervi mediani) 

 is a long slender branch which arises from the proximal part of the volar interosseous artery and 

 runs with the median nerve to the palm, where it anastomoses with recurrent branches of the 

 superficial volar arch. 



(36) The dorsal interosseous artery is usually smaller than the volar interosseous. 

 It passes dorsally between the proximal border of the interosseous membrane and the 

 oblique cord, and then between the supinator and abductor pollicis longus (O.T. ext. 

 oss. met. poll.), after which it runs distally, between the superficial and deep muscles on 

 the dorsum of the forearm, to the wrist. At the wrist it anastomoses with the volar inter- 

 osseous artery and with the dorsal carpal arch. As it crosses the abductor pollicis 

 longus it is accompanied by the dorsal interosseous nerve, but in the remainder of its 

 course it is separated from the nerve by the deep muscles. 



Branches. (a) An interosseous recurrent branch is given off at the dorsal margin of the 

 distal border of the supinator. It runs proximally, on the dorsal surface of the supinator, 

 under cover of the anconeus, to the back of the lateral epicondyle of the humerus, where i 

 anastomoses with the posterior terminal branch of the profunda and with branches of the 

 inferior ulnar collateral artery. (6) Muscular branches to both superficial and deep muscles 

 the dorsum of the forearm, (c) Cutaneous branches to the skin on the dorsum of the forearm 

 and the wrist. 



(4) The volar carpal branch of the ulnar artery is a small branch, given off proxima 

 to the transverse carpal ligament; it passes towards the radial side, deep to the flexoi 

 tendons and their sheaths, on the volar surface of the proximal attachments of the vola) 

 radio-carpal ligament, and anastomoses with the volar carpal branch of the radial to forn 

 the volar carpal arch. 



