598 ANGIOLOGY 



on or through the fibers of the Supinator, but beneath the Anconseus, and anasto- 

 moses with the radial collateral branch of the profunda brachii, the posterior 

 ulnar recurrent and the inferior ulnar collateral. 



The muscular branches (rami musculares) are distributed to the muscles along 

 the ulnar side of the forearm. 



The volar carpal branch (mums carpeus volares; anterior ulnar carpal artery) is a 

 small vessel which crosses the front of the carpus beneath the tendons of the Flexor 

 digitorum profundus, and anastomoses with the corresponding branch of the radial 

 artery. 



The dorsal carpal branch (ramus carpeus dorsalis; posterior ulnar carpal artery) 

 arises immediately above the pisiform bone, and winds backward beneath the 

 tendon of the Flexor carpi ulnaris ; it passes across the dorsal surface of the carpus 

 beneath the Extensor tendons, to anastomose with a corresponding branch of the 

 radial artery. Immediately after its origin, it gives off a small branch, which runs 

 along the ulnar side of the fifth metacarpal bone, and supplies the ulnar side of the 

 dorsal surface of the little finger. 



The deep volar branch (ramus volaris profundus; profunda branch} (Fig. 528) 

 passes betw r een the Abductor digiti quinti and Flexor digiti quinti brevis and 

 through the origin of the Opponens digiti quinti; it anastomoses with the radial 

 artery, and completes the deep volar arch. 



The superficial volar arch (arcus volaris superficialis ; superficial palmar arch) 

 (Fig. 527) is formed by the ulnar artery, and is usually completed by a branch 

 from the a. volaris indicis radialis, but sometimes by the superficial volar or by 

 a branch from the a. princeps pollicis of the radial artery. The arch passes across 

 the palm, describing a curve, with its convexity downward. 



Relations. The superficial volar arch is covered by the skin, the Palmaris brevis, and the 

 palmar aponeurosis. It lies upon the transverse carpal ligament, the Flexor digiti quinti brevis 

 and Opponens digiti quinti, the tendons of the Flexor digitorum sublimis, the Lumbricales, and 

 the divisions of the median and ulnar nerves. 



Three Common Volar Digital Arteries (aa. digitales volares communes; palmar digital 

 arteries) (Fig. 527) arise from the convexity of the arch and proceed downward 

 on the second, third, and fourth Lumbricales. Each receives the corresponding 

 volar metacarpal artery and then divides into a pair of proper volar digital arteries 

 (aa. digitales volares propriw; collateral digital arteries) which run along the con- 

 tiguous sides of the index, middle, ring, and little fingers, behind the corresponding 

 digital nerves ; they anastomose freely in the subcutaneous tissue of the finger tips 

 and by smaller branches near the interphalangeal joints. Each gives off a couple 

 of dorsal branches which anastomose with the dorsal digital arteries, and supply 

 the soft parts on the back of the second and third phalanges, including the matrix 

 of the finger-nail. The proper volar digital artery for medial side of the little 

 finger springs from the ulnar artery under cover of the Palmaris brevis. 



THE ARTERIES OF THE TRUNK. 



THE DESCENDING AORTA. 



The descending aorta is divided into two portions, the thoracic and abdominal, 

 in correspondence with the two great cavities of the trunk in which it is situated 



The Thoracic Aorta (Aorta Thoracalis) (Fig. 530). 



The thoracic aorta is contained in the posterior mediastinal cavity. It begins 

 at the lower border of the fourth thoracic vertebra where it is continuous with 

 the aortic arch, and ends in front of the lower border of the twelfth at the aortic 





