THE THORACIC AORTA 267 



profimdus digitorum; ulnar side, flexor carpi ulnaris, median 

 nerve above and ulnar nerve below; radial side, flexor sublimis. 



At the wrist the nerve is internal to the artery, and the pisiform 

 bone is internal to the ulnar nerve. 



In the hand, as the superficial arch, it is covered by the skin, 

 palmaris brevis, and palmar fascia. It rests on the annular 

 ligament, superficial tendons, and divisions of the median and 

 ulnar nerves. 



The branches of the ulnar artery are divided into three groups : 



I. Forearm: (a) The anterior ulnar recurrent, to front of the 

 inner condyle, joins the anastomotica magna and inferior 

 profunda. 



(6) The posterior ulnar recurrent, beneath the flexor sublimis 

 to the back of the inner condyle, and between the heads of the 

 flexor carpi ulnaris along the ulnar nerve; joins the posterior 

 interosseous recurrent and inferior profunda arteries. 



(c) The interosseous, to the upper border of the interosseous 

 membrane, where it divides into the anterior and posterior 

 interosseous arteries. The anterior runs on the front of the 

 membrane, which it pierces above the pronator quadratus, to 

 join the posterior branch and the posterior carpal arch. It 

 supplies the median artery to the nerve, muscular branches, and 

 the nutrient vessels of the radius and ulna. A branch joins the 

 anterior carpal arch. The posterior interosseous descends along 

 the back of the forearm, between the superficial and deep 

 muscles, and joins the anterior. It gives off the interosseous 

 recurrent, which ascends beneath the anconeus to join, behind 

 the olecranon, in the anastomosis at the elbow-joint. 



(d) The muscular, to the ulnar side of the forearm. 



II. Wrist: The anterior and posterior carpal join similar 

 branches of the radial to form the carpal arches, the posterior 

 giving a metacarpal branch to the little finger, ulnar side. 



III. Hand: (a) The deep branch joins the radial to form the 

 palmar arch. 



(b) The digital branches from the superficial palmar arch are 

 four, going to the little, ring, middle, and ulnar side of the index 

 finger. 



The Thoracic Aorta 



The thoracic aorta descends from the lower border of the fifth 

 to the front of the last dorsal vertebra. 



