398 



RADIAL ARTERY. 



Several unnamed muscular branches are given by the radial artery to the 

 muscles on the fore part of the arm. 



B. The branches which arise from the radial artery behind the wrist are, 

 the posterior carpal, the metacarpal, the dorsal arteries of the thumb, and 

 the dorsal artery of the index finger. 



(a) The posterior radial carpal is a small but constant branch. It arises 

 beneath the extensor tendons of the thumb, and running inwards on the 

 back of the carpus anastomoses with the posterior uluar carpal branch, 

 completing the arch from which spring the dorsal interosseous arteries of the 

 third and fourth spaces (p. 391). It anastomoses, also, with the terminal 

 branch of the anterior interosseous of the forearm. 



(b) The first dorsal interosseous or metacarpal branch arises beneath the 

 extensor tendons of the thumb, frequently in common with the posterior 

 carpal branch, passes to the interval between the second and third 

 metacarpal bones, communicates with the corresponding perforating branch 

 of the deep palmar arch, and, descending on the second dorsal interosseous 

 muscle, anastomoses with the palmar digital branch at its division between 

 the fingers. 



Fig. 279. 



Fig. 279. DEEP VIEW OF THE ARTERIES OF THE 

 WRIST AND HAND, FROM BEFORE (from R. 

 Quain). 



The anterior annular ligament of the carpus 1ms 

 been divided and the lower part of the common 

 flexors and flexor of the thumb has been re- 

 moved ; portions of these tendons are represented 

 as turned down upon the fingers with parts of the 

 lumbricales muscles; the superficial palmar artery 

 removed, and the interossei muscles are exposed. 

 a, ulnar nerve ; b, tendon of the flexor carpi 

 ulnaris muscle; c, tendon of the flexor carpi 

 radialis ; d, inserted tendon of the extensor ossis 

 metacarpi pollicis ; 1, radial artery ; 1', its lower 

 part before passing back within the extensor ten- 

 dons of the thumb, giving the anterior carpal and 

 superficial volar branches; 2, ulnar artery; 3, 

 anterior interosseous artery before passing behind 

 the pronator quadratus muscle ; 4, radial artery, 

 appearing deeply in the palm between the first and 

 second metacarpal bones and passing into the deep 

 palmar arch ; 5, deep branch of the ulnar artery 

 dipping between the abductor and flexor brevis 

 minimi digiti to join the deep arch and accom- 

 panied by the deep branch of the ulnar nerve ; 6, 

 a palmar digital artery, rising from the first part of 

 the superficial palmar arch ; 7, the princeps pol- 

 licis, and 8, the radialis indicia arteries rising from 

 the radial artery ; 9, 9, 9, interosseous branches 

 of the deep palmar arch proceeding down on the 

 interosseous muscles to join the palmar digital 

 arteries from the superficial arch. 



(c) The dorsal arteries of the thumb, two 



small branches, arising separately or together opposite the head of the meta- 

 carpal bone, run upon the dorsal aspect of the bones of the thumb, one at 

 the radial, the other at the ulnar border. 



(d) The dorsal artery of the index finger, a very small branch, arises 



