788 
THE VASCULAR SYSTEM. 
Relations of the second part.— As it curves round the outer side and the back of 
the wrist, the radial artery lies upon the external lateral ligament of the intercarpal jomt 
back of the trapezium. It is crossed by the extensor ossis metacarpi 
and upon the 
Biceps ——— 
Radial 
recurrent 
artery 
Orbicular 
ligament 
Supinator 
longus 
Muscular 
branch of 
artery 
Radial artery — 
Pronator teres - 
Flexor longus _ 
pollicis 
Pronator _ 
quadratus 
Flexor carpi 
radialis 
Superficialis 
vole 
Princeps 
pollicis 
. . /, f 
Radialis Ys 
indicis if 
Brachial 
artery 
Anastomotic 
artery 
Pronator 
teres 
Ulnar 
recurrent 
artery 
Flexor 
~profundus 
digitorum 
Ulnar artery 
Anterior 
interosseous 
artery 
Anterior 
communicating 
artery 
Deep branch 
of ulnar artery 
Deep palmar 
arch 
Palmar 
interosseous 
arteries 
}i———. Digital 
artery 
Fic. 564.—DEEp DISSECTION OF THE FRONT OF THE 
FOREARM AND HAND, showing the radial and ulnar 
arteries and their branches and the deep palmar arch 
and its branches. 
pollicis, the extensor brevis pollicis, and 
the extensor longus pollicis ; more super- 
ficially it is covered by fascia, in which 
are some filaments of the radial nerve 
and the commencement of the radial vein, 
and by skin, 
Branches of the second part. 
—(1) Dorsales Pollicis.— Two small 
arteries which run along the borders of 
the dorsal aspect of the thumb; they 
supply the skin, tendons, and joints, and 
anastomose with the palmar digital 
arteries. 
(2) Dorsalis Indicis.—_A_ slender 
artery which runs downwards on the 
war head of the first dorsal interosseous 
muscle and along the dorsal aspect of 
the radial border of the index-finger. 
(3) and (4) The metacarpal or first 
dorsal interosseous and posterior radial 
carpal arise by a common trunk which 
crosses beneath the extensor longus 
pollicis. 
(2) The metacarpal branch (a. metacarpea 
dorsalis) descends on the dorsal aspect of the 
second dorsal interosseous muscle, and divides 
opposite the heads of the metacarpal bones 
into two digital branches which supply the 
adjacent sides of the index and middle 
fingers. (b) The posterior carpal branch 
(ramus carpeus dorsalis) runs inwards on 
the dorsal carpal ligaments, and beneath the 
extensor tendons, to anastomose with the 
posterior carpal branch of the ulnar artery, 
and to complete the dorsal carpal arch which 
receives the terminations of the anterior and 
posterior interosseous arteries. The dorsal 
carpal arch gives off the second and third 
dorsal interosseous arteries (aa. metacarpe 
dorsales), which descend on the dorsal aspects 
of the third and fourth dorsal interosseous 
muscles as far as the heads of the metacarpal 
bones, where each divides into two branches 
(aa. digitales dorsales), for the adjacent sides 
of the third and fourth and the fourth and 
fifth fingers respectively. 
Each dorsal interosseous artery is con- 
nected with the deep palmar arch by a 
superior perforating branch which passes 
through the upper part of the corresponding 
interosseous space, and with a digital branch 
from the superficial palmar arch by an 
inferior perforating branch which passes 
through the lower part of the space. 
Relations of the third part.— 
The third part of the radial artery passes 
forwards between the two heads of the 
first dorsal interosseous muscle to reach 
the palm, where it turns inwards beneath 
the upper part of the oblique adductor muscle of the thumb, and, after passing through 
the upper fibres of the transverse adductor, or between the adjacent borders of the oblique 
and transverse adductors, unites with the deep branch of the ulnar artery, completing the 
deep palmar arch. 
Mee ee ON Ba a se te lt ES oe ee F en~graieter =, 
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