790 
Branches.—(w) Nutrient to the radius and ulna; (b) Muscular to the adjacent muscles ; 
THE VASCULAR SYSTEM. 
(ce) The anterior communicating, a slender branch which descends behind the pronator quadratus 
and in front of the interosseous membrane to anastomose with the anterior carpal arch ; 
(d) Small anastomotic branches are given off at the back of the forearm to anastomose with the 
Triceps 
Anconeus 
Supinator brevis 
Posterior inter- 
osseous recurrent 
artery 
Posterior inter- 
osseous artery 
Flexor carpi 
ulnaris 
Extensor carpi 
ulnaris 
Anterior inter- 
osseous artery 
Posterior inter- 
osseous artery 
Posterior carpal 
arch 
Superior per- 
forating artery 
Dorsal inter- 
osseous arteries 
Snpinator longus 
Extensor carpi 
radialis longior 
Extensor carpi 
ulnaris 
Extensor communis 
digitorum 
Extensor carpi 
radialis brevior 
Posterior 
~ interosseous nerve 
Pronator radii teres 
Extensor ossis 
metacarpi pollicis 
Extensor longus 
pollicis 
Extensor brevis 
pollicis 
Extensor indicis 
Radial artery 
Dorsalis pollicis 
— arteries 
Dorsalis indicis 
Fic. 565.—THE PosTERIOR INTEROSSEOUS ARTERY AND THE 
SECOND PART oF THE RADIAL ARTERY, WITH THEIR. BRANCHES. 
posterior or interosseous artery ; 
(ec) The comes nervi mediani (a. 
mediana) is a long slender branch 
which rises from the upper part of 
the artery and descends in the front 
of the median nerve to the palm, 
where it anastomoses with recurrent 
branches of the superficial palmar 
arch. 
(34) The posterior inter- 
osseous trunk (a. interossea 
dorsalis) is usually smaller than 
the anterior interosseous. It 
passes backwards between the 
upper border of the interosseous 
membrane and the oblique liga- 
ment, and then between the 
supinator brevis and the extensor 
ossis metacarpi pollicis, after 
which it descends between the 
superficial and deep muscles on 
the back of the forearm to the 
wrist, where it anastomoses with 
the anterior interosseous artery 
and with the posterior carpal 
arch. As it crosses the extensor 
ossis metacarpi pollicis it is 
accompanied by the posterior 
interosseous nerve, but in the 
remainder of its course it 1s 
separated from the nerve by the 
deep muscles. 
Branches.— (a) <A posterior 
interosseous recurrent (a. interossea 
recurrens) branch is given off as 
soon as the posterior interosseous 
artery has passed beneath the lower 
border of the supinator brevis. It 
ascends on the posterior surface of 
the supinator brevis, under cover 
of the anconeus, to the back of the 
external condyle of the humerus, 
where it anastomoses with the 
posterior terminal branch of the 
superior profundaand with branches 
of the anastomotic artery. (0) 
Muscular branches to both super- 
ficial and deep muscles on the back 
of the forearm. (c) Cutaneous 
branches to the skin on the back 
of the forearm and the back of the 
wrist. : 
(d) The anterior ulnar carpal 
(ramus carpeus volaris), a small 
branch given off above the 
anterior annular ligament, passes 
outwards beneath the flexor 
tendons and their sheaths on the anterior surface of the carpal ligaments, and anastomoses 
with the anterior carpal branch of the radial to form the anterior carpal arch. 
(ce) The posterior ulnar carpal branch (ramus carpeus dorsalis) arises from the 
back of the inner side of the ulnar artery just above the pisiform bone. It passes 
backwards beneath the flexor and extensor carpi ulnaris muscles to the back of the 
