Volltext: The Cyclopaedia of Anatomy and Physiology, vol 1: A-Dea (1)

THE BRACHIAL OR HUMERAL ARTERY. 
465 
BRACHIAL OR HUMERAL ARTERY 
(arteria brachialis, humeraria. Germ, die Ar- 
marterie.) This artery is the continuation of 
the trunk of the axillary. It commences at the 
inferior margin of the tendons of the teres ma¬ 
jor and latissimus dorsi, whence it extends to 
about an inch below the bend of the elbow, 
where it usually divides into the radial and 
ulnar arteries ; but not unfrequently this divi¬ 
sion takes place high in the arm. 
The brachial artery lies on the internal side 
of the arm above, but in its course downwards 
it gradually advances in an oblique direction 
until it gets completely to the anterior surface 
of the limb, where it is found situated nearly 
midway between the condyles of the humerus 
in front of the elbow joint ; it is superficial in 
the whole line of its course, in every part of 
which its pulsations can easily be felt, and 
sometimes, in the arms of thin persons, are 
I distinctly visible. 
Relations.—Anteriorly the brachial artery 
is overlapped, for about its upper fourth, by the 
coraco-brachialis muscle and the median nerve; 
for the greater part of its course down the arm 
it is covered by the brachial aponeurosis, to 
which is added, where it crosses the elbow, the 
falciform expansion sent off from the tendon of 
the biceps to the internal condyle : the median 
basilic vein also lies in front of it opposite the 
bend of the elbow. Posteriorly, for about a 
L third of its length from its commencement it 
lies in front of the triceps, from which it is se¬ 
parated by a quantity of loose cellular tissue 
which envelopes the musculo-spiral nerve ; in 
its inferior two-thirds it rests on the brachiæus 
anticus. Internally it is covered by the bra¬ 
chial aponeurosis at its superior part, where the 
ulnar nerve is also in contact with it. The me¬ 
dian nerve which crosses it, sometimes super¬ 
ficially, and at other times passing more deeply, 
in the middle of the arm gets to its internal 
side, and continues to hold this relation to it in 
E the remainder of its course. Externally it lies 
at first on the internal side of the humerus, from 
which it is separated as it descends by the thin 
muscular expansion in which the coraco-brachi¬ 
alis terminates at the lower part of its insertion ; 
in the remainder of its course the inner edge of 
the biceps bounds it. The fleshy belly of this 
muscle also partially covers it in front, a little 
below the middle of the arm. At the bend of 
the elbow, the relations of the brachial artery 
become more numerous and complicated; here 
it inclines obliquely outwards and backwards, 
" and sinks into a space which is bounded on the 
inner side by the origins of the pronator and 
flexor muscles of the forearm, and on the out¬ 
side by those of the supinators and extensors, 
the floor of which space is formed by the bra¬ 
chiæus anticus muscle, from which the artery is 
- separated by a layer of adipose cellular mem¬ 
brane. The artery is accompanied in its passage 
into this space by the tendon of the biceps and 
the median nerve, the former being situated to 
its radial side, the latter to its ulnar; and it is 
at the bottom of this space, opposite the coro- 
noid process of the ulna, that the subdivision 
of the artery into radial and ulnar usually takes 
VOL. I. 
place. As it enters the space the artery is 
crossed by the semilunar fascia of the biceps, by 
which it is separated from the internal cutaneous 
nerve and median basilic vein. (For further par¬ 
ticulars on this stage of the artery, see Elbow, 
Region of the.) 
Two venæ comités accompany the brachial 
artery : they are included in its sheath, and lie 
one on either side of it, often communicating 
by several transverse branches which cross the 
artery in front. 
So superficial is the position of this artery 
from its origin till it enters the region of the 
bend of the elbow, that it may be exposed during 
life in any part of its course with facility, and, 
if the operator use only common caution, with 
safety. In all this course the artery may be felt, 
and in the upper third the operator may avail 
himself of the inner side of the coraco-brachialis 
muscle as a guide, and in the middle third, of 
the inner edge of the belly of the biceps. In 
both situations the operator has to avoid in¬ 
juring the cutaneous nerves, and the median 
and ulnar nerves, as well as the basilic vein, 
which sometimes passes up as high as the 
axilla. He should also bear in mind the po¬ 
sition of the inferior profunda artery, which 
is sometimes of a large size; and from its 
direction, as well as its relation to the ulnar 
nerve, presents a considerable resemblance to 
the brachial trunk. 
Branches.—The brachial artery furnishes a 
variable number of branches from its external 
side, none of which is of sufficient importance 
to be distinguished by a name ; they are dis¬ 
tributed to the os humeri, the deltoid, coraco- 
brachialis, biceps, andbrachiæus anticus muscles, 
and to the integuments. From its internal side, 
however, there usually arise, in addition to 
several small twigs sent to the triceps, teres 
major, latissimus dorsi, and the integuments, 
three branches of more considerable size, and 
which derive their principal importance from 
being the leading channels of anastomosis be¬ 
tween the brachial trunk and the arteries of the 
forearm. These are, 1, the superior profunda, 
2, the inferior profunda, 3, the anastomotica 
magna.* 
1. The superior profunda (profunda humeri, 
Haller and Sœmm. collaterale externe, Boyer, 
grand musculaire du bras, Chauss.) arises from 
the posterior side of the brachial artery, close to 
the border of the axilla. It sometimes comes 
from the axillary artery by a trunk common to 
it and the posterior circumflex, and occasionally 
it arises from the subscapular. Immediately 
after its origin the profunda superior gives 
several branches to the coraco-brachialis, triceps, 
latissimus dorsi, teres major, and deltoid mus¬ 
cles. Some of these latter, ascending towards 
the acromion process of the scapula, anastomose 
with the thoracica acromialis, supra-scapular and 
posterior circumflex; while the branches sent 
to the latissimus dorsi and teres major anas¬ 
tomose with the subscapular artery. The supe- 
* Sometimes the subscapnlar, and one or both 
of the circumflex arteries, derive their origin flom 
the brachial. 
2 H
	        
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