484 ARTERIES. 



PLAN OF THE KELATIONS OF THE BEACHIAL AKTERT. 



In front. 



Integument and fasciae. 

 Bicipital fascia, median basilic vein. 

 Median nerve. 



Outer side. f \ Inner side. 



Median nerve. / Brachial \ Internal cutaneous and ulnar nerve. 



Coraco-brachialis. \ Artery, j Median nerve. 

 Biceps. 



Behind. 

 Triceps. 



"Musculo-spiral nerve. 

 Superior profunda artery. 

 Coraco-brachialis. 

 Brachialis Anticus. 



BEND OF THE ELBOW. 



At the bend of the elbow, the brachial artery sinks deeply into a triangular 

 interval, the base of which is directed upwards towards the humerus, and the 

 sides of which are bounded, externally, by the Supinator Longus, internally, 

 by the Pronator Eadii Teres ; its floor is formed by the Brachialis Anticus, and 

 Supinator Brevis. This space contains the brachial artery, with its accom- 

 panying veins ; the radial and ulnar arteries; the median and musculo-spiral 

 nerves; and the tendon of the Biceps. The brachial artery occupies the middle 

 line of this space, and divides opposite the coronoid process of the ulna into 

 the radial and ulnar arteries; it is covered, in front, by the integument, the 

 superficial fascia, and the median basilic vein, the vein being separated from 

 direct contact with the artery by the bicipital fascia. Behind, it lies on the 

 Brachialis Anticus, which separates it from the elbow-joint. The median nerve 

 lies on the inner side of the artery, but separated from it below by an interval 

 of half an inch. The tendon of the Biceps lies to the outer side of the space, 

 and the musculo-spiral nerve still more externally, lying upon the Supinator 

 Brevis, and partly concealed by the Supinator Longus. 



Peculiarities of the Artery as regards its Course. The brachial artery, accompanied by the 

 median nerve, may leave the inner border of the Biceps, and descend towards the inner condyle 

 of the humerus, where it usually curves round a prominence of bone, to which it is connected by 

 a fibrous band ; it then inclines outwards, beneath or through the substance of the Pronator Teres 

 muscle, to the bend of the elbow. This variation bears considerable analogy with the normal 

 condition of the artery in some of the carnivora : it has been referred to, above, in the description 

 of the humerus. 



As regards its Division. Occasionally the artery is divided for a short distance at its upper 

 part into two trunks, which are united above and below. A similar peculiarity occurs in the 

 main vessel of the lower limb. 



The point of bifurcation may be above or below the usual point, the former condition being by 

 far the most frequent. Out of 481 examinations recorded by Mr. Quain, some made on the 

 right, and some on the left side of the body, in 386 the artery bifurcated in its normal position. 

 In one case only was the place of division lower than usual, being two or three inches below the 

 elbow-joint. "In 94 cases out of 481, or about one in 5, there were two arteries instead of one 

 in some part, or in the whole of the arm. 



There appears, however, to be no correspondence between the arteries of the two arms, with 

 respect to their irregular division; for in sixty-one bodies it occurred on one side only in forty- 

 three ; on both sides, in different positions, in thirteen ; on both sides, in the same position, in five. 



The point of bifurcation takes place at different parts of the arm, being most frequent in tho 

 upper part, less so in the lower part, and least so in the middle, the most usual point for the 

 application of a ligature ; under any of these circumstances, two large arteries would be found 

 in the arm instead of one. The most frequent (in three out of four) of these peculiarities is the 

 high division of the radial. That artery often arises from the inner side of the brachial, and runs 

 parallel with the main trunk to the elbow, where it crosses it, lying beneath the fascia ; or it may 

 perforate the fascia, and pass over the artery immediately beneath the integument. 



