BRANCHES OF THE BRACHIAL ARTERY. 



535 



Musculo- 

 spiral nerve. 



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

 by far the more 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 

 1 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 corre- 

 spondence between the arteries of the two arms 

 with respect to their irregular division ; for in 

 61 bodies it occurred on one side only in 43 ; 

 on both sides, in different positions, in 13; on 

 both sides, in the same position, in 5. 



The point of bifurcation takes place at 

 different parts of the arm, being most fre- 

 quent in the 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. 



The ulnar sometimes arises from the 

 brachial high up, and accompanies that ves- 

 sel to the lower part of the arm, and descends 

 toward the inner condyle. In the forearm it 



fenerally lies beneath the deep fascia, super- 

 cial to the flexor muscles ; occasionally be- 

 tween the integument and deep fascia, and 

 very rarely beneath the flexor muscles. 



The interosseous artery sometimes arises 

 from the upper part of the brachial or axil- 

 lary ; as it passes down the arm it lies behind 

 the main trunk, and at the bend of the elbow 

 regains its usual position. 



In some cases of high division of the 

 radial the remaining trunk (ulnar interosseous) 

 occasionally passes, together with the median 

 nerve, along the inner margin of the arm to 

 the inner condyle, and then passing from 

 within outward, beneath or through the Pro- 

 nator radii teres, regains its usual position at 

 the bend of the elbow. 



Occasionally the two arteries representing 

 the brachial are connected at the bend of the 

 elbow by a short transverse branch, and are 

 even sometimes reunited. 



Sometimes, long slender vessels, vasa aber- 

 rantia, connect the brachial or axillary arteries with one of the arteries of the forearm or a 

 branch from them. These vessels usually join the radial. 



Varieties in Muscular Relations. 1 The brachial artery is occasionally concealed in some 

 part of its course by muscular or tendinous slips derived from the Ooraco-brachialis, Biceps, 

 Brachialis anticus, and Pronator radii teres muscles. 



Surface Marking. The direction of the brachial artery is marked by a line drawn along 

 the inner edge of the Biceps from the insertion of the Teres major muscle to the point midway 

 between the condyles of the humerus. 



Surgical Anatomy. Compression of the brachial artery is required in cases of amputation 

 and some other operations in the arm and forearm ; and it will be observed that it may be effected 

 in almost any part of the course of the artery. If pressure is made in the upper part of the 

 limb, it should be directed from within outward ; and if in the lower part, from before backward, 

 as the artery lies on the inner side of the humerus above and in front below. The most favor- 

 able situation is about the middle of the arm, where it lies on the tendon of the Coraco -brachial is 

 on the inner flat side of the humerus. 



1 See Struther's Anatomical and Physiological Observations. 



Inferior 

 profunda. 



Anastomotica 

 magna. 



FIG. 303. The brachial artery. 



