BRACHIAL ARTERY BRANCHES. 291 



Varieties of the Axillary Artery. The most frequent peculiarity 

 of this kind is the division of the vessel into two trunks of equal 

 size : a muscular trunk, which gives off some of the ordinary axil- 

 lary branches and supplies the upper arm, and a continued trunk, 

 which represents the brachial artery. The next most frequent variety 

 is the high division of the ulnar which passes down the arm by the 

 side of the brachial artery, and superficially to the muscles proceed- 

 ing from the inner condyle, to its ordinary distribution in the hand. 

 In this course it lies immediately beneath the deep fascia of the fore- 

 arm, and may be seen and felt pulsating beneath the integument. 

 The high division of the radial from the axillary is rare. In one 

 instance, I saw the axillary artery divide into three branches of 

 nearly equal size, which passed together down the arm, and at the bend 

 of the elbow resolved themselves into radial, ulnar, and interosseous. 

 But the most interesting variety, both in a physiological and surgical 

 sense, is that described by Dr. Quain, in his " Elements of Anatomy." 

 " I found in the dissecting-room, a few years ago, a variety not 

 hitherto noticed : it was at first taken for the ordinary high division 

 of the ulnar artery. The two vessels descended from the point of 

 division at the border of the axilla, and lay parallel with one another 

 in their course through the arm ; but instead of diverging, as is 

 usual, -at the bend of the elbow, they converged, and united so as to 

 form a short trunk which soon divided again into the radial and 

 ulnar arteries in the regular way." In a subject, dissected during 

 the past winter in Sydenham College, this variety existed in both 

 arms ; and I have seen several other instances of a similar kind. 



BRACHIAL ARTERY. 



The Brachial artery passes down the inner side of the arm, from 

 the lower border of the latissimus dorsi to the bend of the elbow, 

 where it divides into the radial and ulnar arteries. 



Relations. In its course downwards, it rests upon the coraco- 

 brachialis muscle, internal head of the triceps, brachialis anticus, 

 and the tendon of the biceps. To its inner side is the ulnar nerve ; 

 to the outer side, the coraco-brachialis and biceps muscles ; in front 

 it has the basilic vein, and is crossed by the median nerve. Its 

 relations, within its sheath, are the vense comites. 



Plan of the relations of the Brachial Artery. 



Basilic vein, 

 Deep fascia, 

 Median nerve. 



Inner Side. Outer Side. 

 Ulnar nerve. Brachial Artery. Coraco-brachialis, 

 Biceps. 



Behind. 



Short head of triceps, 

 Coraco-brachialis, 

 Brachialis anticus, 

 Tendon of biceps. 



