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THE ARTERIES. 



Outer side. 

 Brachial plexus. 



Inner side. 

 Axillary vein. 



Behind. 



Firat Intercostal space, and Intercostal muscle. 

 Second and third serrations of Serratus magnus. 

 Posterior and Internal anterior thoracic nerves. 



The second portion of the axillary artery lies behind the Pectoralis minor. It 

 is covered in front, by the Pectoralis major and minor muscles ; behind, it is 

 separated from the Subscapularis by a cellular interval ; on the inner side is the 

 axillary vein. The cords of the brachial plexus of nerves surround the artery, and 

 separate it from direct contact with the vein and adjacent muscles. 



RELATIONS OF THE SECOND PORTION OF THE AXILLARY ARTERY. 



In front. 

 Pectoralis major and minor. 



Outer side. 

 Outer cord of plexus. 



Inner side. 

 Axillary vein. 

 Inner cord of plexus. 



Behind. 

 Subscapularis. 

 Posterior cord of plexus. 



The third portion of the axillary artery lies below the Pectoralis minor. It is 

 in relation, in front, with the lower part of the Pectoralis major above, being 

 covered only by the integument and fascia below, where it is crossed by the inner 

 head of the median nerve ; behind, with the lower part of the Subscapularis and 

 the tendons of the Latissimus dorsi and Teres major; on its outer side, with the 

 Coraco-brachialis ; on its inner or thoracic side, with the axillary vein. The nerves 

 of the brachial plexus bear the following relation to the artery in this part of its 

 course : on the outer side is the median nerve, and the musculo-cutaneous for a 

 short distance; on the inner side, the ulnar, the internal, and lesser internal 

 cutaneous nerves ; and behind, the musculo-spiral and circumflex, the latter 

 extending only to the lower border of the Subscapularis muscle. 



Peculiarities. The axillary artery, in about one case out of every ten, gives off a large 

 branch, which forms either one of the arteries of the forearm or a large muscular trunk. In the 

 first set of cases this artery is most frequently the radial (1 in 33), sometimes the ulnar (1 in 72), 

 and, very rarely, the interosseous (1 in 506). In the second set of cases the trunk has been 

 found to give origin to the subscapular, circumflex, and profunda arteries of the arm. Some- 

 times only one of the circumflex, or one of the profunda arteries, arose from the trunk. 

 In these cases the brachial plexus surrounded the trunk of the branches, and not the main 

 vessel. 



RELATIONS OF THE THIRD PORTION OF THE AXILLARY ARTERY. 



In front. 



Integument and fascia. 

 Pectoralis major. 

 Inner head of median nerve. 



Outer side. 

 Coraco-brachialis. 

 Median nerve. 

 Musculo-cutaneous nerve. 



Inner side. 

 Ulnar nerve. 



Internal cutaneous nerves. 

 Axillary veins. 



Behind. 

 Subscapularis. 



Tendons of Latissimus dorsi and Teres major. 

 Musculo-spiral and circumflex nerves. 



