AXILLARY ARTERY. 321 



tween those vessels which it serves to connect ; namely, the arteries 

 of the superior and inferior extremities." 



Varieties of the subclavian Arteries. Varieties in these arteries are 

 rare ; that which most frequently occurs is the origin of the right 

 subclavian, from the left extremity of the arch of the aorta, below the 

 left subclavian artery. The vessel, in this case, curves behind the 

 oasophagus and right carotid artery, and sometimes between the oeso- 

 phagus and trachea, to the upper border of the first rib on the right 

 side of the chest, where it assumes its ordinary course. In a case* 

 of subclavian aneurism on the right side, above the clavicle, which 

 happened during the summer of 1839, Mr. Liston proceeded to per- 

 form the operation of tying the carotid and subclavian arteries at their 

 point of division from the innominata. Upon reaching the point where 

 the bifurcation should have existed, he found that there was no sub- 

 clavian artery. With that admirable self-possession which distinguishes 

 this eminent surgeon in all cases of emergency, he continued his dis- 

 section more deeply, towards the vertebral column, and succeeded in 

 securing the artery. It was ascertained after death, that the arteria 

 innominata was extremely short, and that the subclavian was given off 

 within the chest from the posterior aspect of its trunk, and pursued a 

 deep course to the upper margin of the first rib. In a preparation 

 which was shewn to me in Heidelberg some years since by Professor 

 Tiedemann, the right subclavian artery arose from the thoracic aorta, 

 as low down as the fourth dorsal vertebra, and ascended from that 

 point to the border of the first rib. Varieties in the branches of the 

 snbclavian are not unfrequent ; the most interesting is the origin of 

 the left vertebral, from the arch of the aorta, of which I possess several 

 preparations. 



AXILLARY ARTERY. 



The axillary artery forms a gentle curve through the middle of the 

 axillary space from the lower border of the first rib to the lower border 

 of the latissimus dorsi, where it becomes the brachial. 



Relations. After emerging from beneath the margin of the costo- 

 coracoid membrane, it is in relation with the axillary vein, which lies 

 at first to the inner side, and then in front of the artery. Near the 

 middle of the axilla it is embraced by the two heads of the median 

 nerve, and is covered in by the pectoral muscles. Upon the inner or 

 thoracic side it is in relation, first, with the first intercostal muscle ; 

 it next rests upon the first serration of the serratus magnus ; and is 

 then separated from the chest by the brachial plexus of nerves. By 

 its outer or humeral side it is at first separated from the brachial 

 plexus by a triangular cellular interval; it next rests against the 

 tendon of the subscapularis muscle ; and thirdly, upon the coraco- 

 brachialis muscle. 



* This case is recorded in the Lancet, vol. i. 1839-40, pp. 3/ and 41Q. 



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