404 ARTERIES. 



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 gave 

 origin to the subscapular, circumflex, and profunda arteries of the arm. Sometimes 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. 



Surgical Anatomy. The student having carefully examined the relations of the axillary 

 artery in its various parts, should now consider in what situation compression of this vessel 

 may be most easily effected, and the best position for the application of a ligature to it when 

 necessary. 



Compression of this vessel is required in the removal of tumors, or in amputation of the 

 upper part of the arm ; and the only situation in which this can be effectually made, is in the 

 lower part of its course ; on compressing it in this situation from within outwards upon the 

 humerus, the circulation may be effectually suspended. 



The application of a ligature to the axillary artery may be required in cases of aneurism of 

 the upper part of the brachial ; and there are only two situations in which it may be secured, 

 viz., in the upper, or in the lower part of its course ; for the axillary artery at its central part is 

 so deeply seated, and, at the same time, so closely surrounded with large nervous trunks, that the 

 application of a ligature to it in this situation would be almost impracticable. 



In the lower part of its course, the operation is more simple, and may be performed in the 

 following manner : The patient being placed on a bed, and the arm separated from the side, with 

 the hand supinated, the head of the humerus is felt for, and an incision made through the integu- 

 ment over it, about two inches in length, a little nearer to the anterior than the posterior fold of 

 the axilla. After carefully dissecting through the areolar tissue and fascia, the median nerve 

 and axillary vein are exposed ; the former having been displaced to the outer, and the latter to 

 the inner side of the arm, the elbow being at the same time bent, so as to relax these structures, 

 and facilitate their separation, the ligature may be passed round the artery from the ulnar to the 

 radial side. This portion of the artery is occasionally crossed by a muscular slip derived from 

 the Latissimus dorsi, which may mislead the surgeon during an operation. It may easily be 

 recognized by the transverse direction of its fibres (see p. 272). 



The upper portion of the axillary artery may be tied, in cases of aneurism encroaching so 

 far upwards that a ligature cannot be applied in the lower part of its course. Notwithstanding 

 that this operation has been performed in some few cases, and with success, its performance is 

 f-ttended with much difficulty and danger. The student will remark, that in this situation it 

 would be necessary to divide a thick muscle, and, after separating the costo-coracoid mem- 

 brane, the artery would be exposed at the bottom of a more or less deep space, with the cepha- 

 lic and axillary veins in such relation with it as must render the application of a ligature to 

 this part of the vessel particularly hazardous. Under such circumstances, it is an easier, and, 

 at the same time, more advisable operation, to tie the subclavian artery in the third part of its 

 course. 



In a case of wound of this vessel the general practice of cutting down upon it, and tying it 

 above and below the wounded point, should be adopted in all cases. 



The branches of the axillary artery are 



From 1st Part. \ Superior thoracic. 



( Acromial thoracic. 

 From 2d Part, -j Tho-racica longa. 



( Thoracica alaris. 



( Subscapular. 

 From 3d Part. -! Anterior circumflex. 



( Posterior circumflex. 



The superior thoracic is a small artery, which arises from the axillary, or by a 

 common trunk with the acromial thoracic. Running forwards and inwards along 

 the upper border of the Pectoralis minor, it passes between it and the Pectoralis 

 major to the side of the chest. It supplies these muscles, and the parietes of the 

 thorax, anastomosing with the internal mammary and intercostal arteries. 



The acromial thoracic is a short trunk, which arises from the fore part of the 

 axillary artery. Projecting forwards to the upper border of the Pectoralis minor, 

 it divides into three sets of branches, thoracic, acromial, and descending. The 

 thoracic branches, two or three in number, are distributed to the Serratus magnus 

 and Pectoral muscles, anastomosing with the intercostal branches of the internal 



