THE AXILLARY ARTERY. 591 



Surface Marking. The course of the axillary artery may be marked out by raising the 

 arm to a right angle and drawing a line from the middle of the clavicle to the point where the 

 tendon of the Pectoralis major crosses the prominence caused by the Coraco-brachialis as it 

 emerges from under cover of the anterior fold of the axilla. The third portion of the artery can 

 be felt pulsating beneath the skin and fascia, at the junction of the anterior with the middle 

 third of the space between the anterior and posterior folds of the axilla, close to the inner border 

 of the Coraoo-brachi&li& 



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 the vessel may be 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 ; by pressing on it in this situation from within outward against the 

 huinerus the circulation may be effectually arrested. 



The axillary artery is perhaps more frequently lacerated than any other artery in the body, 

 with the exception of the popliteal, by violent movements of the upper extremity, especially in 

 those cases where its coats are diseased. It has occasionally been ruptured in attempts to reduce 

 old dislocations of the shoulder-joint. This lesion is most likely to occur during the preliminary 

 breaking down of adhesions, in consequence of the artery having contracted adhesions to the 

 capsule of the joint. Aneurism of the axillary artery is of frequent occurrence, a large percentage 

 of the cases being traumatic in their origin, due to the violence to which it is exposed in the 

 varied, extensive, and often violent movement of the limb. 



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

 aneurism of the upper part of the brachial or as a distal operation for aneurism of the sub- 

 clavian : and there are only two situations in which it can be secured viz. in the first and in the 

 third parts 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 that situation would be almost impracticable. 



In the third part of its course the operation is most 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. an incision is made through the integument forming the floor of the axilla 

 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 the 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. The occasional existence of this 

 muscular fasciculus was spoken of in the description of the muscles. It may easily be recognized 

 by the transverse direction of its fibres. 



The first portion of the axillary artery may be tied in cases of aneurism encroaching so far 

 upward 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 

 attended 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 membrane, 

 the artery would be exposed at the bottom of a more or less deep space, with the cephalic 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. 



The vessel can be best secured by a curved incision with the convexity downward from a 

 point half an inch external to the Sterno-clavicular joint to a point half an inch internal to the 

 coracoid process. The linib is to be well abducted and the head inclined to the opposite side, 

 and this incision carried through the superficial structures, care being taken of the cephalic vein 

 at the outer angle of the incision. The clavicular origin of the Pectoralis major is then divided 

 in the whole extent of the wound. The arm is now to be brought to the side, and the upper 

 edge of the Pectoralis minor defined and drawn downward. The costo-coracoid membrane is to 

 be carefully torn through with a director close to the coracoid process, and the axillary sheath 

 exposed : this is to be opened with especial care on account of the vein overlapping the artery. 

 The needle should be passed from below, so as to avoid wounding the vein. 



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

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



Collateral Circulation after Ligature of the Axillary Artery. If the artery be tied 

 above the origin of the acrornial thoracic, the collateral circulation will be carried on by the same 

 branches as after the ligature of the subclavian : if at a lower point, between the acromial 

 thoracic and subscapular arteries, the latter vessel, by its free anastomoses with the other 

 scapular arteries, branches of the subclavian. will become the chief agent in carrying on the cir- 

 culation, to which the long thoracic, if it be below the ligature, will materially contribute by its 

 anastomoses with the intercostal and internal mammary arteries. If the point included in the 

 ligature be below the origin of the subscapular artery, it will most probably also be below the 

 origins of the two circumflex arteries. The chief agents in restoring the circulation will then be 



