640 THE VASCULAR SYSTEMS 



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 lo\ver 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 incising the costocoracoid 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 in the first part of its course can best be secured through a curved incision the 

 convexity of which is downward. This incision passes from a point half an inch external to 

 the sternoclavicular joint to a point half an inch internal to the coracoid process. The limb 

 is to be well abducted and the head inclined to the opposite side, and this incision is carried 

 through the superficial structures, care being taken to avoid the cephalic vein at the outer 

 angle of the incision. The clavicular origin of the Pectoralis major is then divided in the w^hole 

 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 costocoracoid membrane is to be care- 

 fully divided 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. 



Branches. The branches of the axillary artery are: 



r, . f Superior thoracic. v . f Long thoracic. 



r rom first part < . J . , . b rom second part \ A , 



( Acromiothoracic. ( Alar thoracic. 



( Subscapular. 



From third part < Posterior circumflex. 

 ( Anterior circumflex. 



The superior thoracic (a. thoracalis supremo) is a small artery which arises 

 from the axillary separately or by a common trunk with the acromiothoracic. 

 Running forward and inward along the upper border of the Pectoralis minor, it 

 passes between it and the Pectoralis major to the side of the thorax. It supplies 

 these muscles and the parietes of the thorax, anastomosing with the internal mam- 

 mary and intercostal arteries. 



The acromiothoracic (a. thoracoacromialis) is a short trunk which arises 

 from the fore part of the axillary artery, its origin being generally overlapped 

 by the upper edge of the Pectoralis minor. Projecting forward to the upper 

 border of the Pectoralis minor, it divides into four sets of branches thoracic, 

 acromial, descending, and clavicular. 



The thoracic branches (rami pectorales), two or three in number, are distributed 

 to the Serratus magnus and Pectoral muscles, anastomosing with the intercostal 

 branches of the internal mammary. 



The acromial branch (ramus acromialis) is directed outward toward the acro- 

 mion, supplying the Deltoid muscle, and anastomosing, on the surface of the 

 acromion, with the suprascapular and posterior circumflex arteries. 



The descending or humeral branch (ramus deltoideus) runs in the space between 

 the Pectoralis major and Deltoid, in the same groove as the cephalic vein, and 

 supplies both muscles. 



The clavicular branch (ramus clavicularis), which is very small, runs upward 

 to the Subclavius muscle. 



The long thoracic or the external mammary (a. thoracalis lateralis') passes 

 downward and inward along the lower border of the Pectoralis minor to the side 

 of the thorax, supplying the Serratus magnus, the Pectoral muscles, and mammary 

 gland, and sending branches across the axilla to the axillary nodes and Sub- 

 scapularis; it anastomoses with the internal mammary and intercostal arteries. 



