AXILLARY ARTERY: BRANCHES. 771 



the vein internally. The internal anterior thoracic nerve is sometimes seen coming 

 out between the vein and the artery. The arm should be brought to the side to 

 relieve tension on the vessels, especially the vein, which in that position will be least 

 prominent. The needle should be passed from within and below outward and upward. 



2. With the arm abducted, so as to make evident the fissure between the sternal 

 and clavicular portions of the pectoralis major, an oblique incision is made over this 

 space and will usually begin about a half-inch from the sterno-clavicular joint. The 

 muscular interspace having been exposed, its sides are separated, not directly back- 

 ward, but backward and upward towards the clavicle. The arm is brought to the 

 side to relax the pectoral fibres. The pectoralis minor and the space between it and 

 the clavicle are reached, and if the latter is too contracted, the muscle may be divided 

 close to the coracoid process. The artery is then exposed and secured as in the 

 method above given. 



The second portion is not formally ligated, but may have a ligature applied when- 

 ever, as in the last-mentioned method, the lesser pectoral has been divided. 



Ligation of the third portion of the subclavian artery is, on account of its ease 

 of performance, almost invariably preferred to any of these operations. 



The third portion of the axillary is that almost always selected for ligation ♦)f 

 that vessel, for a similar reason. 



The line of the vessel, the arm being at right angles to the trunk, is from the 

 junction of the anterior and middle thirds of the summit of the axilla to the middle of 

 the bend of the arm at the elbow. This line will be found to follow the inner margin 

 of the coraco-brachialis muscle, the prominence of which may be seen just internal to 

 the swell of the biceps where it emerges from beneath the anterior axillary fold. An 

 incision is made on this line through the skin and superficial and deep fasciae, and the 

 fibres of the coraco-brachialis margin are exposed and cleared. Internally to them 

 lies the vessel, the median and musculo-cutaneous nerves external to it, and the inter- 

 nal cutaneous nerve and axillary vein on its inner side. 



The needle should be passed from within outward. 



The collateral circulation is established after ligation of the first portion above 

 the origin of the acromial thoracic precisely as after ligation of the third portion of 

 the subclavian (page 757). After ligation of the third portion above the origin of 

 the subscapular the anastomoses take place between («) the intercostals, long thoracic, 

 posterior scapular, and suprascapular, and {b) the acromial thoracic, on the cardiac 

 side of the ligature '; and («) the subscapular, and (^b) the posterior circumflex on 

 the distal side. 



When the vessel has been tied between the origins of the subscapular and the 

 two circumflex arteries — probably the point of election (Taylor) — the anastomoses 

 occur between the branches of the axillary and those of the thyroid axis, — i.e., the 

 suprascapular and acromial thoracic above and the posterior circumflex below. Still 

 lower, — i.e., below the circumflex arteries — the collateral circulation is established 

 just as after ligation of the brachial above the superior profunda {g.v.). 



1. The Superior Thoracic Artery. — The superior or short thoracic (a. 

 thoracalis suprema) (Fig. 704) arises just after the axillary has emerged from beneath 

 the subclavius muscle, -and is directed downward and forward to the first intercostal 

 space, the muscles of which it supplies. Not infrequently it gives off a branch which 

 supplies the muscles of the second intercostal space also. Its branches anastomose 

 with those of the internal mammary and acromial thoracic, and occasionally its place 

 is taken by a branch from the latter vessel. 



2. The Acromial Thoracic Artery. — The acromial thoracic (a. thoraco- 

 acromialis) (Fig. 705) is a very constant branch which arises from the front of the 

 axillary artery, a short distance below the superior thoracic. It is directed forward 

 for a short distance, but soon divides into thoracic, clavicular, and acromio-humeral 

 branches. 



Branches. — {a) The thoracic branches (rami pectorales) pass downward and forward to the 

 side of the thorax, supplying the muscles of the second and third, and sometimes of the fourth 

 and fifth intercostal spaces, and also giving branches to the pectoralis major and the pectoralis 

 minor. It anastomoses witH the intercostal arteries and the superior and long thoracics. 



