THE BREAST AND AXILLA 33 



the lateral and posterior cords of the brachial plexus ; to the 

 medial side, and overlapping the artery anteriorly, is the axillary 

 vein. 



Ligature of this part of the artery has been referred to 

 already (p. 30). The collateral circulation is carried on by the 

 scapular anastomosis, where the transverse scapular (supra- 

 scapular) (p. 14) and the descending branch of the transverse 

 cervical, from the subclavian (p. 12), meet the subscapular and 

 circumflex scapular (dorsalis scapulae) branches from the 

 axillary. Further, branches from the intercostals anastomose 

 on the chest wall with the lateral (long) thoracic and subscapular 

 arteries and with the pectoral branches of the thoraco-acromial. 



The superior thoracic is the only branch of the first part of 

 the axillary artery. It crosses the apex of the axilla to supply 

 the lymph glands and other structures in the first intercostal 

 space. 



The Second Part of the axillary artery has the lateral 

 cord of the brachial plexus to its lateral side, the posterior 

 cord behind it, and the medial cord and the medial anterior 

 thoracic nerve, which separate the artery from the axillary vein, 

 to its medial side. Behind the artery and the posterior cord 

 there is a pad of fat, which intervenes between them and the 

 subscapularis muscle. 



The branches of this part of the artery are the thoraco- 

 acromial (p. 30) and the lateral thoracic (p. 31). 



The Third Part of the axillary artery lies under cover 

 of the pectoralis major above, but it is subcutaneous below. 

 There are two nerves on each side of the artery. Laterally, lie 

 the lateral head of the median and the musculo-cutaneous nerve, 

 which deviates laterally to pierce the coraco-brachialis (Fig. 10). 

 Anteriorly, lie the medial head of the median and the medial 

 cutaneous nerve of the forearm (internal cutaneous nerve). 

 Medially, the ulnar nerve separates the artery from the axillary 

 vein, and the medial cutaneous nerve of the arm (lesser internal 

 cutaneous nerve) is closely applied to the medial side of the 

 vein. Posteriorly are the radial (musculo-spiral) and axillary 

 (circumflex) nerves, but the latter leaves the artery at the 

 lower border of the subscapularis by passing backwards into 

 the quadrilateral space. 



The Third Part of the axillary artery is superficial, and is 

 the site of election for Ligation. The vessel may be tied 

 immediately above the origin of the subscapular or between 



3 



