2 6o APPLIED ANATOMY. 



Second Portion. The second portion of the axillary lies beneath the pecto- 

 ralis minor muscle. It is 3 cm. ( i ^ in. ) long and while never ligated at this point it is 

 nevertheless frequently exposed while clearing out the axilla for malignant growths of 

 the breast. Owing to its being covered by the pectoralis minor and major muscles 

 the artery cannot be compressed at this point in its course. 



Branches. Its ' ^nches are the alar thoracic and long thoracic. The alar tho- 

 racic are small brahc.ies of little importance supplying the fat and glands of the 

 axilla. 



The long thoracic or external mammary is of considerable importance on account 

 of its size and because it is encountered in operations on the breast and axilla. It 

 passes down along the lower (outer) border of the pectoralis minor, giving branches 

 to it and the pectoralis major; some branches go to the axilla and serratus anterior, 

 and others, which may be of considerable size in the female, wind around the lower 

 portion of the pectoralis major or pierce it to supply the mammary gland. Posterior 



Pectoralis major 

 Superior thoracic artery. 



Acromiothoracic art 



Coracoid process 



Pecloralis minor muscle 



Axillary artery 



Axillary vein 



Alar thoracic artery 



Lontf head of biceps 



Coracohrachialis and short. 



head of biceps 



Musculocutaneous nerve 



Long thoracic artery J 

 Anterior circumflex artery 

 Subscapular artery 

 Posterior circumflex artery 

 Pectoralis major muscle 

 Median nerve 



Internal cutaneous nerve. 

 Ulnar 



Lesser internal^ 



cutaneous nerve' 'Vl-flfiff' \. \. I-atissimus dorsi 



X^ 'Teres major muscle 

 Intercostohumeral nerve 



FIG. 272. Dissection of the axilla. 



to it is the long or posterior thoracic nerve, or external respiratory nerve of Bell, 

 going to supply the serratus anterior muscle (Fig. 272). 



Relations. Anteriorly is the pectoralis minor muscle, superficial to which is the 

 pectoralis major and skin. Posteriorly lie the posterior cord of the brachial plexus, 

 the fat of the axilla, and the subscapularis muscle; internally is the axillary vein, with 

 the inner cord of the brachial plexus separating the two. Externally is the outer 

 cord of the plexus and farther out is the coracoid process. 



Third Portion. This is about 7.5 cm. (3 in.) long and runs from the lower 

 border of the pectoralis minor to the lower border of the teres major. Its upper 

 portion is under the pectoralis major but its lower portion is subcutaneous because 

 the teres major, forming the edge of the posterior fold of the axilla, extends lower 

 than the anterior fold. It is here that the axillary artery is most easily reached and 

 most often ligated. 



Branches. It gives off three branches, the subscapular, the anterior circumflex, 

 and the posterior circumflex. 



The subscapular artery is of considerable practical importance; it is the largest 

 branch of the axillary and is given off opposite the lower border of the subscapularis 

 muscle. It follows the- lower edge of this muscle down the axillary or outer border 



