184 



APPLIED ANATOMY. 



artery from the second to the sixth rib; the second, third, and fourth are the largest 

 and may bleed freely in detaching the pectoralis major. To the outer side and 

 below is the long thoracic artery, also called the external mammary; it descends 

 along the outer edge of the pectoralis minor, sending branches inward around the 

 edge of the pectoralis major to the mammary gland. The intercostal arteries also 

 contribute somewhat to the blood supply of the gland. 



Lymphatics. The breast is exceedingly well supplied with lymphatics. 

 They are composed of a deep set around the lobules and ducts, and a siiperficial set 

 which together with the deep lymphatics forms a plexus around the nipple called the 

 subareolar plexus. They drain mainly toward the axilla into the lymph-nodes along 

 the edge of the pectoralis major but also communicate with the nodes around the 

 subclavian artery and those in the anterior mediastinum which accompany the inter- 

 nal mammary artery. 



The axillary nodes are in three sets: one along the edge of the pectoralis 

 major muscle (pectoral nodes}, another further back along the anterior edge of the 

 scapula {scapular nodes), and a third following the course of the axillary artery 



Delto-pectoral node 



Brachial node 



- Subclavian node 



Subscapular node 



Anterior pectoral node 



Vessel passing to anterior 



pectoral node 



Inferior pectoral node 



Vessel passing to 

 subclavian node 



Intermediate node 



Subareolar plexus 

 over mammary 

 gland 



FIG. 207. Lymphatics of the breast. (Pbirier and Cunp.) 



(humeral nodes). In addition to these there are some infradavicular or subclavian 

 nodes between the deltoid and pectoralis major and at the inner edge of the pectoralis 

 minor muscles; these are comparatively rarely involved primarily. The axillary 

 nodes are continuous and communicate with the subclavian and supraclavicular nodes, 

 and these latter are frequently enlarged subsequent to the axillary infection. The 

 anastomosis of the lymphatics across the median line has been thought to account 

 for the occurrence of the disease in the opposite breast or axilla. As shown by 

 Sappey, some if not all of the lymphatics of even the sternal portion of the breast 

 drain into the axilla and not into the anterior mediastinum, thus accounting for the 

 axillary involvement when the inner portion of the breast is affected. These five 

 sets of nodes communicate with each other, and any one may be alone involved. 

 The supraclavicular set do not become involved primarily because no vessels run 

 directly from the breast to them; they are affected secondarily to involvement of the 

 axillary or subclavian sets. 



The deep lymphatics of the breast, according to Sappey, follow the ducts to the 

 areola, there anastomosing with the superficial lymphatics to form what he called the 

 subareolar plexus, which drains by two trunks into the axilla. The lymphatics of the 



