28 THE SUPERIOR EXTREMITY 



from the nipple, in order to avoid injuring the lactiferous ducts. 

 If the retro-mammary abscess is caused by a forward spread 

 from deeper structures, the breast may be turned upwards 

 by a long curved incision in the infra-mammary groove. In 

 this way good access is obtained and no important structures 

 are injured. The same approach serves for removal of the 

 breast in chronic mastitis and other simple conditions. 



THE AXILLA. The axilla is the space between the upper 

 part of the chest wall and the proximal part of the upper limb. 

 In shape it resembles a pyramid with a blunted apex, through 

 which the great vessels and nerves pass from the root of the 

 neck to the axilla. The apex is bounded, in front, by the 

 middle third of the clavicle, behind, by the upper border of the 

 scapula, and medially, by the outer border of the first rib. 



Axillary Fascia. The hollo wed-out base of the pyramid, 

 i.e. the floor of the axilla, is formed by the axillary fascia, which 

 is an extremely strong sheet. It is continuous in front with 

 the fascial envelope of the pectoralis major, and behind with 

 that of the latissimus dorsi. Below, and medially, it blends 

 with the fascia covering the serratus anterior (magnus), and 

 it is continuous laterally with the deep fascia of the arm. Owing 

 to the great strength of the axillary fascia, abscesses rarely 

 rupture through it spontaneously. 



The Anterior Wall of the Axilla consists of two 

 strata. The Pectoralis major and its fascia form the superficial, 

 and the Pectoralis minor and the clavi-pectoral fascia form 

 the deep layer. 



The Pectoral Fascia closely envelops the pectoralis major. 

 Above, it is attached to the clavicle, and, in its lateral part, 

 it forms the roof of the superficial infra-clavicular triangle. 

 Medially, it is attached to the sternum, and below it is continuous 

 with the fascial covering of the external oblique and the serratus 

 anterior. Laterally, it blends with the axillary fascia below 

 and with the fascia of the arm above. 



The pectoral fascia contains the efferent mammary lymph 

 vessels, and hence the necessity for its exposure and removal in 

 cancer of the breast. The best access to the fascia is obtained 

 by an incision extending from the insertion of the pectoralis 

 major to the tip of the eighth costal cartilage of the opposite 

 side (Stiles). This incision divides so as to enclose the tumour 

 and an equally wide area of skin and cutaneous lymph vessels 

 all round it. 



