The Axilla. 39 



brachial plexus of nerves, external respiratory nerve and 

 the adipose tissue supporting these structures. The 

 glands of the axilla, ten or twelve in number, are arranged 

 in three sets, anterior, middle and posterior. The anter- 

 ior set is situated on the serratus magnus close to the 

 lower border of the pectoralis minor, i. e. y in the region of 

 the long thoracic artery and receives the lymphatics from 

 the anterior sur-face of the trunk as low down as the um- 

 bilicus. Any source of irritation such as mammary 

 cancer, septic wounds, etc., in this territory will first 

 affect this set. The posterior group is placed near the 

 lower border of the latiss. dorsi along the course of the 

 subscapular artery and receives the lymphatics from the 

 back as low down as the iliac crest, The middle set are 

 found along the axillary vein and therefore at the outer 

 part of the axilla. These latter glands receive not only 

 the lymphatics from the upper limb but those from the 

 anterior and posterior groups as well, so that when, for 

 instance, the anterior set is affected in mammary cancer, 

 as the disease progresses the middle set becomes involved 

 and through this the disease spreads to the cervical glands 

 involving first, however, two or three subclavian glands 

 in the deep subclavian triangle. 



Blood Vessels. Along the outer wall of the axillary 

 space lie the main blood vessels for the upper limb, viz., 

 the axillary artery and vein. The artery ends at the 

 lower border of the teres major and is therefore longer 

 than the vein, which depends for its length on the point 

 of union of its constituents, i.e., the basilic vein and the 

 venae comites. This union generally occurs in the neigh- 

 borhood of the lower border of the subscapularis, hence 

 the vein is from one to one and a half inches shorter than 

 the artery. The artery begins where the vein ends, i.e., 

 at the lower border of the first rib and is divided into 



