192 



PRACTICAL ANATOMY. 



THE AXILLA, OR AXILLARY SPACE. 



The axilla, or axillary space, is of interest anatomically because important 

 surgical operations are performed here. Armpit and axilla are not synonymous 

 terms. The physician places a clinical thermometer in the armpit not in the 

 axilla. The axillary lymphatic glands become secondarily enlarged in cases of 

 infection, and may require extirpation. The head of the humerus may become 

 dislocated into the axilla and require reduction. Pus may form in the neck and 

 find its way to the axilla and make its liberation incumbent. A wound of the 

 axillary artery makes its ligation a necessity. Amputation at the shoulder-joint 

 is sometimes done. 



The apex of the axilla or inlet has bony boundaries: (i) The outer surface of 

 the first rib ; (2) the clavicle ; (3) the superior costa or superior border of the scapula. 

 It is by the apex that this space communicates with the thorax and neck. 



Upper part of 

 serratus magnuc 



Middle part 



Lower part 



FIG. 135. SERRATUS MAGNUS. THE INNER \\AI.I OF THE AXII.I.A. 



The base of the axilla is formed by the skin, the superficial and the deep 

 fascia. The deep fascia in this locality is known specifically as axillary fascia ; 

 it is also called suspensory fascia. The deep fascia is a derivative of the third 

 layer of the deep cervical fascia, passing under the clavicle. In front it is con- 

 tinuous with the pectoral fascia; behind, with the fascia covering the latissimus 

 dorsi muscle. 



The anterior boundary is formed by the skin, fascia:, pectorales major and 

 minor muscles, and clavi-pectoral fascia. This boundary is very well defined. 



The posterior boundary is formed by the subscapularis, the teres major, and 

 latissimus dorsi muscles. 



