PRACTICAL ANATOMY. 



limited by the humerus ; internally, by the upper four or 

 five ribs covered by the serrate muscle ; the apex is 

 above, and corresponds to the entrance of the axillary 

 vessels and the brachial plexus of nerves. When the 

 arm is placed at rig-lit angles to the trunk, the axilla, 

 limited by the prominent lower anterior and posterior 

 borders, is seen to be a marked concavity, narrower ex- 

 ternally than internally. The skin is rather closely ad- 

 herent, covered by a growth of short hair. Numerous 

 sebaceous follicles, secreting an unctious, highly-odorous 

 fluid, and sweat-follicles, are imbedded in the skin in 

 this region. When the skin is removed the superficial 

 fascia is seen. It is loaded with fat, as a rule, and pre- 

 sents some superficial veins, nerves, and lymphatics. 

 The deep fascia is aponeurotic, and incloses the deeper 

 structures. An incision should be made through the 

 pectoralis major and minor, through the layer of cellular 

 fascia beneath the pectoralis minor, and these structures 

 turned aside. There will now be exposed the axillary 

 vein and artery and their branches, the brachial plexus 

 and its branches, and a cluster of lymphatic glands im- 

 bedded in a quantity of loose fat. The axillary vein lies 

 in front of the artery ; it is the continuation of the basi- 

 lic vein, and receives the vena comites, numerous small 

 branches, and the cephalic. The axillary artery is the 

 continuation of the subclavian ; it lies behind and to the 

 outer side of the vein ; they are invested with a quantity 

 of loose cellular tissue. The larger branches of the ax- 

 illary artery are the long thoracic, which is often con- 

 cealed behind the lower border of the pectoralis major ; 

 the subscapular, which runs down the anterior surface 

 of the subscapular muscle ; the circumflex, external and 

 internal, distributed to the neck of the humerus. The 



