264 



APPLIED ANATOMY. 



involved and the anterior or thoracic set escape. This has already been alluded to 

 in the section on the mammary gland (see page 184). These three sets drain into 

 the subclavian nodes and then empty into the subclavian vein near its junction with 

 the jugular. 



Abscess of the Axilla. Pus forms in the axillary region from ordinary pyo- 

 genic organisms which may or may not be associated with specific organisms like 

 the tubercle bacillus. Abscesses may be either superficial or deep. 



The skin of the axilla is thin, loose, and abundantly supplied with sebaceous 

 glands connected with the hair-follicles and sweat-glands. These glands are in the 

 deeper layer of the skin and are superficial to the axillary fascia, hence abscesses 

 originating from them tend to break externally; usually they do not become large 

 nor extend deep into the axilla. 



Abscesses originating from the lymphatics, on the contrary, may be either deep in 

 the axilla along the axillary, pectoral, or subscapular vessels, or they may be in the 

 axillary fat and tend to point toward the skin. If the lymphatics along the axillary 

 vessels are the point of origin, the abscess may follow them down under the deep 

 fascia to the elbow. If the nodes high up are involved, the abscess may work up 

 under the clavicle into the neck. If, however, the nodes near the apex of the axilla 



FIG. 276. Subpectoral abscess. 



form the starting-point then the abscess bulges through the cribriform portion of the 

 axillary fascia (between the " Armbogen " and " Achselbogen " ) into the axilla 

 and tends to discharge through the skin. Abscesses originating in the pectoral 

 group of lymphatics point at the lower margin of the anterior axillary fold. The 

 attachment of the serratus anterior to the side of the chest prevents them from work- 

 ing towards the back. 



Abscesses involving the subclavian nodes may cause a subpectoral abscess (Fig. 

 276). The pus collects superficial to the costocoracoid membrane and clavipectoral 

 fascia and pushes the pectoralis major muscle outward, forming a large rounded 

 prominence below the inner half of the clavicle. The pus cannot extend upward or 

 toward the median line on account of the attachment of the pectoralis major muscle. 

 It can burrow through the intercostal spaces and involve the pleural cavity, or break 

 through the fibres of the pectoralis major anteriorly or between the pectoralis major 

 and deltoid, or, as is most commonly the case, work its way under the pectoralis 

 major muscle, over the pectoralis minor, until it reaches the border of the pectoralis 

 major at the anterior fold of the axilla. 



In emptying these abscesses an incision is to be made along the anterior axillary 

 fold and a tube introduced beneath the pectoralis major. 



Incision for Axillary Abscess. In opening an axillary abscess one should bear in 

 mind that the important veins and nerves accompany the arteries and that the arteries 

 lie in three places, viz. , externally along the humerus, anteriorly along the edge of the 

 pectoral muscles, and posteriorly along the edge of the scapula; therefore these three 

 localities are to be avoided and an incision made in the middle of the axilla and short 

 enough not to endanger the brachial vessels on the outside or the long thoracic or 

 subscapular on the inside near the chest-wall. 



The incision may divide the skin and if desired the deeper structures can be 

 parted by introducing a closed haemostatic forceps and separating its jaws. 



