io THE UPPER EXTREMITY 



internal mammary artery, may be traced into the mamma; 

 and other vessels, called the external mammary branches of 

 the lateral thoracic artery, may be seen winding round the 

 edge of the pectoralis major, or piercing its lower fibres, to 

 reach the gland. 



By means of lymphatic vessels the mamma is brought into 

 connection with the sternal lymph glands, and also, more 

 directly, with the axillary lymph glands. The latter con- 

 nection is one of much importance to the surgeon in cases 

 where it is necessary to remove the organ for malignant 

 disease. 



In the male the mamma (mamma virilis) is extremely 

 rudimentary. The nipple is small and pointed, and the 

 areola is surrounded by sparse hairs. 



Deep Fascia. The deep fascia of the pectoral region is 

 a thin membrane which closely invests the pectoralis major. 

 It is attached above to the clavicle, and medially to the 

 front of the sternum. Below, it is continuous with the deep 

 fascia covering the abdominal muscles, and, at the lower 

 border of the pectoralis major muscle, it is continuous with 

 the axillary fascia. At the deltopectoral triangle a process 

 from its deep surface dips in between the deltoid and 

 pectoralis major muscles to join the costo-coracoid membrane, 

 whilst, further laterally, the aponeurosis becomes continuous 

 with the fascia covering the deltoid muscle. The costo- 

 coracoid membrane will be described later on. 



Fascia Axillaris (Axillary Fascia). The axillary fascia is 

 a dense felted membrane which extends across the base of 

 the axilla. It is continuous anteriorly with the deep fascia 

 over the pectoralis major, posteriorly with the fascial sheaths 

 of the latissimus dorsi and the teres major muscle, medially 

 with the deep fascia on the surface of the serratus anterior, 

 whilst laterally it is continuous with the deep fascia on 

 the medial surface of the upper part of the arm. It is 

 drawn up towards the hollow of the axilla, and the 

 elevation is due chiefly to the connection of its deep surface 

 with the fascial sheath of the pectoralis minor, and partly 

 to its attachment to the areolar tissue which fills the axillary 

 space. In a well- injected subject a small artery, from the 

 lower part of the axillary trunk, may be seen ramifying on 

 the surface of the fascia. 



Dissection. The pectoralis major muscle must now be cleaned, and its 



