1446 SUKFACE AND SUKGICAL ANATOMY. 



THE AXILLA. 



The anterior fold of the axilla, formed by the inferior border of the pectoralis 

 major, extends from the fifth rib to the middle of the anterior border of the deltoid. 

 With the arm abducted, the interval between the sternal and clavicular fibres of 

 the pectoralis major is indicated by a slight groove extending distally and 

 laterally from the medial end of the clavicle. The sternal fibres, along with the 

 pectoralis minor, are removed in a complete operation for malignant disease of the 

 breast, the pectoral branches of the thoraco-acromial artery being secured as they 

 cross the interval between the sternal and clavicular portions of the greater pectoral. 

 The posterior fold of the axilla, formed by the latissimus dorsi and the teres major 

 muscles, is on a lower level than the anterior fold, and leaves the chest a little in 

 front of the inferior angle of the scapula. Between the two folds, and running in 

 the long axis of the limb, from the axilla to the middle of the arm, is the prominence 

 of the coraco-brachialis muscle. The pulsations of the third part of the axillary 

 artery may be felt in the furrow, immediately behind this prominence, at the 

 junction of the anterior and middle thirds of the lateral wall of the axilla. 



Female Mamma. The breast tissue proper is arranged to form a central 

 portion, the corpus mammae, and a peripheral portion, made up of branching 

 processes which radiate into the paramammary fat and become continuous 

 ultimately with the connective tissue septa of the subcutaneous fatty tissue. The 

 mamma, therefore, has no distinct capsule. In the young adult nullipara, the 

 corpus mammae is compact and well defined, and contains but little intramammary 

 fat, while the peripheral processes are relatively small. In multipara, the corpus 

 mammas contains more fat, and the peripheral processes extend more widely into 

 the paramammary fat. 



The arrangement and extent of the parenchyma can be well seen by treating the breast with 

 a 5 per cent, solution of nitric acid. If slices of the fresh organ are placed in this solution for a 

 few minutes and then washed under running water, the albumen of the epithelial cells of the 

 parenchyma is coagulated, while the connective tissue is rendered translucent and somewhat 

 gelatinous. The ultimate lobules of the parenchyma now appear as little (1 to 2 mm.), dull, opaque, 

 white, sago-like bodies, arranged in grape-like clusters around the finer branches of the ducts. 



The parenchyma is prolonged into the peripheral processes, into the suspensory 

 ligaments of Cooper, and into the loose retromammary cellular tissue and pectoral 

 fascia. The breast tissue, therefore, has a much wider distribution than was 

 formerly supposed. Vertically, it extends from the second rib to the sixth costal 

 cartilage at the angle where it begins to ascend towards the sternum ; horizontally, 

 from a little medial to the lateral border of the sternum, opposite the fourth rib, to 

 the fifth rib in the mid-axillary line. The medial hemisphere of the mamma rests 

 almost entirely on the pectoralis major ; at its lowest part it slightly overlies the 

 upper part of the aponeurosis covering the rectus abdominis muscle. The superior 

 quadrant of the lateral hemisphere rests upon the greater pectoral, on the edge of 

 the lesser pectoral, and to a slight extent on the serratus anterior, upon which 

 it extends upwards into the axilla as high as the third rib, where it comes into 

 relation with the thoracic group of axillary lymph glands. The remainder of the 

 lateral hemisphere rests almost entirely upon the serratus anterior, except the 

 lowest part, which overlaps the digitations of the external oblique arising from 

 the fifth and sixth ribs. It follows, therefore, that fully one-third of the whole 

 mamma lies inferior and lateral to the axillary border of the pectoralis major 

 muscle. The surgeon must cut beyond the above limits if he wishes to remove the 

 whole of the mammary tissue. 



The axillary fascia resists the spontaneous rupture of an axillary abscess, which, 

 therefore, tends to spread upwards beneath the pectorals, and towards the root of the 

 neck. To open the abscess the incision should be made upon the medial wall, behind, 

 and parallel to, the lateral thoracic artery, which runs under cover of the anterior fold. 



The axillary lymph glands vary greatly in size and number ; many are no larger than 

 a pin's head. In the female some of them undergo an adipose functional involution, 

 whereby they come to resemble fat lobules. In health, one or two glands can usually be 

 felt by thrusting the fingers upwards and medially beneath the anterior fold, the arm 



