PRACTICAL CONSIDERATIONS : MAMMARY GLANDS. 2033 



Variations. The mammae are frequently asymmetrically developed, the left being often 

 larger than the right. While very rarely one or both may be wanting, with or without associated 

 absence of the nipple, increase in their number is of relatively common occurrence. The super- 

 numerary mammae vary greatly in the extent to which they are developed, sometimes being 

 represented by well-formed accessory glands (polymastia) that may become functionating organs, 

 but more often, particularly in the male subject, by only rudimentary nipples (polythelia), or 

 even by pigmented areas suggesting areolae. In women polythelia is usually associated with 

 greater or less development of glandular tissue. Although the astonishing frequency (14 per 

 cent. ) of polythelia in men, as announced by Bardeleben, 1 is to be reconciled only by accepting 

 many doubtful pigment spots as of significance, the occurrence of rudimentary supernumerary 

 nipples in males is undoubtedly more common than formerly recognized. Exceptionally above 

 and to the outer side, the usual position of the accessory mammae is below and somewhat 

 medial to the normal glands, and in general corresponds to the mammary line of the lower 

 animals, The number of the accessory glands varies, as many as three pairs in one case, and 

 five milk-secreting organs in another, having been observed. They are often asymmetrically 

 placed and not uniformly developed. Comparative studies of the mammae in the lower animals 

 and the disposition of the supernumerary organs in the human subject, suggest the probability 

 that man's remote ancestors normally possessed a greater number than two, 2 the occasional 

 occurrence of the anomalous mammae indicating a reversion to the primary condition. In addi- 

 tion to the supernumerary mammas in positions anticipated by the milk-ridges, rudimentary 

 organs sometimes occupy very unusual situations, among which have been the back, shoulder, 

 thigh, and labium majus. Erratic mammae are also met with among the lower animals. 



PRACTICAL CONSIDERATIONS : THE MAMMARY GLANDS. 



The skin covering the breast is thin and movable, with plainly visible cutaneous 

 veins which enlarge during lactation, or in cases of mammary hypertrophy, or when 

 obstruction due to abscess or new growth exists in the breast or in the post-mam- 

 mary region. The frequent occurrence of asymmetry in size, the left breast being 

 larger, is said (Williams) probably to be due to the fact that most mothers, being 

 right-handed, suckle chiefly with the left breast, which is also said to be on an aver- 

 age heavier, more intimately associated with the pelvic sexual organs, more prone 

 to hypertrophy, and more likely to be the seat of carcinoma or other neoplasms. 

 The greater part of the breast lies upon the sheath of the pectoralis major muscle, 

 on which it is freely movable, the intervening cellular tissue being extremely lax. 

 About one-third of the gland, however, extends beyond and below the axillary 

 border of the pectoralis major, and is in relation in the axilla with the serratus mag- 

 nus and, when large, with the origins of the rectus and the external oblique. While 

 the normal breast moves freely over the pectoral muscle, it also moves slightly with 

 it when the muscle is contracted. Hence in inflammation of the breast, or after 

 operation upon it or for its removal, the muscle should be kept at rest by binding 

 the arm to the side. In testing for pathological adhesion of the breast to the pec- 

 toral sheath, it is well to move the breast in the direction of the fibres of the pecto- 

 ralis major. If it is moved transversely to them, it may carry the relaxed muscle 

 with it and no diminution of mobility will be noticeable. 



In examining for growths of the breast, the normal lobes, especially if at all 

 enlarged, may be felt through the adipose envelope and may be mistaken for tumors. 

 To avoid this, the gland should be palpated with the flat hand, which should gently 

 compress it against the chest wall. In this manner very small cysts or neoplasms 

 may be recognized, as they become more resistant and more prominent than the 

 normal gland tissue. The two breasts should be thus examined at the same time, 

 so that any difference in their size, consistence, or sensitiveness may be detected. 



The nipple in men and in young virgins is found over the fourth intercostal 

 space, or over the fifth rib, about three-quarters of an inch external to the costo- 

 chondral junction. In older women its position is not constant, and, of course, it 

 varies with the degree of the enlargement, laxness, and pendency that follow preg- 

 nancy and that are common in women of tropical lands and in negresses and women 

 of other of the lower races. 



The development of the nipple may be arrested at the stage when the central 

 part of the ectoblastic ingrowth has undergone degeneration and when a depression 



1 Anatom. Anzeiger, Bd. vii., 1892. 



2 An interesting review of the subject is given by Bonnet in Ergebrisse d. Anat. n. Entwick., 

 Bd. ii., 1892. 



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