The Mammae (Mammary Gland; Breasts). 



The mammae secrete the milk, and are accessory glands of the generative system. 

 They exist in the male as well as in the female; but in the former only in the rudi- 

 mentary state, unless their growth is excited by peculiar circumstances. In the 

 female they are two large hemispherical eminences lying within the superficial 

 fascia and situated on the front and sides of the chest; each extends from the second 

 rib above to the sixth rib below, and from the side of the sternum to near the mid- 

 axillary line. Their weight and dimensions differ at different periods of life, and 

 in different individuals. Before puberty they are of small size, but enlarge as the 

 generative organs become more completely developed. They increase during preg- 

 nancy and especially after delivery, and become atrophied in old age. The left 

 mamma is generally a little larger than the right. The deep surface of each is 

 nearly circular, flattened, or slightly concave, and has its long diameter directed 

 upward and lateralward toward the axilla; it is separated from the fascia covering 

 the Pectoralis major, Serratus anterior, and Obliquus externus abdominis by loose 

 connective tissue. The subcutaneous surface of the mamma is convex, and presents, 

 just below the center, a small conical prominence, the papilla. 



The Mammary Papilla or Nipple (papilla mamma} is a cylindrical or conical 

 eminence situated about the level of the fourth intercostal space. It is capable 

 of undergoing a sort of erection from mechanical excitement, a change mainly 

 due to the contraction of its muscular fibers. It is of a pink or brownish hue, its 

 surface wrinkled and provided with secondary papillae ; and it is perforated by from 

 fifteen to twenty orifices, the apertures of the lactiferous ducts. The base of the 

 mammary papilla is surrounded by an areola. In the virgin the areola is of a delicate 

 rosy hue; about the second month after impregnation it enlarges and acquires a 

 darker tinge, and as pregnancy advances it may assume a dark brown or even black 

 color. This color diminishes as soon as lactation is over, but is never entirely 

 lost throughout life. These changes in the color of the areola are of importance 

 in forming a conclusion in a case of suspected first pregnancy. Near the base of 

 the papilla, and upon the surface of the areola, are numerous large sebaceous glands, 

 the areolar glands, which become much enlarged during lactation, and present 

 the appearance of small tubercles beneath the skin. These glands secrete a pecu- 

 liar fatty substance, which serves as a protection to the integument of the papilla 

 during the act of sucking. The mammary papilla consists of numerous vessels, 

 intermixed with plain muscular fibers, which are principally arranged in a circular 

 manner around the base: some few fibers radiating from base to apex. 



Development. The mamma is developed partly from mesoderm and partly from 

 ectoderm its bloodvessels and connective tissue being derived from the former, its 

 cellular elements from the latter. Its first rudiment is seen about the third month, 

 in the form of a number of small inward projections of the ectoderm, which invade 

 the mesoderm; from these, secondary tracts of cellular elements radiate and sub- 

 ~r~ 1 -u to . !-. ,..- oe f n f v. s*V%Jwnj of tl te~ --Hiilar *..i"V<ji>-^, ^, and nearly 

 parallel with, each other. Together with the connecting skin between them, 

 they form the posterior labial commissure or posterior boundary of the pudendum. 

 The interval between the posterior commissure and the anus, from 2.5 to 3 cm. 

 in length, constitutes the perineum. The labia majora correspond to the scrotum 

 in the male. 



The Labia Minora (labia minora pudendi; nympha) are two small cutaneous 

 folds, situated between the labia majora, and extending from the clitoris obliquely 

 downward, lateralward, and backward for about 4 cm. on either side of the orifice 

 of the vagina, between which and the labia majora they end; in the virgin the pos- 

 terior ends of the labia minora are usually joined across the middle line by a fold 

 of skin, named the frenulum of the labia or fourchette. Anteriorly, each labium 

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