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THE BREAST

BIG PICTURE

The functional component of the breast is the mammary gland, which synthesizes, secretes, and delivers milk to the newborn. It is only during a pregnancy that the mammary glands reach a mature state of development by way of circulating female hormones. Both men and women have breasts but the male mammary glands do not develop under normal circumstances. Lobules within mammary glands produce milk and the lactiferous ducts transport the milk into openings in the nipples. Branches of the internal thoracic, axillary, and intercostal arteries supply the mammary glands. Lymph from the mammary glands primarily drains into axillary lymph nodes, and also into the pectoral, clavicular, and parasternal nodes.

MAMMARY GLAND STRUCTURE

The mammary gland is located within the superficial fascia and is surrounded by a variable amount of adipose tissue. The breast overlies the pectoralis major and serratus anterior muscles on ribs 2–6 (Figure 2-1A and B).

  • Lobules. Each mammary gland consists of 15 to 20 radially aligned lobes of glandular tissue, which synthesizes and produces milk; each lobe has a lactiferous duct that opens onto the surface of the nipple.

  • Nipple. The nipple is positioned on the anterior surface of the breast and is surrounded by a circular hyperpigmented region called the areola; small collections of smooth muscle at the base may cause erection of the nipple when breast-feeding or when sexually aroused.

  • Suspensory (Cooper's) ligaments. Bands of fibrous connective tissue that support the breast and maintain its normal shape; the fibrous bands course from the deep fascia, through the breast tissue, and terminate in the dermis.

  • Retromammary space. A layer of loose connective tissue that separates the breast from the deep fascia overlying the pectoralis major and serratus anterior muscles.

  • Axillary tail. Mammary gland tissue that extends along the inferior border of the pectoralis major muscle into the axilla.

Figure 2-1:

A. Breast surface anatomy. B. Sagittal section of the breast. C. Arterial supply of the breast. D. Lymphatic drainage of the breast.

Image not available. Breast cancer. Breast cancer is cancer that arises from breast tissue. The phrase “adenocarcinoma of the breast” can be thought of as an overarching term for breast cancer because “adeno” refers to “glands” and “carcinoma” refers to “cancer.” The breast is primarily composed of the glandular tissue (lactiferous ducts or lobules of the mammary gland). Breast adenocarcinomas are classified as either noninvasive (referred to as ductal carcinoma in situ or DCIS) or invasive. DCIS tumors are abnormal epithelial cells that remain contained in the mammary gland. Invasive tumors spread from the original site (either lactiferous ducts or lobules) into the lymphatic system and could travel to downstream lymph nodes (often axillary nodes). Inflammatory carcinoma of the mammary gland is a very rare but aggressive disease whereby neoplastic ...

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