Upper -inner quadrant
Upper -inner quadrant
The breast is hormonally sensitive tissue, responsive to the changes of monthly cycling and aging. Glandular tissue, namely secretory tubu-loalveolar glands and ducts, forms 15 to 20 septated lobes radiating around the nipple. Within each lobe are many smaller lobules. These drain into milk-producing ducts and sinuses that open onto the surface of the areola, or nipple. Fibrous connective tissue provides structural support in the form of fibrous bands or suspensory ligaments connected to both the skin and the underlying fascia. Adipose tissue, or fat, surrounds the breast, predominantly in the superficial and peripheral areas. The proportions of these components vary with age, the general state of nutrition, pregnancy, exogenous hormone use, and other factors.
The surface of the areola has small, rounded elevations formed by sebaceous glands, sweat glands, and accessory areolar glands. A few hairs are often seen on the areola.
Both the nipple and the areola are well supplied with smooth muscle that contracts to express milk from the ductal system during breast-feeding. Rich sensory innervation, especially in the nipple, triggers "milk letdown" following neurohormonal stimulation from infant sucking. Tactile stimulation of the area, including the breast examination, makes the nipple smaller, firmer, and more erect, while the areola puckers and wrinkles. These normal smooth muscle reflexes should not be mistaken for signs of breast disease.
Occasionally, one or more extra or supernumerary nipples are located along the "milk line," illustrated on the right. Only a small nipple and areola are usually present, often mistaken for a common mole. There may be underlying glandular tissue. An extra nipple has no pathologic significance.
The male breast consists chiefly of a small nipple and areola. These overlie a thin disc of undeveloped breast tissue that may not be distinguishable clinically from the surrounding tissues. A firm button of breast tissue 2 cm or more in diameter has been described in roughly one out of three adult men. The limits of normal have not yet been clearly established.
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