the functional breast
The breast is an apocrine gland that produces milk to feed an infant child; for which the nipple of the breast is centred in (surrounded by) an areola (nipple-areola complex, NAC), the
skin color of which varies from pink to dark brown, and has many sebaceous glands. The basic units of the breast are the terminal duct lobular units (TDLUs), which produce the
fatty breast milk. They give the breast its offspring-feeding functions as a mammary gland. They are distributed throughout the body of the breast; approximately two-thirds of the lactiferous tissue is within 30-mm of the base of the nipple. The terminal lactiferous ducts drain the milk from TDLUs into 4–
18 lactiferous ducts, which drain to the nipple; the milk-glands-to-
fat ratio is 2:1 in a lactating woman, and 1:1 in a non-lactating woman. In addition to the milk glands, the breast also is composed of connective tissues (collagen, elastin),
white fat, and the suspensory
Cooper's ligaments. Sensation in the breast is provided by the peripheral nervous
system innervation, by means of the
front (anterior) and side (lateral) cutaneous branches of the fourth-, the fifth-, and the sixth intercostal nerves, while the T-4 nerve (Thoracic spinal nerve 4), which innervates the dermatomic area, supplies sensation to the nipple-areola complex.
