The female breast is a hemispheric projection of variable size positioned anterior to the pectoralis major and serratus anterior muscles. A fascia layer composed of dense, irregular connective tissue connects it to these muscles.

Each breast features a pigmented projection known as the nipple, through which milk emerges via closely spaced openings of ducts, referred to as lactiferous ducts. Surrounding the nipple is a circular pigmented area of skin named the areola, which appears rough due to the presence of modified sebaceous glands.

The breast is supported by connective tissue strands known as the suspensory ligaments of the breast or Cooper's ligaments, which extend between the skin and fascia. Within each breast lies a mammary gland, a modified sweat gland responsible for milk production. A mammary gland comprises 15 to 20 lobes separated by adipose tissue. Each lobe contains several smaller compartments known as lobules, housing grape-like clusters of milk-secreting glands, termed alveoli, embedded in connective tissue.

Myoepithelial cells surrounding the alveoli contract to propel the milk into secondary tubules and the mammary ducts during milk production. Near the nipple, these mammary ducts slightly expand to form sinuses, called lactiferous sinuses, where some milk may be stored before draining into a lactiferous duct.

Milk production is primarily stimulated by the hormone prolactin from the anterior pituitary, with additional contributions from progesterone and estrogens. The milk ejection is facilitated by oxytocin, released from the posterior pituitary in response to an infant's suckling on the mother's nipple.