Anatomy of the Breast

The types of breast tissue show up differently on mammograms.

A woman’s breast has two functional parts. The first is geared toward milk production. The second is supportive tissue that gives the breasts their look and feel.

Before puberty, there is a small amount of breast tissue, including milk ducts, in both boys and girls. During puberty, female hormones cause girls to develop additional breast tissue.

Milk Production

The parts of the breast involved in milk production are:

  • Nipple
  • Areola
  • Milk Ducts
  • Lobes
  • Lobules
A woman’s breast has two functional parts, one of which is geared toward milk production.

Each breast has 15-20 sections, or lobes, that branch out from the nipple and interconnect with each other, similar to a spider web. Each lobe contains numerous lobules, which contain milk producing glands. Lobules are linked together by tiny tubes called milk ducts. The milk ducts also store milk in enlarged areas and transport milk to the nipple. The areola contains glands that provide lubrication for the nipple during breast feeding.

Breast Support

The tissues in the breast that provide support and shape are:

  • Fat
  • Ligaments
  • Connective tissue
  • Pectoral muscle (chest muscle)
  • Blood vessels
  • Lymph nodes and vessels

The spaces between the lobules and ducts are filled with fat. There is no muscle in the breasts, but they are supported by the pectoral muscle, which lies over the rib cage. The breast also contains connective tissue that provides support and contains capillaries and other specialized cells. Ligaments that attach to the skin of the breast also provide support.

The breast contains two types of vessels, blood and lymph. Blood vessels supply nutrients to the breast tissue and carry away waste. Lymph vessels, which are found throughout the body, carry fluid called lymph which contains cells that help the body fight infection. Lymph vessels drain into lymph nodes, which are small, bean shaped glands. The lymph vessels in the breasts connect to lymph nodes that lie in the axilla (armpit), above the collarbone, and behind the sternum.

Illustration of Breast Anatomy

The following illustration shows some of the parts of the breast described above.

Diagram of the anatomy of the breast.

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