The breasts of an adult woman are milk-producing, tear-shaped glands. They are supported by and attached to the front of the chest wall on either side of the breast bone or sternum by ligaments. They rest on the major chest muscle, the pectoralis major.
The breast has no muscle tissue. A layer of fat surrounds the glands and extends throughout the breast.
The breast is responsive to a complex interplay of hormones that cause the tissue to develop, enlarge and produce milk. The three major hormones affecting the breast are estrogen, progesterone and prolactin, which cause glandular tissue in the breast and the uterus to change during the menstrual cycle.
Each breast contains 15 to 20 lobes arranged in a circular fashion. The fat (subcutaneous adipose tissue) that covers the lobes gives the breast its size and shape. Each lobe is comprised of many lobules, at the end of which are tiny bulb like glands, or sacs, where milk is produced in response to hormonal signals.
Ducts connect the lobes, lobules, and glands in nursing mothers. These ducts deliver milk to openings in the nipple. The areola is the darker-pigmented area around the nipple.
Quadrants of the Breast
Note: C50.6 is the code for axillary tail or tail of breast.
Regional Lymph Nodes
Blood and lymph vessels form a network throughout each breast. Breast tissue is drained by lymphatic vessels that lead to axillary nodes (which lie in the axilla) and internal mammary nodes (which lie along each side of the breast bone). When breast cancer spreads, it is frequently to these nodes.
2 Axillary lymphatic plexus
4 Cubital lymph nodes *
5 Superficial axillary (low axillary)
6 Deep axillary lymph nodes
7 Brachial axillary lymph nodes
8 Interpectoral axillary lymph nodes (Rotter nodes)
10 Paramammary or intramammary lymph nodes
11 Parasternal lymph nodes (internal mammary nodes)
* Note: the cubital lymph nodes are not part of the lymph node drainage of the breast.