The breasts are glands that can make milk. Each breast sits on chest muscles that cover the ribs.
Each breast is divided into 15 to 20 sections called lobes. Lobes contain many smaller lobules. Lobules contain groups of tiny glands that can produce milk. Milk flows from the lobules through thin tubes called ducts to the nipple. The nipple is in the center of a dark area of skin called the areola. Fat fills the spaces between the lobules and ducts.
The breasts also contain lymph vessels, which carry a clear fluid called lymph. The lymph vessels lead to small, round organs called lymph nodes. Groups of lymph nodes are found near the breast in the axilla (underarm), above the collarbone, in the chest behind the breastbone, and in many other parts of the body. The lymph nodes trap bacteria, cancer cells, or other harmful substances that may be in the lymphatic system.
