If you are thinking about getting silicone or saline implants for breast augmentation or breast reconstruction, having a basic understanding of the anatomy of the breast can be helpful when discussing your goals with your surgeon.

Inside the Breasts

Each breast is composed of fifteen to twenty lobes that circle the nipple in an arrangement comparable to the petals of a flower.  The lobes are made up of smaller sections called lobules; each lobule ends in numerous small structures (alveoli) that are involved in the production of milk.  All of these are joined together by the network of ducts, which function like tiny tubes.  In women who are nursing a baby, the ducts transport milk to the areola.  Once the ducts have reached this darkly colored skin, they merge with other ducts, and milk is passed through the nipple (Read more about Breastfeeding With Implants).  Although breast tissue is usually contained in the breast area, its exact location varies by person.  It is for this reason that elective mastectomies to reduce the risk of breast cancer are not always successful; some people may have breast tissue near the armpit, collarbone, or abdominal wall that is not detected during prophylactic surgeries.

Outside the Breasts

The skin that covers the breast falls into one of three types: regular skin, the areola, and the nipple.  The areola is the skin around the nipple that is darker in color than regular skin. Because the coloration of the areola is similar to that of a healing scar, the areolar incision is popular among women who decide to get implants (Read more about the advantages and disadvantages of different Incisions).

Tissue Structures That Surround the Breasts and Determine Their Size and Density

Any space surrounding the ducts and lobules is filled by ligaments, connective tissue, or fat (adipose tissue).  The size of a woman’s breasts is primarily determined by the amount of fat contained therein and not by the number of structures that produce milk.  In fact, these milk structures are very similar in the majority of women.  As women age, their breasts may decrease in density and increase in fat, especially after menopause. 

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Muscles Near the Breasts

The breasts themselves contain no muscle tissue.  Rather, breast tissue lies on top of the pectoralis major muscles.  These muscles separate the breasts from the rib cage.  Implants may be placed above, under, or partially under the pectoral muscle (Read more about the advantages and disadvantages of different Implant Placements).

Blood Vessels and Other Structures

Larger arteries can be found below the breast and meet smaller blood vessels near the breast. These thin blood vessels, called capillaries, run throughout each breast and supply the tissues with nutrients and oxygen.  The breasts also contain a network of lymph ducts, which transport lymph from the lymph nodes to the breast tissues to aid in fighting disease.  The lymph nodes, which resemble beans in shape, are located behind the breastbone (in the chest), in the armpit, and near the collarbone among other areas of the body.