Breast Anatomy

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Breast facts

  • The breasts are medically known as the mammary glands.
  • The mammary glands are made up of lobules, milk-producing glandular structures, and a system of ducts that transport milk.
  • Lymphatic vessels in the breast drain excess fluid.
  • Breast growth begins at puberty in humans, in contrast to other types of primates in which breasts enlarge only during lactation.
  • Breast tissue develops in the fetus along the so-called "milk lines," extending from the armpit to the groin.

What are the breasts (mammary glands)?

The breasts, located on the front of the chest, are medically known as the mammary glands. The term "breast" is sometimes used to refer to the area at front of the chest.

What are the anatomical features of the breast?

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The mammary gland is made up of lobules, glandular structures that produce milk in females when stimulated to do so. The lobules drain into a system of ducts, connecting channels that transport the milk to the nipple. Between the glandular tissue and ducts, the breast contains fat tissue and connective tissue.

Both males and females have breasts; the structure of the male breast is nearly identical to that of the female breast, except that the male breast tissue lacks the specialized lobules, as there is no physiologic need for milk production by the male breast. Abnormal enlargement of the male breasts is medically known as gynecomastia.

The breast does not contain muscles. Breast tissue is located on top of the muscles of the chest wall. Blood vessels and lymphatic vessels (a system of vessels that drains fluid) are located throughout the breast. The lymphatic vessels in the breast drain to the lymph nodes in the underarm area (axilla) and behind the breast bone (sternum).

In females, milk exits the breast at the nipple, which is surrounded by a darkened area of skin called the areola. The areola contains small, modified sweat glands known as Montgomery's glands. These glands secrete fluid that serves to lubricate the nipple during breastfeeding.

Picture of the anatomy of the breast
Picture of the anatomy of the breast

Medically Reviewed by a Doctor on 3/11/2014

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Breast Anatomy - Pregnancy Question: What changes did you experience with your breasts during pregnancy and while breastfeeding?
Breast Anatomy - Medical Conditions Question: What medical conditions have you experienced that involve your breasts?
Breast Anatomy - Gynecomastia Question: Please describe your experience with gynecomastia.
The breast is medically referred to as the mammary gland. Common medical concerns about the breast include breast cancer, breast lumps, and breast infection

Families with Breast Cancer

Ms. G. is a 40-year-old woman with two small children. Like most women, she is concerned about her chances of developing breast cancer. She asks her doctor about her risks. Although breast cancer is a worry for most women, Ms. G. is especially worried because of a family history of breast cancer. Her mother and sister had breast cancers that were diagnosed at young ages.