You and I have breasts, but that doesn’t mean we really understand how they work! I don’t remember learning much about breasts in high school biology (it would have been mortifying in a co-ed school).

It is important to understand the anatomy of the breast so that you can understand what’s involved in breast reduction surgery. Let’s find out a little more about these amazing mammary glands.

Mammary Glands

Breasts, also known as mammary glands, are only found in mammals – thus why they are called mammary glands. They are an exocrine gland that produces milk to feed offspring. In humans, the mammary glands take the form of breasts. In cows, deer, and goats, they take the form of udders. And in dogs and cats, mammary glands are known as dugs. Of course, we are only interested in human breasts here.

Mammal embryos start out along a continuum of development pathway that has the potential to produce male or female anatomy. As the embryo grows, sex-specific hormones are produced and determine whether the embryo becomes a male or a female. A female embryo will develop female sex organs, including breast glands.

Glandular tissue has 15 to 20 sections called lobes that branch out from the nipple. Each lobe is made up of smaller structures, called lobules that produce milk when a woman is lactating. Each lobule holds tiny, hollow sacs called alveoli. When breastfeeding, milk travels through a network of tiny tubes called ducts from the alveoli. These ducts connect and join together into larger ducts. The larger ducts then connect to the nipple and allow milk to exit.

Spaces around the lobules and ducts are filled with fat, ligaments and connective tissue. Ligaments and connective tissue provide support to the breast and give it shape.

Sensation in the breast occurs via nerves. Oxygen and nutrients travel to breast tissue through the blood in your arteries and capillaries (thin, fragile blood vessels).

The breast structure also includes the lymphatic system, which is a network of lymph nodes and lymph ducts that help fight infection. Lymph nodes are found under the armpit, above the collarbone, behind the breastbone and in other parts of the body. They trap harmful substances that may be in the lymphatic system and safely drain them from the body.

The breast has no muscle, except for some tiny muscles in the nipple.  There is muscle between the breast and your rib cage.

The dark area around the nipple, as you probably know, is the areola. The purpose of the areola is two-fold: it helps support the nipple, and it contains Montgomery’s glands which keep the nipple moisturized during breastfeeding.

Nearly all women have the same milk-producing structures within their breasts. As you know, women’s breast tissue is sensitive to cyclic changes in hormone levels, and that is why women often experience sore and tender breasts just before and during menstruation.

Your breasts change over the course of your life. They may get bigger during pregnancy. They will often get smaller when you lose weight and increase in size when you gain weight.