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Anatomy of the Breast
~ Overview ~

Refer to the Anatomical Drawings for specific anatomical features mentioned below.

en and woman have breasts. Just about anything that you will find in a female breast will be found in a male breast, but some of the components will be undeveloped in the male. Neither men, prepubescent boys nor pubescent males expect to see any breast development on their bodies, unless they put on a lot of fatty deposits or they build up some fantastic "pecs" in the weight room. Large pecs are the result of muscular development behind the breast (pectoralis major and pectoralis minor muscles), and should not be confused with breast development. Women that do exercises to increase their breast size merely increase the pectoral muscle size, which makes their chest wall measurement (above the breasts) larger. Their cup size does not increase, but could actually decrease if they work really hard developing those pecs. Exercising muscles to develop them requires energy that may come from the burning of fatty deposits stored in the body, and those deposits may be those stored in the breasts.

When babies (males and females both) are only about three days old, a secretion called "witch's milk" may be expressed from the breast. This is thought by some experts to be caused by the excessive hormones in the mother's blood just before she gave birth. They were in her blood to allow her to produce milk. The fetus does not share the mother's blood while it is inside her uterus, but hormones, vitamins, minerals, etc. will pass through the placenta and umbilical cord to the fetus. Females may secrete a small amount of fluid from their nipples anytime after their breasts mature (and she is not pregnant or lactating). Be alarmed only if there is a sudden change in amount expressed, or its color changes (or becomes red), or if one side suddenly is different than the other side.

About 85 percent of the males will have some breast swelling during their puberty. This panics the males, and causes some concern to their parents as well. This is usually a temporary situation that seldom exists for more than a year or two. A call to his doctor should alleviate any concerns that anyone may have. Some medications may cause male breast growth, so check medication specification charts for "causes gynecomastia" (-mastia means "breasts" and gyneco- means "of a woman"). Gynecomastia caused by medications is usually temporary, but it can also come in a man's later years due to his hormonal changes.

Males should be just as aware of their breasts as females should be of theirs. Males can get breast cancer. Any unusual changes to the skin or the interior of the breast or emissions from the nipple should be quickly brought to the attention of their doctor.

A woman's breasts will produce colostrum for the first several days after delivery of a child. This is a type of pre-milk, and "true" breast milk will follow that. See our section on Breastfeeding for further information about the production of breast milk and breastfeeding. Some men actually have successfully produced breast milk. With help from hormones, herbs and/or a lengthy process of physically "encouraging" the production of milk, men (as well as non-parous (never pregnant) women) have purposely brought themselves to lactate, but it is relatively rare.

The American Cancer Society considers the human breast to be that area delineated by a perimeter line traced from the center of the sternum (breast bone) downward to the "bra line" (under the breasts), across to the side of (and half-way around) the body, up to the center of the armpit (axilla), across toward the neck to the clavicle ( collar bone), following the bone down the top of the sternum (breast bone). This entire area contains some breast tissue, which could sustain breast cancer growth or lymphatic node enlargement and should always be carefully checked when doing a Breast Self Examination.

The outside of the breast consists of the skin, the areola, and the nipple (we have some images of what might be seen here.) There also are body hairs on the breast, and they may be especially prominent in the areolar area. These do not indicate that the lady is masculine. Their presence is normal, and their number and color are controlled in the same manner as any other genetic characteristic is controlled. Genetic codes predetermine the amount of hair on the breasts, as well as their color, denseness and strength. Some "experts" tell us that the hairs should not be pulled, due to the chance of causing infections. Other "experts" tell us to use a depilatory cream, but that we should take care first to be certain that it will not irritate the sensitive nipple and areolar skin. Others advise us to bleach them so that they are less noticeable, while some go ahead and tell us to pull them out with tweezers. Be very careful with any method or material you might use. Some people simply leave them alone. Check with your doctor, and decide for yourself which method you prefer. (Personally, I would avoid the razor that some have chosen (ouch).)

The areola is the area of skin that surrounds the nipple. It is usually a different color than the skin on the breast itself, and may vary from slightly lighter than the breast skin to a very darků nearly black. The color is usually determined by the color of the body skin, or the ethnicity of the person, and it will change during a person's lifetime. As women sexually mature and also when they become pregnant, the areolae usually darken. After breastfeeding is completed, they may return to nearly the same color as before the pregnancy. Their size can be as small as an inch across to several inches wide. They may even be wide enough to cover half the breast, although this is unusual. They will get wider during pregnancy, partly because the breast itself is temporarily enlarging.

A number of small bumps that surround the nipple and look like "goose bumps" are sebaceous glands, and are called Montgomery's Glands or Areolar Glands. They secrete an oily substance that lubricates and conditions the surface of the nipple and the areola. This is helpful during breastfeeding, to prevent cracking of the nipple. These Montgomery's Glands become erect in the same manner that the nipple does when it is stimulated by touch, cold, fear, sexual stimulation, etc. Very small smooth-muscle tissues cause them to become more prominent (erect). This also causes the areolae to become narrower, but sexual stimulation will temporarily expand the whole breast.

Unlike a baby's bottle, a real nipple has more than one hole, or port (duct). It actually may have as many as 5 to 25 pores, usually one for each lobule in the breast. Nipples may be classified by their shape. If they come forward from the breast, they are considered to be prominent. They may also be flat, where they seem to be at the same level as the areola. Sometimes they may actually be depressed into the breast. These are referred to as "inverted" nipples. Be aware of how they are and pay close attention when you do a Breast Self Exam. Any way that they are is okay, but be concerned if they CHANGE. Check out the Breast Self Exam selection for more information on this matter. No matter what the nipple is like (flat, inverted or prominent), the shape will not prevent you from breast feeding your child.

People naturally focus on the nipple, and people that pierce or otherwise abuse their bodies are no exception. Carefully consider the circumstances of piercing the nipple before you do it. Remember that the 5 to 25 ducts that come through that nipple will be compromised by a wound that goes through them sideways. Consider waiting until after your breastfeeding years to do the piercing. Piercing can often damage the milk ducts and they may never be able to be opened. That will allow the associated gland lobules to not be able to produce milk, sometimes causing painful mastitis. Some nipples are exceptionally wide and some are exceptionally long, and some people attempt to modify their appearance by using various pieces of "jewelry" that stretches them or enlarges them. Use care and common sense when making decisions about modifying your body.

Parenchyma is the term that describes breast tissue that is involved in the production or transporting of breast milk. This includes the lobules, which are the glands in which the milk is actually produced from the mother's blood. This will give you a view of the inside of the breast, and this gives you a closer look behind the nipple. Sometimes referred to as alveoli or acini, the lobules are clustered at the terminus of the ducts in a way that resembles grapes on the vine. When the brain signals the lobules to produce milk, it is gathered together by the lactiferous ducts and brought to the nipple area, with a small "reserve" amount filling the ampullae (lactiferous sinus) just behind the nipple. About two-thirds of the average pre-menopausal breast is Parenchymal tissues. The amount of this tissue that is in the breast will not change when the person gains or loses weight but the amount of fatty tissue in the breast will change. The size of the breast will not necessarily determine the quantity of milk that a woman will produce. Smaller sized breasts are usually as successful at breastfeeding as larger breasts. When a woman is pregnant (or she takes other steps to cause her breasts to lactate), the lobules develop to the point that they can produce milk. That is why the breast enlarges during pregnancy, and is the reason women (and also men) do not normally produce milk until they have gone through a pregnancy.

Just before each lactiferous duct reaches the nipple, it swells out a little, creating what is called an ampulla (lactiferous sinus). This is the only part of the breast that actually holds a reserve of milk. This milk provides an enticement to the infant, to keep it at the nipple, while the lobules start the production of more milk. The ampullae are what need to be compressed when an infant (or the woman herself) wants to express milk from the breast. The infant offers a little assistance by adding suction.

Parenchyma, and a little of the stroma (non-milk bearing tissue) make up the density (or the firmness) of the breast. At about the age of 35 years, the breast becomes a little less dense. This is why mammograms are not usually done until after that age. Dense breast tissue makes it difficult to see signs of breast cancer on an x-ray film.

Stroma is the term used for breast tissue that does not deal with milk production. Muscle tissue, connective (Cooper's) ligaments and fatty tissue are included in this category. We need to understand that there is nearly NO MUSCLE TISSUE in the breast. Exercise develops the size of a muscle, but it will not increase the size of the breast, because there are no muscles to develop. The pectoral muscles BEHIND the breasts can be developed, which might push the breasts forward a little more, if the muscles are developed extensively. That much exercise, however, may result in the loss of body fat, and some of it may come from the breasts, making the breasts smaller than they were before the exercise program began. The exercise may be very healthy for you, though. There are some very minute muscles in the areola that cause an erection of the nipple and the Montgomery's glands. There are some tiny muscles around the lobules that help to express the milk, but there are no other muscles in the breast.

We all know what the fatty tissue does. It makes things bigger. The average sized breast of a pre-menopausal woman is about one-third fatty tissue. Larger breasts usually only have more fatty tissue, but not more lobular tissue. Fatty tissue helps to fill out the voids and lumps of our bodies, and so it helps us to look softer, and smoother. The average woman has a higher percentage of body fat than the average male, so she will usually have a more rounded softness to her body, softer in appearance as well as touch.

Inside the breast, connecting the back-side of the breast skin to the pectoral muscles, are ligaments that make up what is called connective tissue. The ligaments and connective tissue are called Cooper's Ligaments, or Suspensory Ligaments. Their purpose is to provide the shape of the breast. They pull in on the skin, while the fatty tissue and the Lobules press outward. There are controversies that surround these ligaments and their function, and they bring about many questions. In the Awareness selection, we address some of them, including the actual function of a bra during the many stages of a woman's life.

This takes you to six different galleries of images that show you breast details, such as Large & Dark Areolae, Tubular Breasts, Ptotic Breasts, Breast Veining, Breast or Nipple Hair, and Small Breasts. We will add others at your request.


This is where you learn the names of the features of the outside of the breast. You also learn more about variations of those 'standard' features. You get to find out that what you see in the mirror is not that unusual. No one is the same.


What about the things that are inside the breast? When you do a Breast Self-Exam, you feel a lot of things in there, and have no idea what they are. Looking at these images may help you to understand just what is inside those breasts.


There is more to a nipple than you might think. You know what that rubber nipple on the baby bottle is like, but that is nothing like the nipples on your breasts. They are much more involved. For instance: They have five to ten holes, not just one hole.
When you do breast massage, you want to assist the lymphatic fluids in your breasts to flow, and this article may help you to better understand that lymphatic system.. It is quite complex.