Anatomy of the Breast


What are the parts of the breast?
How does the breast produce milk?
What are ducts?
Why should I know the anatomy of the breast?
Where is breast cancer found in the breast?



 
 




What are the parts of the breast?

The breast has 7 parts including the 1) mammary glands, 2) lactiferous ducts, 3) fat, 4) suspensory ligaments, 5) areola (dark area in the center of the breast)/nipple, 6) lymphatic ducts and 7) the overlying skin. (See Fig 1.)

The breasts lie on top of the pectoralis muscles also known as the “pecs”.  There is connective tissue layer that separates the breast from the muscle.  This connective tissue is referred to as deep fascia.  In between the deep fascia and breast is an area called the retromammary space.  The breast may move freely over the pectoralis muscle but is firmly attached to the deep fascia via suspensory ligaments.

How does the breast produce milk?

There are 15-20 mammary glands in each breast.  These glands produce milk after a woman gives birth (lactation).  The milk drains into a lactiferous duct that empties at the nipple.  The bulk of the breast develops at puberty and consists of mostly fat.  When a woman begins to lactate the mammary glands increase in size and the breast increases in size

What are ducts?

There are two types of ducts within the breast.  Both types of ducts are a series hollow tubes that collect fluid.  One type is the lactiferous duct which collects milk from the mammary glands.  The other type of duct is the lymphatic duct which collects liquid referred to as lymph.  The lymph from the breast goes to lymph nodes found in the armpit.  The lymph then returns to the circulatory system via additional lymphatic ducts.

Why should I know the anatomy of the breast?

The normal anatomy is very important because changes in the normal anatomy of your breast can indicate health problems such as breast cancer.  Becoming familiar with yourself will allow you to detect changes early on and will increase your chances of a good outcome should cancer develop.
 
 

Where is breast cancer found in the breast?
 
 




Cancer commonly begins in the ducts.  Most of the ducts are found in the upper quadrant closes to the arm and because of this 50% of breast cancer is first detected there (See Fig 2.)  At the site of cancer lymphatic ducts can be blocked and the thickening of the overlying skin may develop.  This thickening may look similar to an orange peel and can be detected on a mammogram.  If the suspensory ligaments are affected then they may shorten and cause a dimpling in the breast.  In later stages, the cancer can invade the underlying retromammary space, deep fascia and eventually the pectoralis major causing fixation of the breast.  The cancer cells can move to other areas of the body if not detected early.  These “metastatic” cells move to the lymph nodes located near the armpit (See Fig 3.).  They will feel like hard lumps or nodules under the skin.  There is usually not tenderness associated.