Anatomy of the Female Breast

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The female breast is designed to produce milk for the nourishment of a baby. So, it has glands to convert blood into milk, ducts to carry the milk to the nipples and openings on the tip of the nipples to allow the milk to flow out when it is sucked.

The Breast Glands: Each breast is divided into 15 - 20 lobes separated from each other by fat. They surround the nipple in a radial manner, like spokes on a wheel. Each lobe is again divided into lobules that are made up of masses of specialized cells known as alveoli which cluster around tiny tubes known as the ductules. The alveoli synthesizes milk from the blood in the exact proportions that a baby requires for nourishment.

The milk is collected from each alveoli by the ductules which join each other to form a single larger duct called the lactiferous duct. Each lobule is drained by a single lactiferous duct.

Thus, each breast has 15 - 20 lactiferous ducts which drain the milk towards the nipple. Behind each nipple, the duct dilates to form the ampulla where the milk is stored. This milk is released through the lactiferous openings at the tip of the nipple at the time of breastfeeding.

Breast tissue starts growing in an embryo in the uterus around 6 to 7 weeks after conception. At about 16 weeks, cells begin grouping together to form the glands of the breasts. After birth, many children are seen with slightly larger breasts - this is due to the stimulation by the hormones received from the mother.

Anatomy of the Female Breast
Anatomy of the Female Breast

The breasts become flatter within a few months after birth. Further growth is seen around the time of puberty and at the time of pregnancy and breastfeeding. The breast tissue atrophies to some extent after the menopause and at this time the main bulk of the breasts is made up of fat.

Cancerous changes can occur in the cells of the lobules. Lobular Carcinoma in situ (LCIS) is a precancerous condition which can develop into Invasive Lobular Carcinoma (ILC) in time.

The Breast Ducts: There are fifteen to twenty ducts in each breast. Each duct has a number of glandular cells clustering around it - rather like a cluster of grapes around a stem. The lobules are linked by a network of thin tubes which join each other to finally drain into the larger duct draining each lobule. Each duct opens on the tip of the nipple.

Both Ductal Carcinoma in situ (DCIS) and Invasive ductal carcinoma (IDC) originate form the cells lining the ducts.

Breast fat: The breast is surrounded by fat cells known as adipose tissue. The adipose tissue extends from the collar bone and over the muscles of the chest wall, forming the base of the breast tissue. It also surrounds the glandular tissue of the breast all around and extends to the armpit together with a part of the breast tissue known as the tail of Spence.

The main function of the adipose tissue is to increase the blood supply to the breast tissue through the number of blood vessels embedded in the fat. It is the fatty tissue which mainly contributes to the bulk of the breast. When a woman gains weight, there is an increase in the fat in the breast leading to large bulky breasts.

The Areola of the Breast :The areola is a pigmented area about 2.5cm in size placed at the center of the breast surrounding the nipple. It contains numerous sebaceous and sweat glands which keep it well moisturized. It may be of different color gradations depending on the skin color of the woman. The colors may range from a very light pink to darker pink to brown to dark brown to black. The color of the areola deepens during pregnancy, possibly to make it easily visible to the baby. The size also increases and may almost double in some women, forming the secondary areola of the breast. The secondary areola may decrease in size after breastfeeding is over but the main areola does not revert to the pre-pregnancy size after breastfeeding is stopped.

The Nipple of the Breast :The nipple is a pigmented projection in the center of the areola accommodating the 15 to 20 lactiferous ducts and their openings. It contains erectile muscles which causes the nipple to become erect on stimulation. Although the breast is embedded in fat, there is no fat under the areola or nipple.

Humans, both men and women, almost always have two nipples and two breasts. Generally, a mammal has twice as many nipples or teats as the number of offspring it produces at one time. This is why cats and dogs, which produce litters of babies, have a double line of many nipples. The majority of human births are singletons, so humans have two breasts.

The cells of the nipple may undergo cancerous changes to cause an uncommon type of breast cancer known as Paget's disease of the breast.

Sometimes, a man or a woman may be born with extra nipples in a line straight down from the main one on top. These are called Supernumerary nipples and are a remnant of the milk ridge from which all nipples develop. They can be removed by surgery without any problem.

The Ligaments of the Breast : The breast has a number of ligaments which help to suspend it, support it and attach it to the chest muscles. These ligaments become weaker and loose with age or excessive fatty tissue and this causes the breasts to sag. The Cooper's ligament or the SFS (Superficial Suspension fascia System) is the connective tissue that supports the breast on the chest fascia and muscle. It is a film like network of fibers that encases globules of fat and the gland. When this layer loses its support, breast sagging or dropping occurs.

Symmetry of the Breast : No woman has breasts which are exactly similar to each other - in shape or size. Usually, one breast is slightly larger or smaller, higher or lower, or shaped differently than the other. In most cases, this difference is negligible and cannot be identified.

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