ANATOMY OF THE FEMALE BREAST
The two female breasts lie on the pectoralis major and seratus anterior muscles at the level of the 2nd to 6th ribs on which they are attached by a layer of fascia and ligaments called cooper’s ligaments. They extend from the from the clavicles superiorly and the superior abdominal wall inferiorly. The axillary tail of the breast passes between the pectoral muscles and the latisimus muscle of the back to reach the lower part of the axilla. The breast is made up by modified sweat glands called mammillary glands, ducts, supporting fibrous tissue and fat. Small glands, called lobules produce milk which is carried by ducts to larger glands from which about 20 larger ducts transmit the secretions to the nipples. The glandular part of the breast is concerned with the secretion of milk while the fatty and muscular tissues as well as the fascia have a supporting role.
The two female breasts lie on the pectoralis major and seratus anterior muscles at the level of the 2nd to 6th ribs on which they are attached by a layer of fascia and ligaments called cooper’s ligaments. They extend from the from the clavicles superiorly and the superior abdominal wall inferiorly. The axillary tail of the breast passes between the pectoral muscles and the latisimus muscle of the back to reach the lower part of the axilla. The breast is made up by modified sweat glands called mammillary glands, ducts, supporting fibrous tissue and fat. Small glands, called lobules produce milk which is carried by ducts to larger glands from which about 20 larger ducts transmit the secretions to the nipples. The glandular part of the breast is concerned with the secretion of milk while the fatty and muscular tissues as well as the fascia have a supporting role.
The size of the breast depends on the amount of fat present around the glands but the proportion between glands, ducts and fat changes with age. The developing breast consists mostly of ducts. The mammary glands are the main component in the fully developed breast of a young woman and this tissue increases dramatically in pregnant women and during lactation, whereas after menopause the glandular tissue decreases rapidly. On the other hand the fat content of the breast increases with age and in elderly women almost all the breast tissue is replaced by fat.
The breasts are supplied by by two main arteries, the internal mammary artery which descends on the undersurface of the sternum and gives branches to supply the breast and the lateral thoracic artery which descends the from the axilla. Corresponding veins drain the blood back to the body.
Lymphatic vessels run alongside the arteries and collect the fluid that ‘leaks’ from the blood vessels to return it back to the main circulation after it has been filtered from pathogens that can cause infections and abnormal cells. For this reason cancer cells from a breast tumour can be through the lymph vessels into the blood supply and other areas of the body. Thus deep knowledge of the lymph drainage of the breast can be helpful to predict secondary tumour sites. The main lymphatic drainage of the breast goes through the axilla which consists from about 10-30 lymph nodes situated underneath the axillary vein. There are three groups of axillary lymph nodes lower (level I), Central (level II) and superior (level III) lymph nodes and lymph flows from the lower to the most superiorly located lymph nodes. Some of the lymphatic fluid drains into the internal mammary nodes located at the midline of the chest wall and a small amount drains into nodes of the abdomen and along the side of the back
The breasts are supplied by by two main arteries, the internal mammary artery which descends on the undersurface of the sternum and gives branches to supply the breast and the lateral thoracic artery which descends the from the axilla. Corresponding veins drain the blood back to the body.
Lymphatic vessels run alongside the arteries and collect the fluid that ‘leaks’ from the blood vessels to return it back to the main circulation after it has been filtered from pathogens that can cause infections and abnormal cells. For this reason cancer cells from a breast tumour can be through the lymph vessels into the blood supply and other areas of the body. Thus deep knowledge of the lymph drainage of the breast can be helpful to predict secondary tumour sites. The main lymphatic drainage of the breast goes through the axilla which consists from about 10-30 lymph nodes situated underneath the axillary vein. There are three groups of axillary lymph nodes lower (level I), Central (level II) and superior (level III) lymph nodes and lymph flows from the lower to the most superiorly located lymph nodes. Some of the lymphatic fluid drains into the internal mammary nodes located at the midline of the chest wall and a small amount drains into nodes of the abdomen and along the side of the back
Sensation to the breast is carried by intercostal nerves 4-6 which travel between the ribs originating from corresponding thoracic segments of the spinal cord. Branches of those nerves pierce the fascia covering the pectoralis major muscle and travel through the breast tissues to reach the subcutaneous tissue and skin covering the breast. Furthermore those branches carry sympathetic fibres to supply the blood vessels, smooth muscles and skin around the nipple of the breast.