ANATOMY OF BREAST

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ANATOMY OF BREAST : 

ANATOMY OF BREAST Dr.B.Balagobi

POSITION OF BREAST : 

POSITION OF BREAST The base of the breast extends from the second to the sixth rib and from the lateral margin of the sternum to the midaxillary line. The greater part of the gland lies in the superficial fascia. A small part-axillary tail extends upward and laterally, pierces the deep fascia at the lower border of the pectoralis major muscle up to the apex of the axilla. The breast lies upon the deep pectoral fascia, which in turn overlies pectoralis major and serratus anterior, and inferiorly, external oblique and its aponeurosis as the latter forms the anterior wall of the sheath of rectus abdominis.

Breast shape : 

Breast shape Breast shape and size depend upon genetic, racial and dietary factors, and the age, parity and menopausal status of the individual. Breasts may be hemispherical, conical, variably pendulous, piriform or thin and flattened. The main bulk of the breast tissue is usually localized to its upper outer quadrant. This quadrant is more often implicated in breast cancer and in most benign lesions of breast tissue.

Nipple & Areola : 

Nipple & Areola The nipple level in the thorax varies widely, but is at the fourth intercostal space in most young women. Nipple is Usually everted. The areola is a disc of skin, which circles the base of the nipple, varying in colour from pink to dark brown depending on parity and race. Melanocytes are quite numerous in the skin of the nipple and areola, giving them a darker colour than the remainder of the breast. Further darkening of the nipple and areola occurs during the second month of pregnancy, a change that persists to a variable degree.

Fascial relationships of the breast : 

Fascial relationships of the breast The fascial relationships of the breast are of practical importance. As an ectodermal derivative, the gland lies in a pocket of superficial fascia. Superficial fascia: Superficial layer Deep layer The superficial layer lies immediately beneath the dermis and enables skinflaps to be dissected from the glandular mass of the breast quickly, neatly, and in a relatively avascular plane.

Fascial relationships of the breast : 

Fascial relationships of the breast The deep layer of the superficial fascia is thicker than the subcu- taneous component and covers the deep aspect of the breastplate. Beneath this sheath is a layer of filmy areolar tissue that allows the breast to move freely on the underlying fascial covering of the pectoralis major and the serratus anterior.(Pectoralis fascia) This areolar layer forms the retromammary space/ Submammary space. Deep infiltration of a cancer through this space into the underlying pectoralis fascia produces the physical sign of deep tethering of a malignant breast mass. Precise establishment of the plane of the retromammary space enables rapid and relatively blood- less dissection of the deep aspect of the breast in simple mastectomy.

Fascial relationships of the breast : 

Fascial relationships of the breast Fibrous processes of this layer of fascia extend to the skin and to the nipple and are more developed over the upper part of the breast, where they form the suspensory ligament of Cooper. Contraction of this tissue by malignant infiltration results in the characteristic skin dimpling over a carcinoma of

Structure of breast : 

Structure of breast Each breast consists of 15 to 20 lobes, which radiate out from the nipple which embedded in fat. The main duct from each lobe opens separately on the summit of the nipple and possesses a dilated ampulla just before its termination. The lobes of the gland are separated by fibrous septa that serve as suspensory ligaments.

Structure of breast : 

Structure of breast lobes,consisting of branching ducts and terminal secretory lobules in a connective tissue stroma. The connective tissue stroma which surrounds the lobules(Intralobar) is dense and fibrocollagenous, whereas intralobular connective tissue has a loose texture, which allows the rapid expansion of secretory tissue during pregnancy . fibrous tissue surrounds the glandular components and extends to the skin and nipple, assisting in the mechanical coherence of the gland. The interlobar stroma contains variable amounts of adipose tissue, which contributes largely to the increase in breast size at puberty . The 15–20 lactiferous ducts open on to the nipple.

Stages of development : 

Stages of development From birth until puberty, the breast consists of lactiferous ducts, with no alveoli. At puberty, the ducts start to proliferate, and their terminations form solid masses of cells—the future breast lobules. During pregnancy, secreting alveoli appear. During the early weeks, ductal sprouting and lobular proliferation occur, with increased nipple and areolar pigmentation. The alveoli now display a lumen surrounded by the secretory cells. In the last days of pregnancy, the breasts secrete colostrum, a yellow, sticky, serous fluid, which is then replaced by true secre- tion of milk. When lactation ceases, the glandular tissue returns to its resting state.

Stages of development : 

Stages of development After the menopause, the glandular tissue of the breast atrophies, the connective tissue becomes less cellular, and the amount of collagen decreases. In some women, marked fatty infiltration of the breast occurs at this stage; in others, the breasts shrink considerably. Neonates:Occasionally, gynaecomastia may occur in the neonatal breast, with discharge of a colostrum-like material (‘witch’s milk’).

Glands of Montgomery : 

Glands of Montgomery The nipple contains large sebaceous glands that are often visible to the naked eye—the glands of Montgomery.

Blood supply : 

Blood supply The blood supply of the breast is a rich anastomotic network derived from the axillary artery internal thoracic (internal mammary) intercostal arteries . The largest vessels arise from the internal thoracic artery, the perforating branches of which pierce the chest wall adjacent to the sternal edge in the first to fourth intercostal spaces. The vessel in the second space is usually the largest of these. second to fourth anterior intercostal arteries supply perforating branches more laterally. The axillary artery supplies blood from several branches, namely the superior thoracic, the pectoral branches of the thoraco-acromial artery, the lateral thoracic artery.

Lymphatic drainage : 

Lymphatic drainage This is of considerable importance in the spread of breast tumours. The lymph drainage of the breast, as with any other organ, follows the pathway of its blood supply and therefore travels: along tributaries of the axillary vessels to axillary lymph nodes; along the tributaries of the internal thoracic vessels to the internal mammary chain Along the intercostal vessels.

Lymphatic drainage : 

Lymphatic drainage there is a tendency for the lateral part of the breast to drain towards the axilla and the medial part to the internal mammary chain

The axillary lymph nodes : 

The axillary lymph nodes The axillary lymph nodes (some 20–30 in number) drain lymphatics of the breast pectoral region Upper abdominal wall upper limb arranged in five groups : anterior :lying deep to pectoralis major along the lower border of pectoralis minor; posterior—along the subscapular vessels; lateral—along the axillary vein; central—in the axillary fat; apical (through which all the other axillary nodes drain)at the apex of the axilla above pectoralis minor and along the medial side of the axillary vein.

The axillary lymph nodes : 

The axillary lymph nodes From the apical nodes emerges the subclavian lymph trunk. On the right, this either drains directly into the subclavian vein or else joins the right jugular trunk; on the left it usually drains directly into the thoracic duct. Clinicians and pathologists often define metastatic axillary node spread simply into three levels: level I—nodes inferior to pectoralis minor; level II—nodes behind pectoralis minor; level III—nodes above pectoralis minor.

Lymphatic drainage : 

Lymphatic drainage Lymphatic spread of a growth of the breast may occur further afield when these normal pathways have become interrupted by malignant deposits, surgery or radiotherapy. Secondaries may then be found in the lymphatics of the opposite breast or in the opposite axillary lymph nodes the groin lymph nodes (via lymph vessels in the trunk wall) the cervical nodes (as a result of retrograde extension from the blocked thoracic duct or jugular trunk in peritoneal lymphatics spreading there in a retrograde manner from the lower internal mammary nodes

Development : 

Development The breasts develop as an invagination of chest wall ectoderm which forms a series of branching ducts. Shortly before birth this site of invagination everts to form the nipple. At puberty, alveoli sprout from the ducts and considerable fatty infiltration of the breast tissue takes place. With pregnancy there is tremendous development of the alveoli which, in lactation, secrete the fatty droplets of milk. At the menopause the gland tissue atrophies.

Developmental abnormalities of Breast : 

Developmental abnormalities of Breast The nipple may fail to evert . Supernumerary nipples or even breasts may occur along a vertical ‘milk line’ the other hand, the breast on one or both sides may be small or even absent (amazia).

Accessory breast : 

Accessory breast

Skin tethering : 

Skin tethering

Nipple retraction : 

Nipple retraction

Axillary lymh node enlargement : 

Axillary lymh node enlargement

Peau d’orange : 

Peau d’orange

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