BREAST AND ITS DEVELOPMENT

Learning objectives

•  To know about the anatomy of breast

•  To know about the relation of breast within pectoral region

•  To know about the blood supply of breast

•  To know about lymphatic drainage of breast

•  To know the relation of breast disease with axilla

Lecture outlines

•  Introduction

•  Anatomical relations of breast

•  Structure of breast

•  Blood supply of breast

•  Lymphatic drainage of breast

•  Clinical correlates

•  Development of breast and related anomalies

Introduction

•  Accessory gland of skin

•  Modified sweat gland

•  Well developed in post-pubertal females

•  Rudimentary in males and pre-pubertal females

•  Secretes milk, thus provide nutrition to new born

Anatomical relations

§  Situation

•  Greater part of gland lies in superficial fascia of pectoral region

•  A small extension, axillary tail(of Spence) directed upwards and laterally to pierce the deep fascia around lower border of pectoralis major and lie in axilla

§  Extent of the base of breast:

•  Vertically----from 2nd to 6th rib

•  Horizontally--- from lateral border of sternum to mid axillary line

Deep relations of breast

  1. Retromammary space (loose areolar tissue)
  2. Pectoralis fascia covering pectoralis major
  3. Parts of pectoralis minor, serratus anterior and external oblique muscle

Structure of breast
Divided into skin,parenchyma, stroma

§  SKIN:

•  Covers the breast

•  Has nipple and areola

•  Skin of areola and nipple is devoid of hairs anD sub cutaneous fat

•  Nipple

•  conical projection below the center at fourth intercostal space

•  Pierced by lactiferous ducts

•  Has few modified sweat and sebaceous glands and longitudinal and circular smooth muscle

•  Rich in nerve supply

•  AREOLA:

•  Circular area of pigmented skin around the base of nipple

•  Rich in modified sebaceous gland, more at outer border

•  Tubercles of Montogomery– enlarged sebaceous gland during pregnancy and lactation

•  Also contain sweat gland and accessory mammary gland

•  Parenchyma

•  Glandular tissue

•  Consists of 15 to 20 lobes

•  Each lobe (cluster of alveoli) drained by lactiferous duct that open separately on summit of nipple

•  Lactiferous sinus or ampulla is a dilatation near opening on nipple

•  Stroma:

•  Forms supporting frame work

•  Partly fibrous, partly fatty

•  Suspensory ligament of cooper---- septa of fibrous stroma extending from skin to deep fascia

•  These septa divide parenchyma into a compartment, each compartment contain a lobe of gland

•  Fatty stroma forms main bulk of breast

A------lactiferous ducts

B------lobule(alveoli)

C------lactiferous sinus

D------opening

E ------subcutaneous fat

F--- pect. Major

G----- ribs and intercostal muscle

For enlargement

A ---- epithelium

B-----basement membrane

C------lumen of duct

Blood supply of breast

§  Arterial supply

•  Mainly from anterior surface ,posterior surface is relatively avascular

·  Sub clavian artery through its Internal thoracic branch ( perforating branches)

·  Axillary artery through itsLateral thoracic, sperior thoracic and acromiothoracic Branches

·  Posterior intercostal arteries through their lateral branches

·  Venous supply

·  Veins first converge towards the base of nipple forms anastomosing circle

·  Divides into superficial and deep sets

·  Superficial drains into internal thoracic vein and superficial veins of neck

·  Deep veins into internal thoracic, axillary and posterior intercostal veins

·  Nervous and hormonal control

·  Breast is supplied by anterior and lateral branches of 4th to 6th intercostal space

·  Sensory fibers supply skin

·  Autonomic fibers supply smooth muscle of nipple and to blood vessels

·  Milk secretion is controlled by hormones

·  Prolactin that comes from anterior lobe of pituitary gland produces milk

·  Oxytocin that comes from posterior lobe of pituitary controls ejection of milk from breast

·  Lymphatic drainage of breast

·  Lymph nodes

·  Lateral quadrants of breast drains into anterior group of axillary lymph node

·  Medial quadrants by internal thoracic or parasternal nodes

·  May follow posrerior intercostal arteries to posterior intercostal nodes

·  May also go to supraclavicular, deltopectoral nodes and comminucate with vessels of opposite breast

·  Lymphatics of breast

·  Superficial drain the skin over the breast exept for nippleand areola to surrounding nodes

·  Deep lymphatics drain the parenchyma and nipple and areola

·  Clinical correlates

·  Mammography:

·  Radiographic examination of breast

·  Used extensively for screening benign and malignant tumors and cysts

·  Can detect very small lesions long before it can be palpated

·  Importance of fibrous septa in breast abscess

·  Results from acute infection of breast during lactation

·  Due to the septation into compartments, remain localized to one lobe

·  Should be drained by radial incision to avoid cutting radially arranged ducts

·  Carcinoma of breast

·  If the cancer involves suspensory ligaments then the contraction of ligament in fixed breast results in retraction or puckering of skin

·  infiltration and fibrosis of lactiferous ducts cause retraction of nipple

·  Mostly occur in outer upper quadrant resulting in metastasis to anterior group of axillary lymph nodes

·  Through communication of superficial lymphatics, spread to opposite breast, liver, pelvis

·  Through communication by veins, spread to vertebrae and brain

·  Peau d’ orange appearance like peel of an orange– due to edema as a result of lymphatic blockage by cancers cell

·  DEVELOPMENT OF BREAST

·  Derivative of ectoderm

·  Derive from mammary line or ridge

·  Extends from the base of fore limb to base of hind limb

·  The portion of ridge in thorax persists , penetrates the mesenchyme and forms 16 – 24 sprouts

·  By the end of prenatal life ,epithelial sprouts are canalized to form lactiferous ducts opening into a pit

·  Buds form small ducts and alveoli of gland

·  After birth nipple is formed due to proliferation of mesenchyme of the pit

·  Anomalies of breast development

·  Polythelia

·  Accessory nipples

·  Persisitence of mammary ridge

·  Usually in axillary region

·  Polymastia

·  remnant of mammary line develops into a complete breast

·  Inverted nipple

·  Original pit that failed to evert