Embryology and Anatomy of breast ‐B.Shivraj Gen Surg 1st unit The mammary gland • Modified apocrine sweat gland. • Present in both males and females. • Female ‐> serves for lactation; secondary sexual character. • About 4% women have amazia. Embryology • Develops from the integument. • Arises from the ventral surface of the embryo.(milk line‐> thickened line of ectoderm). • Ducts and acini from ectoderm • Supporting tissue from mesenchyme. Milk line *Milk line / mammary ridge‐> Develops from base of fore limb i.e. Axilla to hind limb i.e groin. *Except @ the level of nipple, rest of It gets atrophied. *Polythelia‐> m/c site 7‐10cm Below and medial to the nipple. • Dev @ 6th week of IU life. ‐>mammary ridge • @nipple‐>ectoderm grows inward 15‐20 solid rods (rudimentary gland)‐>bulbous dilation at ends‐>alveoli • @5th month IU life‐>cords develop • @7/8th month‐>hollowing of ducts; diff as milk ducts; depression at site of nipple. • @9th month‐> alveoli become canalised • @birth‐>mesenchyme proliferation‐> nipple everts; areola becomes pigmented. • @puberty‐> 15‐20 lact ducts have 15‐20 lobules each. • Witch’s milk‐> creamy white fluid cos of circulating maternal estrogens • Colostrum‐> intial milk secreted. Rich in antibodies cos of lymphocytes and plasma cells in the duct lining. • Later stage replaced by milk high in lipid content. Location • Situated in the anterior chest wall : 2‐6rib; sternum to mid‐axillary line; surrounded by the superficial fascia; resting on the deep fascia. overlying the pectoral fascia Breast: Fatty Tissue Nipple and areola complex • Nipple‐> 4th ICS. – Smooth muscles; circular and longitudinal – Erection‐>serves milk • Areola‐>sebaceous/areolar glands – Pigmented – Has hypertrophied sweat glands‐> glands of Montomery‐>serves for protective lubrication during lactation. Lobes and Lobules Anatomy • Ducts, acini‐>lobules‐>lobes‐> latiferous ducts‐>lactiferous sinus‐>nipple. • Suspensory ligaments of Astley Cooper‐skin and petoralis muscle. • Tail of spence‐ foramen of langer (d/d‐ lymph node); @ 3rd rib level ; Ln Blood supply • Arterial – – 1st part of subclavian‐>internal mammary art(medial mammary brs) along with 2,3,4th IC perf brs. abt 50% BS. – 2nd part of axillary‐> external mammary art(lateral thoracic brs)‐> lateral aspect – Pectoral branches of acromiothoracic artery‐> post. aspect • Superior thoracic br • Lateral perf br of IC art. • Br. of subscapular art. Arterial Supply to the Breast Subclavian a. Axillary a. Internal mammary External (thoracic) a. mammary (thoracic) a. Veins draining the Breast Subclavian vein External mammary vein Venous drainage • Follows the arteries. • Internal mammary v.‐> s/c v. • Lat thoracic ‐> ax. V • Lat. Perf. Br. Into IC v‐> vertebral v ‐> vertebral plexus‐> bone mets. “BATSON’S PLEXUS” Nerve supply • anterior & lateral br of 4‐6th IC n. • Nipple‐> T4 ; extensive plexus • Areola‐> fewer nerve endings. Lymph Nodes of the Breast Subclavian nodes Axillary nodes Parasternal Lateral nodes pectoral nodes Lymph drainage Lymphatic drainage • Is of great surgical importance • Arises in interlobular conn tissue and in walls of lactiferous ducts • Majoirty of breast drains into axillary LN. • 5groups: – Pectoral(anterior) – 75% – Subscapular(posterior) – Humeral(lateral) – Sublavicular(apical)‐ultimately – Central • Parasternal nodes • Rotter’s nodes • In relation to pec minor: – Level I – Level II – Level III ‐ Also to supraclavicular nodes. Routes of Metastasis • Across the sternum in lymphatics to opposite side via cross‐mammary pathways – Then to contralateral breast • From subdiaphragmatic lymphatics to nodes in abdomen – Then to liver, ovaries, peritoneum Major Routes of Metastasis Channels to Contralateral Breast Axillary Lymph Channels Subdiaphragmatic Lymph Channels Anomalies • Amazia – B/L ; U/L • Polymazia‐ loc. • Micro/macro • Polythelia / hyperthelia‐ loc. • Gynecomastia • Poland’s synd. • Turner’s synd. • Fleischer’s synd. • Varginal hypertrophy • Symmastia Applied surgical anatomy Clavipectoral fascia • Or costocoracoid / coracoclavicular fascia. • Under pec major muscle. • Upwards‐> encloses subclavius and attaches to clavicle. Post layer fuses with the deep cervical fascia and axillary vessel sheath. • Laterally‐> thickened and attached to coracoid process. • Bet 1st rib and coracoid process‐>costocoracoid lig. • Downwards‐>encloses pec. minor & continuous with axillary fascia. • Pierced by‐> cephalic v ; thoraco acromial art & v ; lateral pectoral nerve. Axilla • Pyramid; apex towards head ; base broader & towards arm. • Apex‐> outer surface of 1st rib; post aspect of clavicle; upper surface of scapula • Medially‐> 1,2,3,4th ribs with intercoastal muscles with serratus ant. • Laterally‐> humerus, biceps brachii, corachobrachialis. • Base ‐> axillary fascia(bet pec major & lat dorsi); med‐ broad, lat‐narrow • Ant‐>pec major, pec minor • Post‐>subscapularis, teres major, lat dorsi • Contents‐>Ax vessels, brachial plexus, Lymphatic system, intercoastal nerves, fat & loose areolar tissue. Cervico‐axillary canal Axillary fascia Dissection • Abduct arm at 90 degree. • Reflect lower skin flap until post. ax. fold is visible • LN and superficila v dissected. • 2 muscles: lat. S head of biceps; med‐ coracobrachialis • Medial borders defined • Axillary vessels skeletonised. • Long thoracic n and intercostobrachial n. THANK YOU.