Embryology and of

‐B.Shivraj Gen Surg 1st unit The

• Modified apocrine sweat gland. • Present in both males and females. • Female ‐> serves for ; 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 ). • Ducts and acini from ectoderm • Supporting tissue from . Milk line

*Milk line / ‐> Develops from base of fore limb i.e. to hind limb i.e groin.

*Except @ the level of , 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; 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 ; 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‐ and petoralis muscle. • ‐ 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