The Breast

• Mamma  Latin term for breast 
• Mammae exist in both sexes 
• In males they are rudimentary throughout life In females  underdeveloped until puberty 
• Appearance and shape of female breasts vary between individuals 

• Anterior chest wall 

• Between 2nd and 6th ribs 

• Lateral extension to mid-axillary line 

• Lie over Pectoralis Major muscle

• ****** 
• Areola 
• Montgomery’s glands 
• Skin  
• Axillary tail 
• Intra-mammary crease 
• Margin of Pectoral Major muscle 

• ****** 
•  Areola 
• Montgomery’s glands (glands which surround the ****** - keep breast lubricated and protected)
• Skin 
• Axillary tail (breast tissue up into the underarm)
• Intra-mammary crease (underneath of breast)
• Margin of Pectoral Major muscle 

• Excretory (lactiferous) ducts converge (tend towards) toward areola 
• Form ampullae (collection sites of lactiferous sinuses)
• Ducts become contracted at base of ****** 

• Hemispherical 

• Axillary Tail of Spense 

• Areola – central and pigmented 

• Montgomery’s Tubercles 

• ****** – erectile – 15 -20 openings  Ampulla (reservoir) 

• These lead to Lactiferous Tubules

“Tail of Spence”  axillary tail 

• prolongation of upper, outer quadrant in axillary direction 

• Passes under axillary fascia 

• May be mistaken for axillary lymph nodes 

• Milk glands (lobules) 

• Ducts  transport milk from lobules to ******

• Internal and external mammary arteries 

• Upper intercostal arteries 

• Internal mammary veins 

• Axillary veins 

• Axillary glands 

• Anterior mediastinum 

• Portal fissure of the liver 

• Poor nerve supply 

• Skin supplied by cutaneous branches of the 4th, 5th and 6th thoracic nerves

• Growth begins at 6 weeks 

• Solid in-growths of the epidermis 

• Growth occurs along the mammary ridges 

• Primary bud develops secondary buds 

• These develop into lactiferous ducts and their branches 

• In late fetal life the epidermal origin of the breast becomes a mammary pit 

• ******* poorly formed at birth 
• Depressed in newborn infants 
• ******* rise soon after birth 
• This is due to proliferation of surrounding connective tissue of the areola 
• Mammary glands of the newborn are identical and often enlarged 
• Witch’s milk (neonatal milk secretion)

• Inactive 

• Under developed 

• Growth is minimal 

• Growth due to proliferation of connective tissue of the areola 

• Dormant until puberty

• Active 
• Growth of duct system 
• Fat and connective tissue proliferate (increase rapidly)
• Hormonal influence 
• Oestrogen, progesterone and prolactin 
• Menstrual cycle generates changes in breast in preparation for pregnancy and lactation

Oestrogen 

• Generate fat deposition 

• Encourage growth of ducts 

• Initiate growth of milk producing apparatus 

• Responsible for external appearance of mature female breast 

Progesterone 

• Generates growth of tubules and alveoli 

• Causes acini cells to proliferate 

• Generates secretory action of acini cells 

Prolactin 

• Contributes to growth of tubules and alveoli 

• More important to milk production after pregnancy

Oxytocin 

• Moves milk from lobules to sinuses, so baby can eat 

• Inhibited by stress, pain, anxiety 

• Triggered by sound, smell, sight of infant 

• After delivery of the placenta, oestrogen levels fall 
• Anterior pituitary releases prolactin
•  Milk secretion is stimulated Milk produced by the acini cells  
• Droplets pushed through cell membrane into alveoli 
• Baby suckles at breast
•  Posterior pituitary releases oxytocin 
• Oxytocin contracts myoepithelial cells
• MIlk propelled into duct
• Ampulla acts as reservoir
• Baby sucks milk from ampulla into lactiferous tubules and onto surface of the ******

Latch On and sucking 

Oxytocin Release 

Releases Milk 

Infant Empties Breast 

Production Increases 

Milk Production Occurs