The Breast

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Breast (Mammary Gland)

  • 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 
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• Anterior chest wall 

• Between 2nd and 6th ribs 

• Lateral extension to mid-axillary line 

• Lie over Pectoralis Major muscle

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External structure of the breast

  • Nipple 
  • Areola 
  • Montgomery’s glands 
  • Skin  
  • Axillary tail 
  • Intra-mammary crease 
  • Margin of Pectoral Major muscle 
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Situation and position

  • Nipple 
  •  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 
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Excretory (lactiferous) ducts

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

• Axillary Tail of Spense 

• Areola – central and pigmented 

• Montgomery’s Tubercles 

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

• These lead to Lactiferous Tubules

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Tail of Spence

“Tail of Spence”  axillary tail 

• prolongation of upper, outer quadrant in axillary direction 

• Passes under axillary fascia 

• May be mistaken for axillary lymph nodes 

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• Milk glands (lobules) 

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

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Blood Supply

• Internal and external mammary arteries 

• Upper intercostal arteries 

• Internal mammary veins 

• Axillary veins 

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Lymph Drainage

• Axillary glands 

• Anterior mediastinum 

• Portal fissure of the liver 

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Nerve Supply

• Poor nerve supply 

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

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Fetal breast development

• 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 

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Newborn breasts

  • Nipples poorly formed at birth 
  • Depressed in newborn infants 
  • Nipples 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)
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Breasts in childhood

• Inactive 

• Under developed 

• Growth is minimal 

• Growth due to proliferation of connective tissue of the areola 

• Dormant until puberty

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Breasts during 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

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• Generate fat deposition 

• Encourage growth of ducts 

• Initiate growth of milk producing apparatus 

• Responsible for external appearance of mature female breast 


• Generates growth of tubules and alveoli 

• Causes acini cells to proliferate 

• Generates secretory action of acini cells 

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Hormones continued


• Contributes to growth of tubules and alveoli 

• More important to milk production after pregnancy


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

• Inhibited by stress, pain, anxiety 

• Triggered by sound, smell, sight of infant 

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Physiology of Lactation

  • 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 ******
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Initiation of lactation

Latch On and sucking 

Oxytocin Release 

Releases Milk 

Infant Empties Breast 

Production Increases 

Milk Production Occurs 

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