Breast Physiology and Benign Diseases 1 Flashcards

To describe basic rmbryology, anatomy, and physiology of the breast.

1
Q

Describe breast development up to week 12.

A
  • —5th week of fetal development
    • —Bilateral ectodermal ridges originating from the axilla to the inguinal region develop into 15-20 buds
  • —7th week
    • —Buds undergo apoptosis except for a single pair at the 4th-5th intercostal space called the primary mammary buds
    • —Breast development begins as these buds penetrate into underlying mesoderm
  • —12th week
    • —Primary buds develop into secondary buds which will eventually form into mammary lobules
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2
Q

Describe breast development from weeks 12 to birth.

A
  • —20th week
    • —Mammary ridge penetrates the mesoderm and sending radial ingrowths into the breast
    • —Areola begins to develop
  • —2nd and 3rd trimester
    • —Sweat, sebaceous, and apocrine glands develop into Montgomery glands
    • —Lumina develop within the mammary buds developing into the lactiferous ducts, a mammary pit, and eventually a nipple in infancy
  • —After birth
    • —Protrusion of the nipple and development of terminal ducts
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3
Q

Describe breast development from birth to 2 years.

A
  • —At birth
    • —15-20 radial mammary lobes
    • colostrum within the lactiferous ducts due to placental hormones results in normal milky discharge post partum days 4-7
  • —From birth-2years
    • —Further branching and terminal lobule development occurs
  • —From 2 years-thelarche
    • —No further development
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4
Q

What is the breast development during puberty?

A
  • —Puberty begins between ages 8-12 years
    • —Hypothalamus releases increased GnRH
    • —Increased secretion of FSH and LH from the pituitary
    • —Leads to maturation of the ovarian follicles resulting in production of estrogen and progestins
    • —Mammary ductal epithelium and stroma proliferate under ovarian estrogen
    • —Terminal duct lobules, collecting ducts and breast buds proliferate
    • —Vascular and connective tissue proliferate increasing breast size—
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5
Q

What are the important factors of complete breast development?

A
  • —Complete breast development requires:
    • insulin, cortisol, thyroxine, prolactin and GH
    • adequate body fat: 16-24% to maintain normal cycles
    • adequate sleep: gonadotropins released during sleep cycles required for nl menstrual cycles
    • exposure to sunlight: optimizes pituitary secretion of gonadotropins
  • —Breast development stops 2 years after onset of menarche
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6
Q

Describe the Tanner staging of breast development.

A
  • —Stage I (Preadolescent):
    • —Papilla elevation above the level of the chest wall.
  • —Stage II (Breast budding):
    • —Breast and papilla elevation, along with increased areola diameter.
  • —Stage III:
    • —Ongoing enlargement of the breasts and areola.
  • —Stage IV:
    • —Elevation of the areola and papilla above the breast mound.
  • —Stage V (Mature breast):
    • —Elevation of the papilla with regression of the areola.
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7
Q

Describe surface breast anatomy.

A
  • Spans from 2nd intercostal space to 6th or 7th intracostal fold at the level of the inframammary fold
  • Laterally - begins at sternum and extends to mid-axillary line
    • axillary tail of SPence extends to theh axilla
  • Breast divided into four quadrants:
    • upper outer
    • upper inner
    • lower outer
    • lower inner
  • Upper quadrant is most fibroglandular and most frequent area for tumors of the breast
  • Nipple is at the 4th intercostal space with multiple sensory nerve endings
    • includes Ruffini corpuscles and Krause end bulbs
    • areola has sebaceous and apocrine sweat glands as well as Montogmery glands along periphery
    • radial smooth muscle extends toward the dermis of the nipple and lead to the nipple erection with stimulation
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8
Q

Describe cross sectional breast anatomy.

A
  • Thinnk skin with hair follicles and sebaceous and eccrine glands
  • Underneath skin is subcutaneous fat
    • superficial fascia within is fibroglandular breast tissue
  • Deep fascia below fibroglandular layer and is anterior to pectoralis major
    • Cooper’s ligaments attach to superficial and deep fascias to provide support
  • Fibroglandular tissue (breast parenchyma) is composed of 15-20 lobes, each with 15-20 lobules and consistin gof 10-100 alveoli
    • each lob with minor interlobular ducts that drain into major lactiferous ducts
    • about 10 major collecting milk ducts open into the nipple
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9
Q

Describe the blood supply of the breast.

A
  • —Arterial blood supply:
    • —Internal mammary artery 60%
    • —Lateral thoracic artery 30%
    • —Minor contributions from thoracoacromial, intercostals, subcapsular, and thoracodorsal arteries
  • —Venous drainage:
    • —Courses towards the axilla along the same path as the arteries
    • —Circulus venosus: an anastamotic circle of veins underlying the nipple-areolar complex
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10
Q

What is the sensory inntervation of the breast?

A
  • —3rd-6th intercostal nerves, lateral and ant cutaneous branches
    • —majority of breast
  • —Supraclavicular nerve, ant cutaneous branches
    • —skin of the upper portion of the breast
  • —Intercostobrachial nerve is the lateral cutaneous branch of the 2nd intercostal nerve
    • —medial aspect of the upper arm
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11
Q

Describe the lymphatics of the breast.

A
  • —Axillary lymph nodes (75%)
    • —Level I: Lateral to the pec minor
      • axillary vein, external mammary, scapular
    • —Level II: Superficial and deep to the pec minor
      • central, Intra pectoral (Rotter’s nodes)
    • —Level III: Medial to the pec minor
      • —subclavicular
  • —Internal mammary lymph nodes
    • medial aspect of the breast—
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