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
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5th week of fetal development
- Bilateral ectodermal ridges originating from the axilla to the inguinal region develop into 15-20 buds
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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
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12th week
- Primary buds develop into secondary buds which will eventually form into mammary lobules
2
Q
Describe breast development from weeks 12 to birth.
A
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20th week
- Mammary ridge penetrates the mesoderm and sending radial ingrowths into the breast
- Areola begins to develop
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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
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After birth
- Protrusion of the nipple and development of terminal ducts
3
Q
Describe breast development from birth to 2 years.
A
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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
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From birth-2years
- Further branching and terminal lobule development occurs
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From 2 years-thelarche
- No further development
4
Q
What is the breast development during puberty?
A
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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
5
Q
What are the important factors of complete breast development?
A
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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
6
Q
Describe the Tanner staging of breast development.
A
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Stage I (Preadolescent):
- Papilla elevation above the level of the chest wall.
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Stage II (Breast budding):
- Breast and papilla elevation, along with increased areola diameter.
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Stage III:
- Ongoing enlargement of the breasts and areola.
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Stage IV:
- Elevation of the areola and papilla above the breast mound.
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Stage V (Mature breast):
- Elevation of the papilla with regression of the areola.
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
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Laterally - begins at sternum and extends to mid-axillary line
- axillary tail of SPence extends to theh axilla
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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
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
9
Q
Describe the blood supply of the breast.
A
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Arterial blood supply:
- Internal mammary artery 60%
- Lateral thoracic artery 30%
- Minor contributions from thoracoacromial, intercostals, subcapsular, and thoracodorsal arteries
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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
10
Q
What is the sensory inntervation of the breast?
A
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3rd-6th intercostal nerves, lateral and ant cutaneous branches
- majority of breast
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Supraclavicular nerve, ant cutaneous branches
- skin of the upper portion of the breast
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Intercostobrachial nerve is the lateral cutaneous branch of the 2nd intercostal nerve
- medial aspect of the upper arm
11
Q
Describe the lymphatics of the breast.
A
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Axillary lymph nodes (75%)
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Level I: Lateral to the pec minor
- axillary vein, external mammary, scapular
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Level II: Superficial and deep to the pec minor
- central, Intra pectoral (Rotter’s nodes)
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Level III: Medial to the pec minor
- subclavicular
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Level I: Lateral to the pec minor
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Internal mammary lymph nodes
- medial aspect of the breast