Breast Anatomy and Development Flashcards
Development of mammary glands begins in what week of embryonic life?
4th week
Milklines extend from what regions?
Axilla to inguinal
With each menstrual cycle the breast undergoes what changes?
proliferative and involutional changes
Ages 6-8 the glandular tissue of one breast may start to develop.
Tender discoid lump beneath areola.
Resolved by age 9 or puberty.
Unilateral early ripening (premature thelarche)
Causes of precocious puberty?
Estrogen secreting ovarian or adrenal tummor.
Changes within hypothalamus or pituitary glands.
Presence of accessory (supernumerary) nipples?
Polythelia
What is the most common breast anomaly that can affect male or female? Can develop anywhere along the milkiness.
Polythelia
Accessory breast, more common without nipple/areola and often forms in the axillary region is called what?
Polymastia
Term for absence of nipple?
Athelia
Term for absence of breast and nipple?
Amastia
Absence of breast tissue secondary to excessive radiation exposure or from surgical excision?
Amazia
Breasts are modified ____?
apocrine sweat glands
Breasts overlie which ribs?
2nd to 6th
The nipple is a what?
Fibromuscular papilla
Small ___ ducts exit the surface of the nipple and drain the ____ ducts.
excretory, lactiferous
What is the areola?
pigmented skin that encircles the nipple.
The areola contains numerous sebaceous glands (Montgomery’s glands) that do what?
Release fatty substance that protects the nipple during lactation.
Functional glandular tissue is composed of how many lobes?
15 to 20
What is the TDLU structure?
Acini > small branching ducts (lobule) > main lactiferous duct (segment duct) > lactiferous sinus (ampulla) > nipple
What is the functional unit of the breast?
Terminal duct lobular unit (TDLU)
Supportive elements of the breast and consist of fat and fibrous connective tissues are what?
stromal tissue
This extensive capillary network allows the exchange of hormones into and secretions out of the lobule.
Loose intralobular stroma
Breast is also supported by dense connective tissue sexton called what?
Coopers ligaments
What is the main arterial supply of the breast?
Branches from lateral thoracic artery (external mammary artery) and branches of internal mammary (thoracic) artery.
What veins can provide a pathway for bone metastasis?
Intercostal veins that anastomose with vertebral veins.
Branches of what nerve primarily innervates the breast?
intercostal (thoracic) nerves
Branches of the supraclavicular nerve innervate what aspect of the breast?
Superior and lateral
Originate in the interlobular connective tissue and the walls of the lactiferous ducts?
lymphatic channels
What part of the lymphatic channels drain the breast?
superficial channels
What percent of lymph drains into the axillary chain?
> 75%
How many nodes are in the axillary chain?
30 to 40
The axillary nodes are further subdivided into anatomic groups and correspond to the nearest major vessel. these groups are:
External mammary subscapular axillary (lateral to ax artery) central (medial to ax artery) subclavicular intrasectoral (Rotters)
Nodes lateral to pectoralis minor muscle are what location for surgical classification?
level I, low axilla
Nodes deep to pectorals minor muscle or between med and lat boarders, including Rotters nodes, are what location for surgical classification?
Level II, mid axilla
Nodes medial to pectoralis minor and subclavicular nodes are what location for surgical classification?
Level III, high axilla
Breast tissue responds to hormones produces by?
Ovaries, hypothalamus and pituitary gland, placenta, thyroid, and pancreas
Hormone responsible for ductal proliferation?
Estrogen
Hormone responsible for lobular proliferation and growth?
Progestrone
Hormone present during late pregnancy and lactation?
Prolactin
What organ produces estrogen to stimulate growth and division of ducts?
Ovary
What organ produces progesterone to stimulate an increase in size and number of lobules and maturation of acini?
Ovary and placenta
What hormone and gland prevents release of prolactin until milk production is needed?
Hypothalamus
Prolactin Inhibiting factor
What gland releases prolactin to stimulate acini to produce milk?
Anterior pituitary
What hormone and gland initiates contraction of ducts for flow of milk during lactation?
Oxytocin
Posterior pituitary
Placental lactogen and HCG are produced by what?
placenta