Anatomy of Breast Flashcards
Which quadrant is most likely to have cancerous tumours?
Superior lateral
Due to axillary process making it the largest quadrant
What is the arterial supply of the breast?
- Perforating branches of internal thoracic
- Mammary branches of lateral thoracic
- Mammary branches of intercostal arteries
Where do the veins of breast drain into?
Axillary + internal thoracic vein
Where do the lymphatic from breast drain?
Mostly axillary nodes
What is the innervation of the breast?
Anterior + lateral cutaneous branches of 4th-6th intercostal nerves
N.B Nerves DO NOT control milk secretion
Which connective tissues support the breast?
Fibrous CT = Coopers ligaments
What tissues are the breast made of?
Glandular + adipose
Why is it easier to pick up tumour shadows in elderly females?
As females age, breast loses some glandular elements + becomes less dense on mammogram
Describe breast development
- Until puberty, immature breast = rudimentary lactiferous ducts
- Oestrogen stimulates ductal elongation + bifurcation
- Progesterone stimulates formation of spherical masses of epithelial cells at end of each duct
What is the lobes, lobules and duct system of the breast?
- Each breast divided into lobes by fibrous septa
- Lobes drain into 10 major lactiferous ducts
- Lobes divide into lobules - each contains certain no. alveoli + ducts
Which cells produce milk?
Acini cells in alveoli
Contraction of myoepithelial cells squeezes alveoli and ejects milk
How many lactiferous ducts are there?
10 major ones
What changes take place during pregnancy?
- Increased size due to hypertrophy + prolif. of ducts (oestrogen) + alveoli (oestrogen + progesterone)
- Terminal alveolar cell differentiate into secretory cells
- Sebaceous glands become hypertrophied = Montgomery’s tubercles
What happens in stage 1 of lactogenesis?
- Prolactin usually inhibited by dopamine
- Oestrogen acts at hypothalamic level to increase prolactin secretion
- Lactose, casein and alpha-lactalbumin
- Full milk secretion prevented by increased levels of progesterone (interferes with prolactin)
How do you treat breasts engorged with milk due to termination after week 22?
Administer dopamine agonist
What happens in stage 2 of lactogenesis?
- Birth = sudden drop in oestrogen, progesterone + hPL
- Increase prolactin = cue
- Increase milk vol
- Increase in lactose, IgA, lactoferrin + oligosaccharide
What happens in stage 3 (glactopoiesis) of lactogenesis?
- Suckling coordinates release of prolactin (anterior pituitary) + oxytocin (posterior pituitary)
- Switch from endocrine to autocrine control (due to placental removal)
What is galactokinesis?
- Discharge of milk during suckling + contractile mechanism expresses milk from alveoli > ducts
- Suckling increases release of prolactin + oxytocin
How is the release of oxytocin from posterior pituitary stimulated?
Impulses passes via spinal cord + brainstem to hypothalamus
How is excess milk production prevented in galactopoiesis?
Prolactin uptake inhibited in full alveoli
Alveolus full of milk > walls expand + alter shape of prolactin receptors > reduced milk synthesis
What is the fat content of milk determined by?
How empty breast is
Emptier breast = high fat milk
What infant risk factors impair lactation?
- Birth by vacuum
- Tongue tie
- Hyperbilirubinemia
- Hypoglycemia
What maternal risk factors impair lactation?
- Total labour 14+ hours
- C-section
- Inverted nipples
- T1D
- Obesity
- Multiple births
- Smoking
How can breastfeeding act as a contraceptive?
- Lactational amenorrhea
- Supresses ovulation
- Disrupts pulsatile release GnRH from hypothalamus and therefore LH from pituitary
