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Structure and Function
Tits have a fairly basic structure. It all centres round the nipple:
- The nipple has a hole in it, through which milk can be squirted. The hole opens onto the...
- Lactiferous duct, which is a tube that leads to the...
- Lobular ducts, which are more tubes, that lead to the...
- Lobules. These contain acini, which are the secretory ducts that produce milk.
- Finally, it's all wrapped up in the fatty connective tissue.
There is only really 2 key functions of the breast:
- Milk production and release
- Slightly awkward paperweights
The process of milk production and release occurs during breastfeeding:
- During pregnancy, prolactin is released, and this stimulates the growth in duct tissue. However, the presence of high levels of progesterone inhibits milk production.
- After birth, the placenta pops out, and with it the progesterone levels plummet. This means that the acini begin pumping out milk.
- Next the baby sucks the nipple. This causes a release of oxytocin, which stimulates contraction of the cells around the acini, causing milk to be expelled into the lactiferous ducts. This is then sucked out into the baby's mouth.
- After a few days, the oxytocin/nipple feedback system fades away, and the milk release/production is directly related to nipple stimulation.
Arterial and Venous supply
Supply mainly from the internal thoracic artery and lateral thoracic artery. Drains mainly to the internal thoracic and axillary vein.
T4-T6 innervation. The nipple is in the T4 dermatome.
This is important in breast cancer! The majority of the drainage (75%) is to the axillary lymph nodes. The rest drains to the parasternal and abdominal nodes.