Breast anatomy: the last 20 years
With the fantastic amount of information available about the human body, how it works and how to fix what doesn’t work, it amazes me how little knowledge there has been around breasts and breastfeeding.
The diagram of breasts found in every anatomy and physiology text published before the early 2000‘s were drawn 170 years ago by Sir Ashley Cooper from dissections done on lactating breasts from women who died after childbirth.
About 10 years ago, a team at the University of Western Australia compiled data using breast ultrasound images and revealed four major differences (from the accepted diagrams) in our understanding of breast physiology:
•The lactiferous sinuses or milk reservoirs shown in Cooper’s drawings do not exist. What has been observed is that milk ducts expand easily and then contract again. Most likely the hot wax Cooper injected in milk ducts for the dissections artificially expanded milk ducts near the nipple. Thus they showed up in his drawings as static “storage” spaces.
•Glandular tissue (that makes the milk) is found closer to the nipple than was shown on previous drawings.
•Milk ducts begin branching just behind the nipple and resemble the tangle of tree roots more closely than the neat radial drawings have shown.
•Duct diameter varies greatly, expanding with the flow of milk, but also varying from woman to woman. In addition, some ducts are situated very close to the skin and are easily compressed, even enough to block the flow of milk.
This is all interesting, but what does it mean for a mom?
Moms are interested in how much milk there is and getting the milk out.
•Since milk is not being stored in reservoirs right behind the nipple, the milk ejection reflex takes on an even larger role in moving milk out of the breast. We need to know how to trigger additional milk ejections to maximize milk output.
•Duct diameter can vary from mom to mom. Mom’s with larger ducts will get more milk out more quickly. That is not to say they will make more milk, just that it will move faster.
•Since milk ducts are compressed easily, it is important the flanges used while pumping are fit correctly. A too-small flange can restrict the flow of milk.
Understanding the underlying structures in the breast help lactation professionals analyze the coordination between baby’s suck and mother’s milk flow to help identify causes of nipple pain or low weight gain.
So breasts haven’t changed, of course. But we know so much more now about how to help moms who struggle with breastfeeding. It’s an exciting field of science.