Breast anatomy

The anatomy of the human breast was fundamentally revised in 2005, overturning assumptions held since 1840.

Origins
The standard model of the human breast is largely based on anatomical dissections carried out on cadavers by Cooper and published in 1840 under the title “On the anatomy of the breast”.

This model is based on wax casts and dissections prepared by Cooper. The casting procedure introduced several artefacts. The injection of coloured wax into milk duct openings at the nipple inflated those ducts, giving the impression that near the nipple they expand into milk storage sacs called lactiferous sinuses. Also, in order to illustrate the milk ducts, Cooper – who had likened them to the intertwined roots of a tree – laid them out in an ordered manner for the artist to draw. This ordered lay-out has been copied into anatomy diagrams ever since.

Until 2005, Cooper's results had never been corroborated by modern investigative methods. Consequently, Cooper's model still underlies most practitioners understanding of the lactating human breast.

Revised anatomy
Recent anatomical research involving imaging the lactating breast using ultrasound technology have challenged a number of commonly accepted conclusions.

These findings on anatomy of the breast have important implications for the way the breast is cared for, especially during surgery.

The major differences between Cooper-derived models and Ramsay's work are:


 * 1) Milk ducts branch closer to the nipple
 * 2) Lactiferous sinuses do not, in fact, exist. They are an artifact of the wax injection process.
 * 3) Glandular tissue is found closer to the nipple.
 * 4) Subcutaneous fat is minimal at the base of the nipple.
 * 5) The external shape or size of the breast is not predictive of its internal anatomy nor of its lactation potential.
 * 6) The ratio of glandular to fat tissue rises to 2:1 in the lactating breast, compared to a 1:1 ratio in nonlactating women.
 * 7) 65% of the glandular tissue is located within 30 mm from the base of the nipple.
 * 8) Between 4 and 18 milk ducts exit the nipple (anatomy textbooks talk of between 15 and 20 lobes and milk ducts per breast).
 * 9) The network of milk ducts is complex, not homogeneous. It is not always arranged symmetrically, nor in a radial pattern.
 * 10) The milk ducts near the nipple do not act as reservoirs for milk.

Implications for breast care
Since the number of milk ducts in the breast is lower than previously believed, the loss of only a few ducts can seriously compromise a woman’s ability to lactate. In the old model, fatty tissue is undifferentiated. The reality is that there are three clearly defined areas of fatty tissue. There is more glandular tissue than previously believed, concentrated near the nipple, not evenly distributed in the breast.

Surgeons working with an understanding based on Cooper’s model inadvertently put the ability of their patients to breastfeed at risk. Women with previous breast surgery have a greater than threefold risk of lactation insufficiency when compared to those women without surgery. While interference with lactation is a theoretical risk of any surgery on the breast, a number of studies have demonstrated a similar ability to breastfeed when breast reduction/lift patients are compared to control groups where the surgery was performed using a modern pedicle surgical technique.