How do babies suck / swallow (feed) when breastfeeding?

Question

Anatomically?

Answer 1

When breastfeeding, the baby latches onto the breast, taking as much of the areole (dark pigmented area around the nipple) as possible into it's mouth.  His tounge actually cradles the areole and aids in the suckling process.  The nipple  fits to  the natural shape of the baby's mouth.  The baby's mouth works in a suckling motion to extract the milk from the breast.

It's a lot more work than sucking from a bottle, but it promotes healthy mouth development, so that the baby will be less likely to need orthodontic work later on.

Answer 2

It's instinct.