Hi. Please explain the differences between the inner corset and the rib anchor to someone who is not strong in anatomy. Please include location, function, and when to use each. Thanks.
The rib anchor is essentially a reminder not to let the ribs flare out, the other is a way of engaging your deep abdominal muscles in order to stretch and protect your spine.
You want to think about anchoring your ribs even when you might not be actively engaging your inner corset, for example when you stretchsit or stretchlie. It's a fairly passive movement. You want to think about engaging your inner corset when you bend, lift objects, and generally participate in physical activity. It's a very active movement.
Notice that the book avoids asking people to "engage the core." These muscles do have some overlap, but by engaging specifically the upper abdominals with the rib anchor and inner corset, you allow the lower abdominals to stretch out, which prevents both a tucked pelvis and a sway back.