Aloha zebra,
Chunyi either references the "sacrum" or mentions the Superior bone when talking about opening the flexibility to the whole body. I'll let him crack open Grey's Anatomy and flesh out the actual structure, since it's been a long time since I've been concerned with getting the "right" structure from him, and just focus the opening and healing of the entire sacrum in my sitting posture, small universe, and tailbone taps.
Much Love, Shawn
