I am honored that David Keil took the time to comment in the recent post asking about nutation and answered at length.
I wanted to share with everyone what “The Bone Man” as he calls himself is sharing. Thank you! and also I would like to thank Tova for asking him
Nutation and counter nutation are movements that happens at the sacroiliac joint, that is where the sacrum meets the two sides of the pelvis. Nutation (from neutral again) is where the top part of the sacrum would move down and forward relative to the pelvis being fixed in place. Kapandji referenced above describes this as the sacral base moving forward and down. Counter nutation is simply the opposite.
“The Bone Man”
Female pelvis picture comes from here