Nutation & Counternutation
For proper perspective, think of nutation and counternutation as relative movement between the three bones of the pelvis rather than a relationship between the bones and the cardinal planes. It doesn’t matter what position the pelvis is in, the bones move in the same relationship to each other.
In a 2 dimensional (2D) perspective, nutation is defined as an anterior and inferior rotation of the sacral base relative to the ilium but, in a 3D perspective, it involves simultaneous rotation on an oblique axis.
Although traditionally, nutation and counternutation were considered to involve only the sacrum and ilium, the Serola Theory presents them as the core movement of the entire musculoskeletal system.
It is important to note that nutation and counternutation can occur bilaterally, during which both innominates move together in either nutation or counternutation, or unilaterally, during which one side will be in nutation while the other side is in counternutation. Please see videos under Normal Movement.