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Nutation and Counter Nutation

 
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bonnieylau



Joined: 27 Nov 2018
Posts: 2
Location: Ontario

PostPosted: Tue Dec 18, 2018 2:23 am    Post subject: Nutation and Counter Nutation Reply with quote

Hi Bernie!

Reading through the Your Spine Your Yoga book, and i am currently on the sacral complex. My question for you is if you could
a. describe a bit more about nutation/counter nutation specifically, why does the sacrum counter nutate in a prone position. (page 54)
b. is it accurate to say then, that nutation = an anterior pelvic tilt?
c. when you forward fold, your pelvis moves forward ( i presume), so what happens to the sacrum? Is this nutation or counter nutation?
d. From my understanding of the book, it sounds like too much nutation or too much counter nutation isn't good, is that correct? I guess it really all depends? ... In the book you mention that too much flexion (nutation) at the SI joints isn't good [pg 54], and you also mention that counternutation that in supine or prone positions, that counter nutation makes the joint more mobile [pg 55].

Thank you! Much appreciated!
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-Bonnie Lau
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Bernie



Joined: 23 Sep 2006
Posts: 1021
Location: Vancouver

PostPosted: Wed Dec 19, 2018 1:41 am    Post subject: Reply with quote

Hi Bonnie … good questions: movement at the sacroiliac joints (SIJ) have confused many people, myself included. It is helpful to remember we are strictly talking about the relative movement of the sacrum and the pelvis. Pelvic motion by itself doesn’t mean that there is movement at the SIJ. Sacral movement also does not mean that there is movement at the SIJ. One has to move with respect to the other in order for nutation or counternutation to occur. If the top of the sacrum moves forward against a stationary pelvis, that’s nutation. However if top of the pelvis moves backward (pelvic tuck) against a stationary sacrum, that is also nutation. Opposite movements are called counter nutation. (See the illustrations on page 80.)

So…for your questions:

a) Why does the sacrum counter nutate when we are lying down? This is discussed on page 81: when unloaded, the tension in the ligaments tends to counter nutate the sacrum. In a prone position it may also be due to pressure from the floor pushing the top of the sacrum backwards.There is a link in the footnote #377 to a detailed study of this movement.

b) No, that is not correct. Movement of the pelvis is just movement of the pelvis. Nutation is movement of the sacrum relative to the pelvis.

c) Just because the pelvis is moving forward, which creates flexion at the hip sockets, does not necessarily mean that there is movement at the SIJ. There may be, but if the sacrum is moving at the same time, in the same direction, there may not be. Or, the sacrum may be moving more forward than the pelvis in the same direction (nutation) or moving in the opposite direction (counter nutation). So, it depends upon what both bones are doing relative to each other. You can’t focus on just one bone. Flexion at the hip joints (pelvis moving forward as you call it) is shown on page 89 in figure 3.124c. Normally the sacrum moves more than the pelvis which causes nutation. But that is only the case for 45% of the population! (See table 3.104.) For 28% of people no movement between the sacrum and pelvis occurs and in 28% of people there is counter nutation! So, beware of making dogmatic statements such as “Folding forward always causes nutation!” It depends on the person!

d) The main point to understand is that there is very, very little movement occurring at the SIJ. This joint is meant to stabilize the sacral complex and thus the tiny amount of movement that does occur is to release the stress in the whole bowl when it gets too high. Our intention should be to maintain this stability, not to increase mobility here. However, in rare cases, some people are too mobile in their SIJ: they need to work on more stability. Even more rare I believe are people who have too little mobility here and need to work at getting that back.

I think if you re-read the section starting on page 80, this will become more clear.

Cheers
Bernie
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bonnieylau



Joined: 27 Nov 2018
Posts: 2
Location: Ontario

PostPosted: Thu Dec 20, 2018 4:27 am    Post subject: Reply with quote

thanks Bernie! It's most likely because i wasn't at page 80 yet but having referenced them now, it's making a bit more sense.
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