Your Fexible Pelvis

Yesterday this flexible pelvis model arrived. It got me thinking.

Imagine you are in a dark cave. The only way out is through this opening...

At first the walls of the opening appear to be rigid, like stone. But what if they are not?...

What if there are places in the walls of the cave that will move, that can flex and shift if you push against them?

What if someone on the outside of the cave could help you by actively moving these pieces changing the shape and size of the passageway you are trying to squeeze through? What if?...

We are looking through the bony cave that your baby will fit through. We are looking at it from the direction of the top of your baby's head, from above your pelvis, rather than the direction midwives and doctors look at it, from below. At the bottom of the picture is the sacrum bone. The two illia, or hip bones attach to the sacrum and create the sides and front. They wrap around and meet each other at the pubic symphysis  joint at the top of the photo.

Here is the same pelvis from the side. Notice the angle of the sacrum pointing down with the tail bone the sharper point at the very bottom. My hand is holding the pubic synthesis. Notice the shape of the opening in each of the photos.

Now let's go back to our cave with the flexible walls. Bones aren't flexible right? Well actually bones have more flex than we imagine. They are living tissue. When they are alive, versus hanging in a skeleton, they have more ability to move. Plus there are joints! Your pelvis has 4 joints; the pubic symphysis at the front, 2 sacroiliac joints at the back, and the joint between the sacrum and tailbone. All of these should be able to move or shift. Your baby can move them by pushing against them and YOU can move them by activating certain muscles and deactivating others. Certain body positions can either allow or enhance this movement.

Let's look at the shape of our cave if we move the sacrum in at the top and out at the tailbone end.


Wow there is a lot less space at the top, the inlet of the pelvis. The cave just got really tight if I am just beginning to wriggle through but...

Look what happened at the opening at the outlet of the cave! Way more room.

Now let's see what happens to the shapes if we move the sacrum backward at the top. Or our pelvic floor muscles are pulling the bottom third of our sacrum and our tailbone forward.

It is a little hard to see in this photo but the distance from pubic symphysis to top third of sacrum is much longer. So the bone moved out of the way of baby getting INTO the cave but what happened to the outlet of the cave?...









YIKES! That's going to be one tight fit.

In actuality my "flexible" pelvis model isn't nearly as flexible as YOUR pelvis. Your sacrum doesn't just tilt forward and back. The whole sacrum can also shift left and right. It can tip left or right pointing your tailbone either left or right. It can also rotate or tilt taking one side closer to your pubic symphysis and the opposite side further away. To learn more about the mother/baby birth bone dance  and how Moving Toward Ease sessions can help prepare your pelvis to move during birth visit my Moving Toward Ease page.