Your sacrum is the keystone of your lower body

Your sacrum is the keystone of your lower body

I think of the sacrum as the keystone of the lower body, which means: it’s pretty darned important. Remove a keystone from an archway and the whole thing falls apart. Got a sacrum out of whack? Yup, it’s gonna feel like your lower body is falling apart.

Found at the bottom of your spine, just above your tail bone, your sacrum is a boney triangle made up of five fused vertebrae. Because of its location, some people refer to it as your ‘tail triangle.’ In the Pilates world, contemporary teachers mention it quite a bit, so it can be helpful to learn a few things about it.

In this position, some folks will feel their sacrum more than others.

In this position, some folks will feel their sacrum more than others.


Lie on your back with your knees bent and your feet flat. Don’t press anything into the floor, just let your body do what it does naturally. Your sacrum is the bony piece sitting on the floor between your waistband and your tailbone. Technically, your tailbone isn’t part of the sacrum, since it can move independently. No, I can’t voluntarily move my tailbone, but I have fallen on it and knocked it out of alignment….




The five vertebrae that make up your sacrum are actually separate bones in children. During your teen years, these bones begin to fuse together, taking roughly 20 years to become a cohesive unit. Have you ever noticed that kids seem more bendable than adults? Yup, one of the reasons is that some solid structures that exist in adult skeletons haven’t yet formed in younger skeletons. The ‘soft spot’ or fontanelle at the top of an infant’s head is another example of this.  Any fans of the TV show “Bones” out there? This is the kind of thing that the main character looks for to tell the age of a skeleton.

Leonardo Da Vinci's Vitruvian Man

Leonardo Da Vinci’s Vitruvian Man


Remember the Vitruvian man? It’s Leonardo DaVinci’s depiction of a perfectly proportioned human. To be honest, there are very few perfectly proportioned people walking around – we all have our foibles. Ask me about my genetically short shins & forearms……I have a story for everything!

Geek that I am, I simply loved my time working in a massage school clinic, as it gave me exposure to so many different bodies. One of the first things that I noticed was that sacrums differ  widely from person to person. Some are wide, some are narrow, some are domed and some are flat.  Some are longer and some are shorter. Go figure, the length of the sacrum doesn’t necessarily correspond to the height of the sacrum owner. In general, men have a longer, more evenly curved sacrums than women, and parents frequently pass along the shape of their sacrums to their children. That also means that people of the same nationality often share a similarly shaped sacrum.


Since sacrums vary so widely, there are exercises where it’s important to allow for variance. If you’ve ever ‘bumped’ your sacrum during a sit-up or the Pilates exercise ‘rolling like a ball,’ you likely have a more domed shape to your sacrum — it literally juts out a tiny bit. You’re not doing the exercise incorrectly! Consider adding padding, like a thicker, spongier mat, to make the exercise more comfortable.


Sciatica can cause pain in your butt or down the back or side of your leg


Thirty five different muscles grab onto, or ‘attach’ at your sacrum, pulling on it from every imaginable angle. When you think about where it’s placed, it’s easy to imagine your low back muscles grabbing on at the top, your hip muscles attaching at the sides and your leg muscles latching on at the bottom of the sacrum. If any of these muscle groups is working too hard or too little, that imbalance of forces can throw off the placement of your sacrum causing low back tension or pain, or even sciatica. This is why I call the sacrum the keystone of your lower body – move the keystone and it affects everything else!

The good news about the placement of all these muscles and the connective tissue that attaches them to the sacrum: they’re easy to access with massage. Yup, this  is a common spot that we work on in many of my Pain Free Body workshops. You can treat your own sacrum and all the muscles associated with it in 5 minutes. Release this area of your body and BAM, you’re going to feel a huge release in most of your lower body.

Christine Binnendyk is a mobility expert at Nike’s World Headquarters in Beaverton, Ore.. Nike employees take her Pain Free Body workshops at the Nike Sports Centers. Public workshops are available through Portland Community College, Club Sport Oregon and other locations. Find her best-selling book “Ageless Pilates” on Amazon.