Did you ever realize that muscles do more than one thing, depending on how the body is positioned? Many times when we learn about what muscles do, we focus on their main function. So, for instance, the hip flexor muscle, the psoas, flexes the hip, like in the bent leg here in Reverse Warrior:

When the hips are in extension, the psoas stretches, like in Upward Dog, here:

Another muscle, the piriformis, externally rotates the hip, like the bent leg here in Extended Side Angle, where the left leg is in flexion and external rotation and the back hip is in extension.

One thing I never understood though was the reference to Figure 4 pose “stretching the psoas.” Figure Four looks like this:

I thought, “The right leg here is in external rotation. So the piriformis is CONTRACTING. How can this pose be stretching it?” 

But then I did some research and found out that when the hip is flexed past 90 degrees, the piriformis shifts from being an external rotator to being an INTERNAL rotator. That’s why in this pose, the right piriformis is stretching.. the hip is past 90 degrees of flexion! Here’s the NASM article that details it.

Friends, as you dive into anatomy, always be asking questions and look for the answers. This is one of the best ways to learn!

What’s something about anatomy you recently learned that surprised you?

Looking for a fun and easy way to learn some anatomy? Take my “Learn Anatomy Challenge” and don’t forget to download the yoga sequencing template that goes with it! It’s a free video series that will walk you through lots of great information. Get it here.

Thanks for reading!