5 Body Parts You Didn't Know You Had

Sit Bones, Sacrum, Psoas, Piriformis, and Intercostals

Do you know your piriformis from your psoas from your sit bones? Yoga introduces you to body parts you never knew you had. And once you know about them, you can stretch them out as well as use them to help improve your balance and alignment.


The Sit Bones

The pelvis

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You may hear them called sits bones, sitz bones, or sitting bones. Chances are you didn't hear of them at all until your yoga teacher told you to sit on them. Anatomically part of your pelvis (the ischial tuberosity, to be exact), the sit bones are quite literally the bones under the flesh of the butt that you sit on. When you sit up straight, you're balancing on your sit bones. You might not realize it, because that area is a little fleshy thanks to the gluteus muscles. Yet, if you gently rock back and forth while seated, you'll notice a difference and can feel the sit bones.

The Yoga Connection

The sit bones affect your posture in seated positions such as cobbler's pose and seated forward bend. Balancing on the sit bones helps elongate your spine and distribute your weight equally on both sides of the body. To do this, sit up straight and try to feel the sit bones on either side of your pelvis pressing into your mat. You may even push the flesh of your butt to the side and out of the way.


The Sacrum

Sacrum, illustration

The sacrum is the triangular bone at the base of your spine, right above your tailbone. It is a common source of lower back pain and home to a number of nerves. It connects to the hip bones via the sacroiliac joint (SI joint). This SI joint can become misaligned and is a common source of pain. Ask your yoga teacher about ways to mitigate and prevent this, particularly if you've injured it before.

The Yoga Connection

The sacrum is stretched and twisted in a number of yoga poses, and it's easy to take it too far. In poses in which you are lying on your back, the sacrum should usually stay down. Your teacher will likely remind you of this often, telling you to "protect your sacrum" and to move slowly and deliberately.


The Psoas

The Psoas Major Muscle
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The psoas major is one of the groups of muscles that are called hip flexors. These work together to bring your leg and torso toward one another into a position of flexion (like a crunch).

The psoas (pronounced "so-az") inserts in the upper interior of your femur (thigh bone) at one end. It then passes through the pelvis and connects to several of the lower vertebrae as it fans out at the other end.

Since the psoas is not a surface muscle, it can be difficult to identify and isolate. Its anonymity does not decrease its importance, though. The psoas is key to the cultivation of core strength and hip flexibility. Strengthening and lengthening the psoas is key for anyone suffering from back pain due to sitting too much.

The Yoga Connection

The psoas is particularly important in balancing as well as bending forward and backward. Poses for the psoas include tree pose, standing big toe pose, king dancer pose, and warrior I pose.


The Piriformis

The Piriformis Muscle

Running right behind the psoas (figuratively, and somewhat literally) for the title of least famous muscle is the piriformis. It's possible for this little-known muscle to become either too tight or too loose and cause all sorts of pain. Stretching this little muscle in your butt can have a big impact if you're dealing with sciatica.

The Yoga Connection

The piriformis is a key muscle in leg rotation, allowing you to turn it outward from the hip. It is also a key to the support system for the sacrum. When your teacher offers suggestions to improve pelvic alignment, the piriformis is often the target.


The Intercostals

External intercostal muscles
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If you have ever felt sore around your ribs after a lot of back bending or twisting, your intercostals are talking. These muscles are responsible for the expansion and contraction of your rib cage when you breathe. They not only allow the lungs to expand and contract, they also affect your posture.

The Yoga Connection

The rib cage plays a big role in your practice. Poses such as cow face pose and gate pose can do wonders for stretching and opening up the intercostals. It's easy to neglect these, but the chest muscles are just as important in yoga as any other muscles.

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