Asana Anatomy -The Sacroiliac Joint

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By Dr. Robin Armstrong • August 28th, 2008

Asana Anatomy -The Sacroiliac Joint
Interestingly, a number of studies have shown that women who tear their ACL ligament in their knee are more likely to do so when they are ovulating.

The SI joints also gain support from the surrounding musculature. This is a concept known as Force Closure, discussed in a previous article. In particular the muscles of the pelvic floor: pubococcygeus, iliococcygeus, cocygeus, and the core transversus abdominis muscle - which wraps around the lower belly - can be very influential.

Wide Legged Caution
Poses like prasarita padottanasana (wide legged forward bend), baddha konasana (bound angle pose), and upavishta konasana (seated wide legged forward bend) can be a concern for people with a history of SI joint pain, and can predispose the SI joint to injury.

In wide legged forward bend we are simultaneously stretching the adductor muscles of the groin (attachments to the pubic bone) and the hamstring group (with attachments to the sitting bones). When we abduct (move the thigh bones away from midline) the adductor muscles pull on the pubic bones, gapping the SI joint space. This provides more freedom of movement for the SI joint, which may predispose it to moving excessively. The forward flexion component causes the hamstrings to pull on the sitting bones, which in turn stretches the sacrotuberous ligament whose job it is to counter motion in the sacrum. If one hamstring is longer than the other, this can also cause an asymmetrical strain across the SI joints.

One way to support the SI joint in the wide legged poses is to engage the muscles of the pelvic floor and lower abdomen. Studies have shown that contracting these muscles can help stabilize the SI joint by increasing the close fit of the sacrum with the ilium (Force Closure). The pelvic floor is more significant in women, but both men and women can benefit from engaging transversus abdominis. Tips to learn to engage these muscles are described below.

Engaging the Pelvic Floor
Sitting quietly, slow down your breathing. Feel the gentle inhale and exhale creating space and lightness in your body. Bring your attention to the muscles of your pelvis, particularly the muscles you would use to stop the flow of urine. Gently contract these muscles, lifting them up away from the floor. Then gently release. Repeat this action, keeping the natural flow of your breath. Try to contract the muscles closer to the front of your pelvis, rather than the muscles closer to your anus.

Now take this practice onto your mat.

Engaging the lower belly/ Transversus Abdominis
Lying on your back with your knees bent and flat on the floor, slow down your breathing. Notice the gentle rise and fall of your chest and belly as you breathe. Place your hands at your lower belly so that the heel of your hand rests on the bony front of your pelvis (known as the ASIS/Anterior Superior Iliac Spine). Gently draw your belly button in and up so that your lower belly flattens. Breathe normally. Try to keep your large, upper abdominal muscles (rectus abdominis) relaxed. Repeat, breathing normally.

Now take this practice onto your mat.

Mindful Practice
Wide legged yoga poses can be an excellent way to open the muscles of the groin, bring awareness to our root chakra, and release tension in the hamstrings. Much like any asana, when we proceed without being fully present and engaged - physically and mentally- we are at risk for injury. If we are mindful about engaging the muscles that support the SI joints, we are more likely to enjoy a wide legged practice that is safe and pain free.


Dr. Robin Armstrong is a Vancouver chiropractor and yoga instructor. Robin blends her western knowledge gained from her experience as a chiropractor, with the ancient eastern knowledge passed through generations of yoga teachers. Robin's classes emphasize safety, breath, alignment, and movement, while teaching students ways to strengthen and lengthen their bodies to handle the stresses of our modern lifestyle. If you are coming to her as a patient, expect to be prescribed yoga!
Visit Robin's website: www.stayactive.ca.

Dr. Robin Armstrong

Location:  Vancouver, CA

Dr. Robin Armstrong is a chiropractor and yoga teacher in the Kitsilano neighborhood of Vancouver.  Combining her two roles, she has taught yoga anatomy for a number of yoga teacher training programs as well as workshops...