The pelvis is made up of three bones—two hips and the sacrum, a triangular bone that fits inside a shallow groove in both hips. These three bones comprise the sacroiliac joint (the ilium is one of three bones that fuse in infancy to form the hip. The ischium and the pubis are the other two). The sacroiliac or SI joint is among the most important in the body. A fully functioning spine requires space and movement within the SI joint. The SI is a gliding joint and ideally the sacrum is free to move up and down oh so slightly within the grooves of the hip.
A successful backbend requires this space and movement. The point of the two prior posts on the feet and the knees in backbends was to point out that if they are not successfully aligned these all important joints will be compromised and the spine won’t be able to lengthen as designed.
There is a length of connective tissue (fascia) called the iliotibial band (ITB) that connects the aforementioned ilium to the tibia, the big bone of the shin. There is a small muscle connected to the IT band called the tensor fasciae latae, or TFL.
The tensor fasciae latae as its name suggests, tenses the outer fascia (fasciae latae) and works to flex, abduct (pull away) and internally rotate the hip. The big gluteus maximus has two portions one of which connects into the ITB. The gluteus maximus in its connection to the ITB works to abduct the hip. The other possibly more important portion of gluteus maximus controls its main function as an extensor of the hip.
It seems to me that there is a battle for the ITB happening between the Gluteus maximus and TFL. The ITB needs to be able abduct and internally rotate for the body to work correctly. Both of these muscles help with abduction, the drawing of the leg out to the side, while only the little TFL has the job of internal rotation (with the help of well toned inner thigh muscles). Abduction alone will squeeze out the available room in the SI joints.
The IT band is a source of misery for people of all stripes—athletes and the sedentary alike are afflicted. Anyone with “tight” hips is almost garuanteed to be tight in the IT band and the TFL. I think almost all ITB band issues are a direct result of an insatiable need to tuck our pelvis under, which draws the ITB and TFL into external rotation rather than the neutral position that it is designed to be in. If the ITB is in this neutral position the TFL is free to internally rotate when called upon to do so.
Back to backbends. For the SI joints to be free and mobile the TFL must internally rotate when you go into wheel pose or any backbend. To return to the earlier posts again, the feet and knees must be aligned for the ITB and TFL to work as intended. It is the internal rotation of the TFL that helps to expand the back of the pelvis creating space for the SI joints, freeing up room for the sacrum to glide up or down in the groves of the hips.
If the feet are not grounded inside and out and the knees are not aligned over the ankle, the legs are pulled wider apart and we lose the ability to create internal rotation in the TFL and the likelihood of compressing the SI increases exponentially.
This post has gone on long enough so I will save other pelvis connections to the backbend (psoas, inner thighs, gluteus maximus)for future posts. I’ll finish by reiterating the need for free and open sacroiliac joints. I can’t state enough how important this is for yoga and life.