Yoga Art: Low Back Anatomy lesson + Layers in Torso Skeleton

Gibbon Skeleton-- torso, pelvis, shoulders, and skull anterior view

Comparative anatomy is cool. When you look at the anatomy, form and function of another species, you can gain insights into the human body in ways we may have overlooked or ignored. Invisible characteristics become relevant and significant.

Since form is function, our anatomy will effect our biomechanics, both in and out of yoga asana (poses). Biomechanics affects performance, posture, and pain.

For my recent research project on gibbons I was studying their skeletons and how they are adapted to gibbon life and reflect gibbon evolution. I was also looking at how they move (especially how they “brachiate”, or travel through the trees by swinging from branch to branch). This research on gibbon skeletons, led to research on chimpanzee skeletons which led back to features on the human skeletons.

I wanted to share with you one of the interesting tidbits I found which is relevant to your yoga practice or movement practice and which could be especially beneficial for yoga teachers.

Learning from gibbons

The anatomy of the lumbar spine — our special waists

Think about your lumbar vertebrae, the spine of your lower back. The lumbar spine is bounded by the thoracic vertebrae above and the sacrum below. Both are nestled into relatively immobile structures: the ribs and ribcage limit the movement of the thoracic spine and the sacrum (which is actually sacral vertebrae which have fused together) is nestled into the two sides of the pelvis.

Gibbon Skeleton-- anterior torso: ribcage, lumbar spine, and pelvis space

Human Skeleton-- anterior torso: ribcage, lumbar spine, and pelvis space

Photos I took of Gibbon and Human Skeleton. Note that in both species there is a physical separation between the ribcage and pelvis.

Notice that there is space between your ribs and your sacrum. Human waists are tall and narrow (well, most of us). Compare this to chimps, whose waists are short and wide. Other animals barely have waists. They have very little space between ribs and pelvis. Chimps’ lumbar spines are shorter than humans (relative to their shape). Humans skeletons are built so that their lumbar spine is not restricted. The tall, skinny human waist separates the ribs and pelvis so that the waist is free to move.

[nerdy anatomy aside: this narrow tall waist is adapted to bipedalism. The freedom to move means that the waist can twist, which allows the torso to twist in opposition to the pelvis. This allows the body to balance angular momentum while running.]

[nerdy technical aside: note that all the size comparisons, such as "tall" and "wide"are relative. These descriptions relate to the expected size of a waist or length of a lumbar spine when you scale skeleton to a different size. During scaling, characteristics may not scale linearly, for example volume and length do not scale equally if the shape remains proportionally the same. When a characteristic is larger or smaller than predicted, we can ask why the skeleton breaks isometry or any other predictions. For further reading, look up allometry or isometry.]

So, the lumbar vertebrae are not limited in movement by other bones. Sure, the shape of the lumbar vertebrae determine the range of motion of the lumbar spine (more flexion and extension than twisting). However there is no boney structure or cylinder (ribs, pelvis) limiting movement.

Why does this matter?

The blessings and pitfalls of mobility and flexibility

the freedom from bone means the human lumbar spine is highly mobile. Also the soft tissues and organs around the lumbar spine can move, twist, and bend as your body needs for motion. Extra space to move! Potential range of motion! You are not stuck.
the lack of extra bone architecture means the soft tissue (e.g. connective tissue, muscles, tendons, ligaments) have to do extra work to maintain the integrity of the low back. Imagine if you were all floppy in the waist and abdomen. The lumbar vertebrae could maybe hold you up if you stood vertically and balanced precisely. But now try to lean forward or to the side; the stress on your spine would be tremendous. You’d split in two.

So you need a strong “core”, 360 degrees around the low back–abs, quadratus lumborum, back muscles like erector spinae–to help the spine move and to support the low back.

If you sit all day at a desk or in a car, or your core is weak, your lumbar spine can become compromised. Your body will try to compensate for the weak core muscles. This compensation process can lead to bulging disks, low back pain, or a stiff low back.

On the other hand, we can thank our tall, flexible waists for more elegant walking/running gait, and flexibility in balance. The core muscles support us, but they can also coordinate complex movement patterns. Plus, we have the potential for a tremendous freedom of expression and movement, in yoga and in other activities (you can bend your back over a bar in olympic style high jumps!)

In short, our waists are special. Our lumbar vertebrae, or our lower back, are free to move because the ribcage and pelvis aren’t stuck together.

As a yoga teacher, this gives me some new ideas to work with. Alternate perspectives on the same situations often yield new insight. As I’ve been thinking about this anatomy in my yoga practice, expect to see some of the understanding gained to show up in classes.

And so anatomy inspires yoga.

About the photography and anatomy sketch:

I took the photos above while doing my research project at the Harvard MCZ museum. Great place to visit for locals. It’s been recently renovated (I think in 2009).

I’ve been experimenting with some digital art which is interesting because you can build up sketches as layers (a la photoshop). This is my first drawing ever on a new program so nothing fancy in this sketch of a torso and its underlying skeleton. I always enjoy drawing anatomy because it gives me insight into the relationship between structures and their ramifications in yoga. More yoga art can be found on my blog.

Since this drawing was built up in layers, I’ve taken parts apart for your edification. Let me know your reactions to the layering or just the skeletons in general.

Here I was also thinking about/had fun with:

The spine.
The way the top and bottom segments of cylindrical containers of the abdomen and thorax are held together. For example, lung diaphragm and pelvic diaphragm. Expressions of spines, sacrum, top and bottom elements.
And the communication and reflexion of the geometry of the lung/ribcage diaphragm and pelvic bowl shape/diaphragm. Also the implied shape of the atlas, the first ribs and clavicle. Even the curve implied by the greater trochanter of the femur and the bottom of the pelvis.
And human greater trochanters! (The angle of the femur. We are bipedal!) For another day…….

As always, I appreciate you meeting me here. Let me know of any feedback or questions.