Anatomy of the spine – connected by the waist

In the second of her anatomy series, Dawn looks at how fascia and the breath support our structure and moves up the spine to explore the T12 area.

back anatomy

In my previous article in this series, we had a look-see-feel around our pelvis and our lower back. We walked through the ‘bony landmarks’ and talked through some of the function of the pelvic-lumbar region. We started on the musculature and the discs between our vertebrae.

This time we’re going to expand on the fascia and the breath – yes, the breath has a role to play in your back health! – and we’ll start moving up the back a little and reach to around the base of the ribs.

Our muscles form a continuum

We’re conditioned to think about our bodies in a compartmental way – “this is my pelvic ‘floor’, then these are my stomach muscles, then my back muscles” and so on. However, our muscles form a continuum, they all merge.

Your pelvic muscles (as I prefer to call them) merge into your lower abdominals, they merge into the tops of our thigh bones too. Our lower back muscles arise from our pelvis and wrap around our trunk merging into our abdominals. Granted, there are distinct muscle bellies and different sets of muscles have different functions and directions of action, but what we know is that for every task we carry out several muscles will get involved.

Muscles are team players essentially, and what’s more, they’re all connected by our ubiquitous fascia.


Fascia is the silk-like web that wraps around each of the muscle bellies as well as between them, over the top of them and underneath them. It is this web that forms the continuum. Fascia is the slowly contracting-and-relaxing tissue that forms our posture.

In the last article I mentioned ‘tight hamstrings’ and suggested that your tight hamstrings might actually be the result of a limitation in your lower back. But more accurately, it’s the hold of the fascia that sits over the lumbar region which will be responsible for the restriction in the pelvic-lumbar complex and consequently why you might not be able to touch your toes.

The slow-release characteristic of your fascia is why the pelvic-rocking exercise from Lisa Petersen I recommended is a slow-burner in terms of freeing your lower back. Slow and steady persistence rules here!

Our breath supports our structure

We talk so often about the breath in our yoga, but do we really realise how much of a role it plays in supporting our structure?

That sounds like a paradigm shift: “the breath? Supporting our structure?!” but it’s actually more of a diaphragm shift : )

We have 3 muscular regions that work as diaphragms. There is our respiratory diaphragm, that we’re all familiar with, our pelvic ‘floor’ and our thoracic outlet (the musculature that sits over the top of our lungs). When our three diaphragms are happily working together they operate in conjunction to coordinate the free moving of the breath. It is this which provides intrinsic support to our lower back.

The support comes from the change in the pressure within our abdomen, and it’s a very clever mechanism of the body. We use it all of the time in our yoga to support us as we move into and out of our yoga postures.

It’s essential that we allow the support mechanism offered from our free moving breath, rather than restricting it by ‘locking down’ our tummy muscles in order to move. If we do the latter, we restrict our movement with our muscles and disturb the natural mobility of the breath. We’re likely to end up with just the opposite of what we thought we were protecting ourselves against – lower back pain!

I am wholly convinced that this aspect of yoga – proper utilisation of the breath – is what happens for all those who start yoga and suddenly find that their back pain has resolved. No doubt some strengthening of the core muscles has also taken place (and possibly there is a belief that this has resolved their back pain). But I personally suspect they’ve started to trust that the breath will support their back when they move, and it is this that allows their back pain to ease away.

It’s very powerful (figuratively as well as literally), and I think that it’s largely not talked about in our yoga classes. The support of the breath is certainly an absent element in our medical system!

T12 and the twelfth ribs

So, back to the structure of the spine. In the last article we covered the lumbar spine, now we’re moving up the spine a little to where the lumbar spine and the thoracic spine meet at our twelfth thoracic vertebrae (T12) and our twelfth rib.

The twelfth rib at T12 is quite a key player. It’s the junction between the lumbar spine and the thoracic spine, and in yoga it’s where we really start our rotations. When we think about lengthening the spine and then rotating around in a seated twist, the twisting occurs around T12. T12 is also a key mover in our side bends. It’s also where our legs start!

Arm and leg muscles in your back

Our twelfth rib attaches to T12, it’s known as a ‘floating rib’ because it doesn’t attach to the sternum. It is a busy old rib: the psoas part of the ‘ilio-psoas’ arises here and the quadratus lumborum (the QL) also attaches onto T12.

The iliopsoas is a ‘hip-flexor’ muscle fundamentally. It originates in the back of our body, and then wends its way down through the pelvis, (where the iliacus merges into it) to the front of the body. When the pelvis is ‘free’ (read: mobile), the action of walking starts from the back of our waist at this ‘thoracolumbar’ junction.

Have a go! Jump up and place one of your hands to the back of your ‘high waist’ and then start to walk.

Can you feel the muscles activating underneath your hand? If so, fabulous. If not, try this – try walking as if you’re on a catwalk! I’m not kidding – start strutting your stuff, get your hips swinging forwards and backwards and then you’ll kick-start this movement.

Then the trick is to work out how to keep the muscles moving without the swagger!

The quadratus lumborum’s function is to flex us from side to side. It can be a little devil though and it can be implicated with all sorts of disparate aches and pains throughout the body. If we’re super tight in our QL, it can make us flare out our front ribs when we’re standing in Tadasana, amongst other things.

What’s more about the twelfth rib is that one of our arm muscles attaches on to the back of our waist too – the latissimus dorsi (or your ‘lats’). Yes, an arm mover starts all of that way down our back! I told you it was a busy old location…

Wriggle for freedom!

The back of the waist – this T12 region – is so important to our comfort and mobility, and not just in our yoga. We move in three planes. Our spine moves forwards and backwards, side to side and round in a rotation.

It’s very important that we work into these three directions with our yoga poses to keep us optimally mobile, and to free the tissues that hold us in our usual movement patterns. Sometimes the best way to do that is to just have a wriggle!

Wriggle in your cat-cow, definitely wriggle in Downward Dog (or, ‘walk it out’!) and explore the spaces along your spine with your movement. Your back and your muscles will certainly thank you for it!

More on this subject:

The Psoas, Iliacus, Quadratus Lumborum and Piriformis – connecting the back and hips 

More from Dawn’s anatomy series

About the author: 

Dawn Meredith-Davies MSc is a holistic physiotherapist, yoga teacher and writer. Having practised yoga for over 15 years, Dawn incorporates this in her clinic work together with hands-on treatment, acupuncture, nutrition and the all-important breath.
When she’s not on the mat, getting outdoors and running is Dawn’s mainstay. As a specialist in movement analysis for running, Dawn brings together all of these tools, as well her professional practice, her love of writing and sharing the good stuff at her Living Green Health website to help you run, breathe and live green! 

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Dawn Meredith-DaviesHolistic physiotherapist, running movement specialist and yoga teacher, Dawn Meredith-Davies has spent over a decade utilising the powerful benefits of yoga to help others heal from their pain (or to improve their running!). Find her over at where she shares her knowledge about our interconnected experiences.