Because the spinal column has some 26 joints, there is a lot of movement possibilities for the spinal column as a whole.
It's easier to learn to feel the parts of the spine if you isolate them and practice moving each part slowly, smoothly and repeatedly.
Put your awareness on the part that you are moving while focusing on feeling the movement and doing it.
Of the parts of the spinal column, the thoracic spine is perhaps one of the more difficult parts to learn to feel, perhaps in part because the ribs attach to it.
You may be used to thinking of the ribcage (and thoracic spine) as relatively immobile structures. Think of it instead as a flexible structure that you can feel and adjust the shape of.
The lumbar spine is relatively easier to feel, however problems can arise if you haven't learned to differentiate movements of your lumbar spine from movements of your hip joint. It may help to think of the pelvis as an extension of the lumbar spine. When you move your pelvis relative to your ribcage you change the shape of your lumbar spine. When you move your thigh bones relative to your pelvis, then you cause a change at the hip joints.
Because the sacrum connects to the hip bones to form the pelvis, it's easy to forget that the sacrum is a major part of the spine. As such, you may find it helpful to view the sacrum as an extension of the lumbar spine in some contexts (say when moving your lumbar spine). In other contexts it may be more helpful to think of the sacrum as part of the pelvis. In either case, work at being flexible so that you can can change your categorization of the sacrum as needed.
The cervical spine is perhaps the easiest part of the spinal column to feel. The movements are relatively uncomplicated, and since we move our head a lot it may be easier to learn to feel the part of our spine that connects our ribcage to our head.
Each of the above spinal regions are made up of spinal vertebrae, which are the main building blocks of the spine. Each of these vertebrae (there are 24 not including the sacrum and tailbone) can move relative to the vertebrae above and below it.
They can turn, bend sideways, bend forwards and bend backwards.
Note that you may find it helpful to view the sacrum and tailbone as one unified unit or two separate units. But do consider the relationship between the sacrum and the lowest lumbar vertebrae when moving or feeling your spine.
If you do such movements slowly and smoothly and repeatedly you can learn to feel the individual vertebrae of your vertebral column and learn to control them.
One yoga pose that you can practice feeling your spinal column while bending it backwards one vertebrae at a time is cobra yoga pose.
When turning your head (twisting your cervical spine) first try to make both sides of your neck equally long. Focus on feeling each of your cervical vertebrae (there are 7 remember) and turn each one relative to the vertebrae below.
You can also turn your skull relative to the uppermost cervical vertebrae. Think of it as an extra large vertebrae at the top of the spine.
If your breathing is slow and smoothy, try moving your head as you breathe. Move your head forwards (the direction your chest is facing in) when exhaling and pull it back while inhaling.
Do this while holding the twist.
See if you can feel the vertebrae of your cervical spine moving as you do this action.
While side bending your neck continue to make both sides of your neck feel long, even the short side. Try to adjust the curve so that it is a smooth curve with all the vertebrae involved.
Try to feel each vertebrae tilting relative to the one below it.
As with the twist you can focus on moving your head back as you inhale letting your chest lift and forwards as you exhale letting your chest sink down.
The spinous process at the back of each cervical vertebrae help to prevent the neck from bending too far backwards, even so, the head is heavy and rather than letting it fall back, bend your neck slowly backwards.
Try feeling each vertebrae and tilt it backwards relative to the one below it.
To bend your neck forwards, use your longus colli muscles to bend your neck forwards and pull the chin in. This muscle attaches directly to the front of the cervical spine and upper thoracic spine. One way to contract it is to focus on "squeezing" behind your windpipe since this muscle is sandwiched between the windpipe and the cervical spine. Feel each of your cervical vertebrae and focus on tilting them all forwards relative to the vertebra below.
Once you've finished these movements, focus on feeling your cervical spine with your head upright. Put your awareness in the location that you previously felt your cervical vertebrae. From front to back the cervical spine is quite thick, it takes up about half (or more) of the front to back width of your neck. Imagine it or visualize the front of it just behind your throat passage.
To become more aware of your lumbar spine (it has 5 vertebrae), practice rocking your pelvis forwards and backwards while sitting. As you do so allow your lumbar spine to bend forwards and backwards. Initially focus on feeling your lumbar spine as a whole. Then focus on your lumbar vertebrae one at a time. Actually focus on the joints between each pair of vertebrae. Continue to bend your entire lumbar spine back and forwards but focus on one vertebral joint at a time. When you get a sense of one joint, move up to the next.
To side bend your lumbar spine while sitting practice lifting one side of your pelvis and then lowering it while keeping your ribcage upright.
The lumbar spine can twist though it's twistability is limited. Why might you want to practice twisting your lumbar spine? The muscles that act on your lumbar spine to twist it can work against each other to stabilize your spine against twisting. So by practicing twisting your lumbar spine you are actually practicing using the same muscles that can help to stabilize it. Plus, those same muscles when active can help you to feel your lumbar spine. In order to activate, muscles need an opposing resistance.
Twisting your lumbar spine while sitting or standing upright, that resistance is not going to come from body weight. If nothing else, it's going to come from opposing muscles. So the very act of twisting your lumbar spine (and this is assuming your aren't using your arms to drive the twist, nor is anybody helping you to twist) can help to strengthen it.
The thoracic spine has 6 movement possibilities:
After rocking the pelvis backwards and forwards to bend the lumbar spine, you can carry that movement into your thoracic spine (it has 12 vertebrae).
As your rock your pelvis forwards bend your lumbar spine and thoracic spine backwards, and then bend it forwards as your pelvis rolls back. Again start by focusing on the thoracic spine as a whole, and then narrow your focus so that you focus on one joint at a time. You can also focus on feelling the ribs moving with respect to the ribs above and below. Imagine your ribs and the thoracic vertebrae that they attach to as one unit. (This isn't quite true since most of the upper ribs attach between two adjacent vertebrae, but it serves as a good starting point.)
After moving your lumbar spine and thoracic spine together, you can also try isolating your thoracic spine. Focus on only bending your T-spine and ribcage forwards and backwards. The movements will be limited because of your ribs. However, if you focus on moving your ribs and thoracic vertebrae together, the movements may come easier.
Another way to isolate the T-spine is to focus on twisting the ribs and respective vertebrea relative to the ribs and vertebrea below. Note that the lowermost thoracic vertebrea does not twist relative to the lumbar spine so focus your efforts on the upper 11 ribs and their respective vertebrae.
To sidebend the t-spine, you can bend your ribcage to the side while lifting one side of your pelvis. As you lift the right side of your pelvis, bend your ribcage to the right so that you bend your lumbar spine and thoracic spine to the right.
Here's some anatomy of the spinal column to backup your understanding of the above movements
Should the pelvis be thought of as part of your spinal column? It does attach to the base of the spine and like the ribs it gives the muscles that attach to the pelvis leverage to act on the base of the spine. Plus, any movements of the pelvis affect the spine more or less directly in one way or another.
So I'll include it in my discussion of the spinal column.
The pelvis is an important structure not just because it acts on and connects to the base of the spinal column. It also connects the spine to the legs. And it is connected via the sacrum and lumbar spine to the ribcage.
The sacrum is the wedge of bone located at the bottom of the spinal column. It fits into the gap at the back of the pelvis, connecting the two sides of the back of the pelvis together at the SI Joint. It also connects the pelvis to the lumbar spine.
While seated (or standing) you can roll the pelvis forwards and backwards, tilt it from side to side. While standing you can also turn it left and right.
If you keep your lumbar spine relaxed while doing these movements you can move your pelvis independently of the ribcage. As an example, if rolling your pelvis forwards and backwards you can keep your ribcage upright. Meanwhile, as you roll your pelvis forwards or backwards your lumbar spine will bend backwards or forwards so that your ribcage remains upright.
If you keep your spine rigid using your spinal erectors and/or your abdominals then your pelvis and rib cage will move as one unit. While rolling your pelvis forwards and backwards your ribcage will tilt forwards or backwards with your pelvis so that the two move as one.
The lowest part of the spinal column is the sacrum. At the bottom of the sacrum, forming it's downward pointing tip, is the tailbone or coccyx. This bone supports one end of the pelvic floor muscles that support both your anus and your internal reproductive goodies.
You can deliberately move your sacrum relative to your pelvis by using your pelvic floor muscles. Instead of lifting your pelvic floor muscles, an alternative means of activating them is to use them to pull your tailbone forwards, towards your pubic bone. Then you are deliberately nodding your sacrum backwards relative to the pelvis so that the tailbone moves forwards and the top of the sacrum moves back.
Muscles that can be used to accentuate this action include the coccygeus, which we used to use to wag our tails, when we had them, and the piriformis. You can read more about these under mula bandha.
You can think of the lumbar spine as the part of the spinal column that connects your sacrum and pelvis to your ribcage.
It has 5 vertebrae which are acted upon by the erector spinae at the back, and the abdominal muscles and quadratus lumborum to the side and front. This part of the spinal column is also acted on by the psoas major muscle which crosses the joints of the lumbar vertebrae as well as the front of the hip and the respiratory diaphragm.
The joints between the lumbar vertebrae allow the lumbar spine to bend backwards and forwards and from side to side. They also allow very limited twisting.
Note that unlike the thoracic vertebrae which have ribs attached, the lumbar vertebrae don't offer much leverage for twisting. This lack of leverage also means that it can be difficult to leverage the lumbar vertebrae against twisting. For this reason it can be important to learn to feel and control your lumbar spine and related structures. The better you can feel it and control it, the better you can look after it.
The thoracic spine is the part of the spinal column to which the ribs attach. There are 12 thoracic vertebrae.
The joints between these vertebrae do allow twisting, as well as side bending and front and backwards bending. You can find it helpful to think of the ribs as levers. The abs and intercostals attach to these levers to help turn the vertebrae of the thoracic spine relative to each other. They can also act to make the ribcage and thoracic spine stable.
Of all the ribs, the 12th set of ribs are the shortest. And because of this, it may be appropriate that the T12 is designed not to turn relative to L1 (the uppermost lumbar vertebrae) since the bottom most rib offers only a little leverage compared to the other ribs.
There are three "classes" of ribs, floating, false and true ribs.
The bottom two ribs are called floating because they don't have attachments to the sternum.
The false ribs (the next 3 ribs) attach to the costal cartilage the forms the arch of the ribcage that frames the abdominal muscles.
The true ribs (the uppermost 7 ribs) all attach to the sternum
The upper 10 ribs (the true ribs and false ribs) are braced by the transverse processes of the vertebrae that they attach to. These ribs are best suited for using as levers to act on the thoracic spine, particularly in twisting and side bending.
The floating ribs don't attach to the transverse processes and so may not be useful as levers for twisting the thoracic spine. Also recall that the 12th thoracic vertebrae has very limited twistability with respect to the lumbar spine and so the 12th set of ribs may only be useful for leverage in side bending.
Of all the ribs, the 7 true ribs have the least mobility because of their attachment to the sternum. The false ribs have a little bit more mobility and the floating ribs have the most mobility of all.
When used in breathing movements, the lower ribs expand sideways and up. If you arms are by your side and your expand your ribcage your lower ribs would push outwards against your elbows. An easier way to feel this expansion is to wrap a towel around your lower ribs and push outwards against the towel.
The upper ribs tend to expand in a more forwards direction.
Part of this is because of the way that the transverse processes of the thoracic vertebrae get shorter as you move down the spine. This helps to change the lifting angle of the ribs.
Forwards and backwards bending movements of the spinal column can thus be used to accentuate movements of your ribs.
The same is true in side bending. To open up one side of your ribcage bend your thoracic spine to the opposite side. In other words, open one side and close the other, but for more effective bending, focus on actually bending your thoracic spine to the side, while feeling your ribs move in support of this movement.
You may also find that when twisting your thoracic spine you may find that lifting or lowering your ribs can be used to vary the space between your ribs making it easier to deepen your twist.
Because your thoracic spine attaches to the ribs you may find that lifting your ribs makes it easier to bend your thoracic spine backwards. One important sent of muscles in this regard is the Levator Costarum.
These muscles connect the thoracic vertebrae to the ribs and act from the spine to pull upwards on the back of the ribs. Because they are beneath the spinal erectors, you may find it easier to activate them while using your spinal erectors to bend your thoracic spine backwards. However it is possible to activate them with your T-spine bent forwards.
While twisting you may find that activating the levator costalis on one side helps you to deepen your twist.
The cervical spine connects the head to the ribcage and controls the relationship between the two of them.
It has 7 vertebrae and the joints here allow twisting, side bending and front and back bending. Because these vertebrae are slightly wider than then are tall they make side bending the neck challenging.
Personally, when side bending the neck I find it easier to lift the shoulder and the ribs on the side I am leaning away from.
The upper most two cervical vertebrae are special. They aren't shaped like the others because of their special role in directly supporting the underside of the skull.
One important note for developing your ability to feel your cervical spine in its entirety. The base of the skull is about even with the level of our ear holes. Use your ear holes as a guide to visualizing the top of your cervical spine.