This video is to explain to you exactly what happens with sciatica and how it begins anatomically. What's you are looking at right now is a front-view of the lower spine and pelvis area. And what we see here this is what's called the iliac bone, half on each side. This is the pubic bone; this triangular bone here is the Sacrum. This is the last disc this would be typically the L5 S1 disc, the L4, L5 disc.
These are the nerves that are branching off from the spine and you'll see that there is a big nerve down in here and that is what's called the sciatic nerve. The sciatic nerve, as you can see, is made of branches of several other nerves that come off in the lower spine.
The ones that are most note in terms of sciatica are these last two nerves that branch off from the lumbar spine. And you'll see that those two nerves join together and then form part of the sciatic nerve on each side and the reason why these are of the biggest importance, in terms of sciatica, is the vast majority of cases of sciatica are due to problems with the discs. From the front-view we can't really see why this is the problem but that we'll see in just a moment when we turn the spine over.
Now this is the back-views of the spine and again here is the sacrum, triangular bone here, Iliac bones on each side. These by the way, are the femurs, the top of the thigh bone where they attach into the pelvis of the hip joint and here are the sciatic nerves, they are coming out of the pelvis which we saw where they began in the front side of the pelvis a moment ago.
In this view, we can't really see too much as far as where the problems occur with discs because from this side we see just the back joint of the spine and where the nerves are exceeding. But if we turn the spine on next side, we can see that the openings where the nerves come out are right up against where the discs are and if you have a bulge or herniation of that disc, it will push up against that nerve and they can start to create pain and inflammation which then is transmitted all the way down the sciatic nerve which then goes all the way down the leg.
In some cases you're primarily get the sciatica symptoms in the buttock area where the sciatic nerve first forms and comes out of the pelvis and in more severe cases, they will extend to all the way to down to the leg. The other thing that occurs in sciatica is that there is a muscle called the Piriformis and you may in your studies on sciatica have heard something called Piriformis syndrome.
Well Piriformis syndrome is names after a muscle that runs from the sacrum over to the hip, kind of, like this piece of paper. You'll notice that it's in proximity to sciatic nerve right here. What happens is that in some people, it'll be arranged pretty much like this, the muscle will be over the top of the sciatic nerve and the nerve will then go down the leg from there. In other cases, the nerve may actually go on top of the Piriformis and run down the leg that way. And then in some instances, the nerve will actually split the Piriformis muscle and it'll start to go right between the muscle fibers.
In this orientation of the nerve, what will happen in some cases is if you get tightness of the Piriformis muscle, they'll actually squeeze on the sciatic nerve and cause true sciatica that way by actually irritating the sciatic nerve.
In the other arrangement of the Piriformis, the muscle itself can develop knots of contraction that cause a referred pain, very similar to sciatica. It will so run down the leg but it's not a true nerve irritation, it's actually a referred pain.
In either cases, this is usually refer to as Piriformis syndrome and Piriformis syndrome is more of a muscular problem rather than being a direct nerve type of problem. There is a different way of handling this syndrome is disc herniation types of sciatica.
This is to give you a little better idea of what happens with the disc and it's impintment on nerve which then results in sciatica.
This model here is of a normal section of the lumbar spine. And what you'll see here is that we have nice thick front discs that they are well contained and there is lot of space around that nerve for it to move and so that it doesn't get irritated.
This model over here shows a degenerated piece of spine and it also shows a disc herniation that's that red swollen area right there. As you can see that disc herniation is actually pushing up against that nerve and it's actually narrowing the opening for that nerve to come out. And it's this actual mechanical pressure on the nerve plus you'll get swelling and inflammation around that area that also creates pressure and those combined forces create a lot of pressure on that nerve where it where comes off the spine and creates a lot of irritation which then translates into the pain that we call sciatica.
We're going to be talking little bit more about how a normal spine goes from this to this degenerated phase in a later video but for now just realize that it's the disc and/or swelling pressure on the nerve that then irritates it and causes the pain which if this is one of those lower two nerve we've talked about earlier that feeds into the sciatic nerve and you feel the pain in the buttock and/or all the way down the leg.
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