Okay, in this video we're going to discuss and demonstrate cranial strain patterns and what we would feel as the sphenoid and the occiput go through their normal or abnormal motions during each strain pattern. So when we are evaluating cranial strain patterns, we define our strains based on motions of the sphenoid and the occiput. In terms of where we're palpating, we end up palpating greater wings of the sphenoid and the squam of the occiput when we're palpating in ball hold. So in that position, this would be kind of our main position of palpation.
And if we were to then illustrate or represent those motions that we're gonna go over, with just our hands, we would use these greater wings of the sphenoid and the occiput as reference points. and we would create little hands like this that would become our representations of cranial motion. And you'll see a number of those different shadow hands, as they're called, throughout the discussion. So first, in discussing and recognizing what's happening normally during flexion and extension, during normal flexion, the sphenoid rotates anteriorly around a transverse axis that moves to the base of the sphenoid.
and the occiput rotates posteriorly around a transverse axis above the frema magnum. So in flexion, the sphenoid and occiput move like this, and then during extension, that opened motion closes up and might even exaggerate in the opposite direction slightly. So how that manifests then in our hands...
is during flexion our fingers would move farther apart and inferiorly and during extension they would come together and move superiorly. That would be normal motion. Now if we had a strain pattern where we had restricted range of motion in one direction or the other we could have exaggerated flexion or exaggerated extension.
So for exaggerated flexion what we would feel is normal or Exaggerated flexion as is described where the sphenoid and occiput move in kind of exaggerated motion but then during extension they never really fully close up or move into extension. So as a result what we would feel is our fingers opening up during flexion and then during extension they never really come superiorly and feel like they kind of close up and then we enter the flexion phase again and then back. and then enter the flexion phase again. During exaggerated extension, what we would instead feel is a restriction during flexion phase.
So during flexion, we would feel that the cranium doesn't quite open up. We don't feel as much of an open filling in our hands. And then during extension phase, we feel that accentuated with maybe a little bit of extra extension. But the main feature is that...
The bones never really expand and move inferiorly during flexion. So exaggerated flexion and extension are the first of our set of physiologic strain patterns where the SBS and its normal motions are generally intact. Our next physiologic strain pattern would be a side bending rotation.
So now for a side bending rotation, what we essentially have is a restriction in motion where we have a kind of mismatched flexion and extension on either side. So we would end up having, let's say, flexion on one side, this right side, where the sphenoid and occiput move apart and inferiorly, but on the other side we have a restrictive range of motion where it feels almost like that side is extending. How that comes about is we have a restriction that's causing rotation of the sphenoid in one direction, and then we have rotation in the occiput in the opposite direction, and both of those are around vertical axes, one through the body of the sphenoid, and the other one through the foramen magnum.
So as a result, we end up with a rotation in opposite directions. We also end up with a little bit of kind of side bending where we end up with the sphenoid and occiput also rotating around anterior-posterior axes. But because we also have that rotation, it ends up being two anterior-posterior axes, one through foramen magnum kind of anteriorly, and then the other one through the body of the sphenoid as well, kind of in the opposite direction.
So how we would name that is... by which side becomes convex. So in this instance where we have kind of opening and inferior motion on the right side, we would call that a right side bending rotation. And on the opposite would be a left side bending rotation where we would feel that opening on the left side.
Our next physiologic strain pattern would be called a torsion. So if you think about the torsion terminology, When you are describing sacrum dysfunction, the way we describe torsion is essentially a twisting motion where you have the sacrum rotating in one direction and then L5 rotating in the opposite direction. In this instance, it's going to be very similar where the occiput rotates in one direction and then the sphenoid rotates in the opposite direction.
So both of the bones are going to be rotating in opposite directions. around, in this instance, a single anterior-posterior axis that goes through the frame of magnum and then through the body of the sphenoid. Now, how we're going to name those dysfunctions will be defined by which greater wing of the sphenoid we feel moves more superiorly.
So if the bones move in this direction, we would feel kind of a twisting in our hands, and we would call that right torsion. In the opposite direction we would feel the left greater wing of this phenoid move superiorly and we call that a left torsion. And the reason this is kind of still a physiologic pattern is the SBS motion is still intact where it hasn't really sheared apart and we kind of have a twisting motion around that around that SBS. Now moving on to The non-physiologic or pathologic strain patterns, essentially for each of these we have abnormal motions at the sphenobasilar symphysis. So for each of these pathologic dysfunctions, we essentially have an abnormal motion at the sphenobasilar symphysis, which are usually shearing patterns or compressive kinds of patterns.
So the question we can ask ourselves, of course, is which directions can... the sphenobasilar symphysis shear in. So certainly they can shear laterally, and then they can shear vertically, this way and this way.
So first discussing a lateral strain pattern or a lateral shearing force at the SBS. Essentially what's happening is the sphenoid and the occiput are going to rotate in the same direction around vertical axes. And again, our vertical axes are through the frame of magnum and through the body of the sphenoid. So they're rotating in the same direction around that vertical axis. And as a result, are causing shearing force at the SBS.
Now, there's a few different ways that it's described in terms of how you're going to palpate it in your hands. One description. focuses on more of the shearing force where if we're defining and kind of illustrating by our shearing force we could illustrate that by showing our hands kind of shearing laterally this way and this would create a parallelogram in that direction where we would see a right lateral strain where the sphenobasilar symphysis has shifted to the right and we end up with a parallelogram towards the right side Another description focuses more on the rotatory force of the strain pattern, where if we're thinking of our two vertical axes, and then we're considering the rotation around those axes, the sphenoid would rotate to the left, which would bring the greater wing of the sphenoid anterior and medial, and then the occiput would rotate also to the left, where the squama of the occiput swings laterally and anteriorly.
As a result, That would feel more like a parallelogram that is shifting to The left. As a unifying descriptor of how we're going to define our lateral strains, we're going to be focusing on what the base of the sphenoid is doing in each pattern. So as we're focusing on rotatory force or the rotatory vectors of abnormal motion, we're going to consider this motion with a parallelogram.
forming this way as a right lateral strain as the base of the sphenoid shifts to the right during that phase of motion. In an opposite direction we would find a left lateral strain where they're rotating in opposite directions and our parallelogram we'd feel move to the right as our occiput swings laterally. Okay our next pathologic strain pattern that we're going to talk about is a vertical strain. So in this instance, similar to our lateral strains, the sphenoid and occiput are going to rotate in the same direction, but this time around transverse axes.
So first, we can have a superior vertical strain where both the sphenoid and occiput rotate anteriorly around transverse axes, and that transverse axis is... through the base of the sphenoid and then above the foramen magnum. And we're naming this a superior vertical strain because of the direction that the base of the sphenoid moves.
It moves superiorly relative to the occiput. And in the opposite direction, it would be an inferior vertical strain. Now, what would that feel like?
What it would feel like due to kind of the motions of the greater wings of the sphenoid and the occiput is that it would feel like the sphenoid is moving is during a superior vertical strain we would feel as if our hands are going to kind of fall forward, which we would represent by kind of a shifting of our fingers forward and our wrists kind of coming up. So we can kind of think of our wrists moving superiorly as a superior vertical strain. In the opposite direction for an inferior vertical strain where the The base of the sphenoid is moving inferiorly because of that direction of the sphenoid and occiput.
We could think of our hands coming this way. So this would be representative of an inferior vertical strain with our wrists kind of representing the SBS as it moves inferiorly. The last pathologic motion pattern is a compression, which is essentially defined as restricted motion. at the sphenobasilosynthesis in all directions of motion. So during both phases of flexion and extension, we essentially have very limited or no motion.
So in flexion, there's not much motion. Extension, there's not much motion. Very, very small motions are palpated.
And what ends up happening is we end up feeling that as kind of a stagnant cranium that feels very heavy, often described as a bowling ball feeling, which is kind of... A very typical way of describing that feeling. Essentially we have no motion in any of the directions. And that will conclude our discussion and illustration of cranial strain patterns.