Cranial Motions at the SBS

00:01 So different strain patterns exist at the SBS.

00:04 So what we're looking at here are physiologic and non physiologic strain patterns.

00:09 So physiologic strain patterns are strain patterns that usually exist and is not due to trauma.

00:16 So, flexion and extension is normal motion at the SBS.

00:21 Your sphenoid and your occiput will undergo flexion and extension because they move in about two transverse axis in a gear like fashion.

00:31 And when you move in opposite directions in the gear like fashion, that tends to be more physiologic.

00:36 Torsions also are considered physiologic and side bending rotation are physiologic strain patterns.

00:43 Your non-physiologic strain patterns tend to be more due to trauma.

00:48 These strain patterns no longer move in a gear-like fashion.

00:53 Vertical shears cause a shearing.

00:56 All these vertical and lateral shears both create a shearing pattern along the SBS where the occiput and sphenoid are moving in the same direction and thus no longer in a gear-like fashion and SBS compression as it sounds is really the sphenoid and occiput really being pushed together and having a loss of normal motion in the region.

01:20 So cranial flexion and extension occurs about two transverse axes.

01:26 The sphenoid and occiput rotate in opposite directions.

01:30 So in cranial flexion or also called inhalation, the sphenoid's gonna rotate anteriorly and the occiput's gonna rotate posteriorly.

01:38 This is going to cause the head to have a increased transverse diameter and decreased AP and vertical diameter.

01:47 What happens is, with the midline bones when you have flexion, the paired bones like the temporal bones will externally rotate.

01:58 In cranial extension or exhalation phase, the sphenoid's gonna rotate posteriorly and the occiput is also gonna rotate anteriorly.

02:06 This is gonna cause the head to kinda decrease it's transverse size diameter and kinda increase it's anterior-posterior and vertical diameter.

02:14 Here also the paired bones are going to internally rotate.

02:20 A good way to picture flexion and extension head is to use our Sesame street characters that we might be familiar with.

02:28 And so here we have Ernie, Ernie displays more of a flexion head.

02:32 His head is a little bit more oval, shaped with a little bit more wider and shorter head.

02:39 And so, again in inhalation phase or flexion phase, the sphenoid and occiput are in flexion.

02:45 The paired bones will externally rotate.

02:48 And so, this is gonna cause more of a broaden transverse diameter, a little bit more narrow anterior-posterior and vertical diameter, similar to what you see with Ernie here.

03:00 Bert displays more of an extension head.

03:02 So Bert's head is a little bit more oval but more in a vertical direction, a little bit more taller, a little bit more narrow.

03:10 So the exhalation phase is more of a Bert head.

03:13 So you have extension of the sphenoid and occiput and then internal rotation of the paired bones causing that narrow, increase in AP or anterior-posterior and vertical diameter.

03:27 So again, flexion and extension occur at the sphenoid and occiput.

03:32 If you have an exaggeration of flexion or exaggeration of extension, then that is the name of that cranial dysfunction.

03:42 Here is an image of what's occuring at the sphenoid and occiput.

03:47 So again, the middle is neutral wherein our starting point and then flexion you could see about two transverse axes, sphenoid and occiput rotate in opposite directions and then in extension the sphenoid and occiput rotate in opposite directions with the sphenoid kind of rotating posteriorly and the occiput rotating anteriorly.

04:07 So we utilize the vault hold in order to diagnose what's going on with the cranial base.

04:12 Remember that the orientation changes here a little bit.

04:14 You're gonna have the sphenoid more superior to the occiput with the patient lying supine on the table.

04:21 And so, with our vault hold, our pointer finger's really gonna contact the sphenoid by the greater wing and our pinkie finger is gonna contact the occiput with our 3rd and 4th fingers over the parietals and temporals.

04:33 And so if we understand the potential change in shape of the cranium, we could kind of anticipate what we're gonna get a sense of when we're palpating the head in the vault hold.

04:43 And so, this image is of cranial neutral, we have our hands on the vault hold, comfortably resting and sensing what's going on with the head.

04:54 Now with cranial flexion, remember that the transverse diameter is gonna increase.

04:59 So if my fingers are on the sphenoid and the occiput and I have increase in AP diameter, my fingers are gonna spread out a little bit.

05:07 And then because the vertical diameter is gonna decrease, I'm gonna feel my fingers kinda shift a little bit more inferiorly towards the feet of the patient.

05:17 So what you're gonna feel in cranial flexion from a vault hold perspective is your fingers' gonna spread out a little bit maybe expand a little bit to get a little bit wider and move a little bit more down towards the feet.

05:30 The opposite's gonna occur in cranial extension.

05:32 So remember in cranial extension, our transverse diameter is gonna decrease so our fingers are gonna kinda come closer together and then our vertical diameter is gonna increase.

05:41 So our fingers are gonna kinda move superiorly up towards the top of the head a little bit.

05:45 So remember what would you kind of feel if you had flexion and extension is you're gonna get a sense of a Bert and Ernie head.

05:53 So you're gonna feel your flexion phase and then your extension phase.

05:57 This is greatly exaggerating what's going on at the cranium but for you to visualize what you might feel in the vault hold, our fingers are gonna spread out and move out laterally for flexion and then our fingers are gonna come close together, move superiorly up towards the apex of the head in extension.

06:13 Another strain pattern that you could feel is the sidebending rotation strain pattern.

06:18 Again this is a physiologic strain pattern, our motion here is occuring about two vertical axes and one AP axis.

06:27 So first, the sphenoid and occiput are going to rotate on opposite directions on two vertical axes.

06:32 That's gonna cause a side bending of the sphenoid on the occiput.

06:35 So one side is gonna be more concave and one side is gonna be more convex or wide.

06:40 The side of the convexity is going to be the side that the sphenoid and occiput is gonna rotate about a AP axis.

06:48 So what we're going to get is a side bending on two vertical axes and then a rotation about the AP axis.

06:57 So the sphenoid and occiput are still rotating in opposite directions on the vertical axis but in the same direction in the AP axis.

07:06 We're gonna name the side bending rotation on the side of that convexity or the side of that wide side, the side that the rotation is occuring towards on that AP axis.

07:17 When you have a side bending rotation dysfunction, you're going to actually see some asymmetries that may occur in the face.

07:25 And so, here are some different landmarks on the face that you could get a sense of where you might see asymmetry based on the side of convexity and the side of concavity.

07:36 So here is an image demonstrating the motion and movement.

07:38 We have two vertical axes and so you have the side bending that occurs at the cranial base at the SBS.

07:46 In the middle you have neutral and on the right here you have the rotation occuring about the AP axis.

07:53 So, this is a right side bending rotation where more convex on the right side and then we rotate both the sphenoid and occiput to the right.

08:02 So here is a image of what you're gonna feel with your hands.

08:06 So remember, if we are side bending and we have a side that is a little bit more convex, what we're gonna get a sense of is our fingers are gonna spread apart a little bit more on that side.

08:17 So let's take right side bending rotation for example.

08:20 So if I have a right side bending rotation and I have my sphenoid and occiput rotate on two vertical axes, that's gonna create a gapping where my sphenoid and occiput is going to spread a little bit more on the right side.

08:32 So my fingers are gonna spread out on the right side, whereas my fingers on the left hand are gonna come a little bit closer together.

08:39 So that's gonna account for the side bending.

08:41 Now we're gonna have a rotation on the AP axis.

08:44 So remember again the orientation in a vault hold is that the sphenoid is on top, the occiput's on the bottom.

08:50 So if I have a rotation to the right, that's gonna bring my entire hand down towards the feet of the patient on the right side.

08:58 Whereas on the left side, my hands are gonna come closer together and then up towards the vertex of the head.

09:04 So in a right sidebening rotation, our fingers are gonna spread on the right side and go down towards the feet.

09:10 Where on the left side, my fingers are gonna come close together and up towards the head.

09:14 The opposite's gonna occur in a left sidebending rotation.

09:17 So in the left side bending rotation on the vault hold, our fingers on the left side are gonna spread out and rotate towards the feet and our fingers on the right side are gonna come closer together and come up towards the head.

09:27 Based on what's going on with the SBS and how the vault is accommodating for that.

09:32 Cranial strain patterns include torsions.

09:35 So torsions are a physiologic strain pattern.

09:38 The sphenoid and occiput are rotating in opposite directions about a AP axis.

09:44 So there is one axis, one single AP axis, kinda from the nasion from to opisthion And what happens is you're going to have the torsion of the sphenoid and occiput and what you do is you name the torsion for the side of the greater wing of the sphenoid.

10:00 So what you're gonna see is one side of the sphenoid is gonna be higher than the other.

10:05 And so, if you are rotating the sphenoid clockwise, what you're going to get is a left higher wing and so that will be a left torsion.

10:15 If you rotate the sphenoid counter-clockwise, that's going to be a right greater wing that's higher and that's going to be a right torsion.

10:24 Here's a image of that a little bit more.

10:26 You could see the pipe cleaner there, it's the AP axis.

10:30 And so you have rotation of the sphenoid clockwise creating a left torsion and the rotation of the sphenoid counterclockwise creating a right torsion.

10:44 So looking at what we're gonna get a sense of, if we have a torsion and we're using the vault hold to palpate the cranium.

10:51 So again, if we're palpating the cranium and we're getting a sense of a torsion, what you're gonna feel is that the greater wing of the sphenoid is going to rotate and the hands are gonna rotate in opposite directions.

11:03 And so, our right hand is gonna kinda rotate superiorly in a right torsion and the left hand is gonna kind of rotate inferiorly and the opposite's gonna occur in the left torsion.

11:15 Our left hand is gonna rotate superiorly whereas the right hand is gonna kinda rotate inferiorly.

11:20 The contact on the greater wing is gonna feel like it moves more superiorly and the rest of the fingers are also gonna follow.

11:29 So let's do some practice question applying the knowledge that we just reviewed.

11:33 We have a 20 year old female with a history of migraine, comes in with a headache for the past 4 hours.

11:38 When you're applying a vault hold, you note increased fullness on the right side of her head.

11:42 You note that your fingers on the right hand favor inferior motion towards the feet and the fingers on your left hand favors superior motion towards the apex of her head.

11:51 What is the cranial somatic dysfunction here? and describe the motion of the sphenoid and occiput on it's axis.

11:57 So, it's important based on your findings of the vault hold to be able to make a diagnosis.

12:03 But also, once you make the diagnosis to be able to explain what is actually happening biomechanically at the sphenoid and the occiput.

12:14 So here, the vault hold is describing a right side bending rotation.

12:18 You have that extra fullness on the right side, your fingers are spreading out and kinda moving more inferior towards the feet on the right and the fingers on the left are coming more together and coming up towards the apex of the head.

12:31 So we have a right sidebending rotation which is a rotation of the sphenoid and occiput in opposite direction on two vertical axes and then a rotation on the AP axis.

12:41 In this case, because it's a right side bending rotation, it's gonna rotate inferiorly to the right.