Strain Patterns: Overview

00:01 So non-physiologic strain patterns include vertical and lateral strains and also SBS compressions.

00:10 So vertical and lateral strains are non physiologic as they move in a shearing fashion.

00:16 The vertical and lateral strains have the sphenoid and occiput moving in the same direction.

00:23 And so when they move in the same direction, it's not no longer that sort of gear-like fashion that occurs It kinda is due to a trauma and it causes the bones to kinda move against normal motion.

00:36 And so we have two parallel vertical axis where the sphenoid and occiput move in the same direction for lateral strains.

00:46 And lateral strain is named for how the sphenoid moves and what we're really looking at is to be clear, we name it for how the greater wing of the sphenoid moves.

00:59 And so here we have a image, the two blue pipe cleaners are the two vertical axis with the sphenoid and occiput.

01:07 And again, if you try to rotate 2 bones in the same direction, you'll see how it creates a shearing effect there.

01:13 And so for a lateral strain with the greater wing to the left, you see that the sphenoid is displaced a little bit more to the left while the occiput to the right.

01:23 And a lateral strain with the greater wing to the right, the sphenoid is going to shift a little bit more to the right and the greater wing is now more to the right side and the occiput is to the left.

01:36 So what're you gonna feel in a lateral strain with a vault hold So if you start with neutral, if you imagine the sphenoid shifting to the right, your fingers on the greater wing, your pointer fingers on the greater wing are gonna just kinda shift to the right.

01:51 And what's gonna happen with the occiput or the fingers on the occiput is they're gonna shift to the left.

01:55 So what you kinda get is this parallelogram.

01:58 With parallelogram motion your fingers are kinda shifting with your pointer fingers kinda shifting to the right, your pinkie fingers to the left.

02:06 So this would be a lateral strain with the greater wing to the right.

02:11 If we take our hand and now just kinda shift it to the left side, our pointer fingers are now on the greater wing shifting to the left and our fingers on the occiput are now shifting to the right.

02:20 So this would be a lateral strain with the greater wing to the left Vertical strain patterns are non-physiologic cranial patterns.

02:29 What happens on vertical strain patterns is that we're having motion in the same direction about two transverse axes.

02:37 So these are the same axes as normal flexion and extension, however, you're having motion in the same direction.

02:44 This causes a shearing effect at the SBS and what you do is you name the vertical strain pattern for how the sphenoid is moving on the occiput.

02:55 So in a relative position of the basisphenoid, the base of the sphenoid as it is in relation to the occiput where it meets at the SBS.

03:06 So in a superior shear, what you have is the occiput is kind of rotating into extension and the sphenoid is rotating into relative flexion.

03:14 So what happens if my left hand is the sphenoid and my right hand is the occiput.

03:20 Our sphenoid bone is going to rotate anteriorly and our occiput is also going to rotate anteriorly.

03:28 And that causes a shearing effect at the SBS and what you have here is a superior shear because the base of the sphenoid is gonna be higher than the base of the occiput.

03:41 The opposite occurs in inferior shear.

03:43 So our sphenoid is gonna rotate into extension, kinda rotating posteriorly and our occiput is also gonna rotate posteriorly.

03:51 And so in inferior shear, the base of the sphenoid is going to be inferior to the base of the occiput.

04:00 So what is this gonna feel like if you'll have your contact with the vault hold is that you're going to have your hands almost like it's connected to an axle.

04:10 and then in a superior shear, because everything is rotating inferiorly, the fingers are gonna kind of feel like it's all pointing down, 'cause the sphenoid's gonna kinda rotate anteriorly, the occiput's also gonna rotate anteriorly so all your fingers are gonna kinda almost like point down towards the floor.

04:29 So it's counter intuitive, all your fingers are pointing inferiorly but this is the actual motion of a superior shear, cause remember again, we're naming for what's going on at the base of the sphenoid not what's going on with the position of the sphenoid itself.

04:43 So in a superior shear, our fingers are all pointing down towards the feet.

04:48 And in a inferior shear, all the fingers are pointing up towards the head.

04:52 So again, remember our fingers are on the sphenoid, the sphenoid's gonna kinda rotate posteriorly and the occiput is also gonna kinda rotate posteriorly, so that takes our fingers and kinda brings everything up towards the ceiling with the patient lying supine and the sphenoid being on top and the occiput being more by our pinkies by the table.

05:11 So let's apply some of the things that we learned to this question So we have a 15 year old football player, comes in with a history of headache after being hit underneath the chin during a football game 5 days ago.

05:21 You apply a vault hold and you detect the freedom of motion with your fingers rotating in a superior motion towards the apex of the head.

05:28 What is the somatic dysfunction diagnosis? and describe the motion of the sphenoid and occiput in its axis.

05:39 So here, we have inferior shear cranial dysfunction.

05:42 All our fingers are kinda pointing up towards the apex of the head.

05:46 And so, what's happening here is that we have the sphenoid and occiput rotating in the same direction about two transverse axes.

05:52 The sphenoid is going to rotate posteriorly and the occiput is also gonna rotate posteriorly.

05:58 And so that causes all your fingers are gonna feel like it kinda moves superiorly up towards the ceiling.

06:04 This is very common with specific blows, blows underneath the chin, falls and the opposite may occur if you fell backwards and kinda hit the back of your head or sometimes if you sit really hard down on your tail bone, that could cause a pull of the occiput, driving and creating a inferior or superior shear.

06:22 So this shearing patterns are usually secondary due to trauma.

06:30 So here we have a question involving a 2-week old baby, comes to the office brought in by her mom complaining of a misshaped head or plagiocephaly So you apply a frontal occipital hold and you detect the freedom of your hand on the occiput favoring translation to the left and your hand on the frontal bones favoring translation to the right.

06:55 So what is your somatic dysfunction diagnosis? and also describe the movement of the sphenoid and occiput on its axis So here this is a little bit more challenging.

07:08 We've been describing the motion and the movement of the cranial strain patterns with a vault contact.

07:14 Here, we're looking at a contact of frontal-occipital hold and we're describing the occiput translating to the left and your frontal bone translating to the right.

07:26 So what you would feel if you translate that to a vault hold is your fingers kinda, our pointer finger shifting to the right and your pinkie finger shifting to the left.

07:37 So this is a lateral strain with the greater wing to the right.

07:42 And so if we have a lateral strain with the greater wing to the right, our sphenoid and occiput are rotating in the same direction about two transverse axes.

07:50 So it's important to not only understand what you're gonna get a sense of in terms of the cranial bones when you have a vault contact, but also be able to translate that to what's going on with the cranium if you had a fronto-occipital hold also.

08:05 So SBS compression is the last non-physiologic strain pattern Compression at the sphenobasilar synchondrosis pretty much will result in a lack of motion.

08:15 And so what you get a sense of is when you place your hands on a vault hold, is that there's really not a lot of expansion, flexion-extension, doesn't really, not a really good palpable CRI.

08:25 A lot of times this is due to a very severe trauma, head going through a wind shield at fast speeds usually a lot of force really directed towards the midline causing that compression of the spheoid and the occiput resulting in a change in the tissue, resulting in a decrease in motion.

08:43 What my teachers have told me is that it almost feels like when you're palpating the head, it feels like you're palpating a bowling ball.

08:49 It's just very dense, very heavy and really not a lot of appreciable motion in the area.

08:55 So this concludes our review of the cranial strain patterns and hopefully you'll be able to better apply your understanding of the anatomy and physiology of the cranial bones to what's going on with the cranium and be able to diagnose these strain patterns on your patients.