Osteology, Articulations and Motion Testing

00:01 So let's take a closer look at the units of the vertebra.

00:06 So when you look at the thoracic vertebra, there's a vertebral body anteriorly.

00:10 There is the pedicle between the body and the posterior aspect of the spine.

00:15 You have the lamina and this is where you would have surgery to remove the lamina in order to access the spinal cord.

00:23 You have the transverse processes which are located laterally and this is again where we're palpating to find any somatic dysfunctions.

00:30 And you also have the spinous process that projects posteriorly.

00:33 You have the vertebral foramen where the spinal cord runs through and this helps to protect the spinal cord and the other vertebral notch.

00:39 The vertebral notch is actually formed in between the 2 vertebra and this is where the nerve root exits.

00:44 This is the key area to look especially for patients that may have potential disc herniations because the disc usually herniates posterolaterally that could usually compress on the nerve root.

00:55 When we look at the spine and how it articulates with other spinal segments, there are articular facets.

01:03 These articular facets are the articulation between the spine and usually the one above it.

01:09 So there's a superior articular facet which articulates with the spine right above it.

01:14 And so the thoracic spine has superior articular facets that face convex so they also face posteriorly, superiorly and laterally.

01:24 The mnemonic for this freedom to remember is BUL for backwards, up and lateral.

01:28 The inferior facet would then face the opposite way.

01:32 The thoracic spine also has costal facets.

01:34 These costal facets are demifacets because each rib are actually common attached to the thoracic spine and it will attach at the level of and the one above it.

01:44 So that's why they're demifacets.

01:46 They're on each side of the thoracic spine.

01:50 So we're talking about vertebral unit, we're talking about how one segment moves upon another.

01:55 And so when we look at the motions available at the thoracic spine, there are 3 cardinal planes.

02:03 So the planes of motion include the sagittal plane which is straight anterior-posterior and in this plane of motion, you could have flexion and extension occur.

02:13 In the horizontal plane, you could have rotation occur and then in the coronal plane, you could have side bending occur.

02:23 A lot of these motions are coupled in the spine, you can't have one motion without something else occuring.

02:29 When we look at the facets, when we flex the segment, what you have is the facets open up between the top and the bottom.

02:39 The superior segment will move more superior and anterior compared to the bottom one.

02:45 And with extension, what happens is the facets close.

02:49 So again, in the saggital plane, you could have flexion, extension.

02:53 In the transverse, you could have rotation.

02:56 And in the coronal, you could have side bending.

02:59 This is also true not only at the vertebral unit but also in terms of the motion of the entire spine, in terms of planes of the motions.

03:07 So with my body, I could flex and extend in the saggital plane.

03:11 I could rotate in the transverse plane and I could side-bend in the frontal coronal plane.

03:17 When we look at the articulations of the thoracic spine, there's articulations of the spine one above and below.

03:25 And between these segments, there is a intervertebral disc.

03:28 What the intervertebral disc does is it helps to cushon, almost like shock absorbers between the bones.

03:33 And so the intervertebral disc are made of 2 different components.

03:36 The center of it is the nucleus pulposus, it tends to be a little bit more elastic.

03:40 The anulus fibrosus surrounds it and this tends to be made of fibrocartilage so it's a little bit more tough.

03:46 And what happens with weight bearing is that when I flex forward, that nucleus pulposus tends to be pushed posteriorly.

03:53 And then when I extend the spine, that cushon tends to propel the nucleus pulposus anteriorly.

04:00 You have facet joints, we talk about the superior and inferior facet joints and this helps permit gliding between the thoracic segments and then you have the thoracic segments as it articulates with the rib cage through those demifacets.

04:15 The facet joints are oriented in particular way that allows for motion.

04:19 It also creates anterior portion of the spine, has weight bearing properties and the posterior aspect has the nerves passing through it.

04:29 There's different points of attachment and it glides.

04:33 So if we look at the facets here, in the cervical spine, the facets tend to be a little bit more transverse.

04:40 And so it allows for more rotation.

04:42 And as we move further and further down along the spine, when we reach the lumbar spine, the superior facets tend to be more medial so then this allows for more motion in the saggital plane which is the primary motion of the lumbar spine being flexion and extension.

04:58 So based on the orientation of the facets, this dictates how much motion is located in each region of the spine.

05:05 Taking a look at the different ligaments connecting the thoracic spine, we have the anterior longitudinal ligament.

05:13 There's a posterior longitudinal ligament and there's different ligaments in between that helps to stabilize the thoracic spine.

05:20 These ligaments sometimes could be restricted and could cause different somatic dysfunctions and asymmetries in the spine.

05:29 Taking a look at the muscle layers, you have the extrinsic, the more superficial layer.

05:33 We have the trapezius muscles that spans from the spine to the scapula and also up to the head.

05:40 You have the rhomboid major and minor which helps to stabilize the scapula.

05:44 The levator scapulae from the scapula up into the cervical spine.

05:50 And the latissimus which kinda comes down, expands and also blends into thoracolumbar fascia.

05:56 In the intermediate layer, you could find intrinsic and extrinsic muscles.

06:00 So the erector spinae muscles expand from the neck all the way down to the sacrum.

06:04 And these long muscles attach going from lateral to medial the intercostalis, the longissimus and spinalis.

06:13 A simple mnemonic to remember that is the "I love sleep" muscles.

06:18 The spinalis thoracis is also considered an intrinsic muscle.

06:22 The extrensic muscles on the intermediate layer include the serratus posterior superior and the serratus posterior inferior.

06:28 The really deep layer muscles of the thoracic spine now are more intersegmental and intercostal.

06:36 These muscles tend to be restricted creating more of the segmental dysfunctions, the type II dysfunctions which we would talk about in a bit.

06:43 So the deep layer intrinsic muscles include the semispinalis, the multifidus muscles, rotators: longus and brevis and the levators: longus and brevis.

06:58 So when we want to diagnose for somatic dysfunctions of the thoracic spine, we will perform motion testing.

07:04 So the motion testing that we perform usually will consist of being active or passive.

07:11 Active meaning the patient will perform it, so you wanna instruct your patient to please flex forward or extend or to side bend or to rotate.

07:19 while passive is when the physician does it.

07:21 And so there is a usually a further range of motion that you could find with passive range of motion testing than active because the patient should be relaxed, the muscles should be relaxed, we should be able to move it a little bit further.

07:34 While you're testing, you're also getting a sense of how the joint feels and how do the tissues feel.

07:38 You could get a sense of the resistance as you're performing passive range of motion, whether or not it's easy to move the joint or a little bit more challenging to move the joint.

07:46 So the spinal motions, we start with extension.

07:51 So our backward bending, this is really the least motion in thoracic spine.

07:55 The vertebrae will approximate posteriorly and then the disc will expand anteriorly.

08:02 Again, it's limited by the articular processes and the spinous processes, the shingling effect.

08:09 Forward bending or flexion, this is the second least motion.

08:13 Again, because of the rib cage, this also limits the amount of flexion that occurs in the thoracic spine.

08:20 Here, when we flex forward, the interspace between the 2 vertebrae opens out posteriorly and the nucleus is displaced posteriorly.

08:27 This is where we put the disc at most vulnerability.

08:31 So when you think about herniated disc or disc herniations, a lot of times these will occur posterolaterally 'cause that's where the angle is most weak.

08:40 And so if you bend forward and lift, that puts a tremendous pressure on the disc causing protrusions to occur posteriorly.

08:49 So again, motion here is limited by different ligaments and also because of the rib cage.

08:55 We could have side bending occur on the coronal plane.

08:58 So side bending is the second greatest motion of the thoracic spine.

09:01 Here, we have the articular facets are going to slide relative to each other and so the articular processes when you are sliding is limited by the different ligaments on laterally and a little bit by the rib cage also.

09:18 Rotation occurs on the transverse plane.

09:20 Rotation is the greatest motion of the thoracic spine.

09:23 And again, the orientation of the superior articular facets of the thoracic spine allows for the greatest motion of rotation and really it's limited by different ligaments and also the muscles attached to the spine.