So let's take a closer look
at the units of the vertebra.
So when you look at the thoracic vertebra,
there's a vertebral body anteriorly.
There is the pedicle between the body
and the posterior aspect of the spine.
You have the lamina and this is where
you would have surgery
to remove the lamina in order to
access the spinal cord.
You have the transverse processes
which are located laterally
and this is again where we're palpating
to find any somatic dysfunctions.
And you also have the spinous process
that projects posteriorly.
You have the vertebral foramen
where the spinal cord runs through
and this helps to protect the spinal
cord and the other vertebral notch.
The vertebral notch is actually
formed in between the 2 vertebra
and this is where the nerve root exits.
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.
When we look at the spine and how it articulates with
other spinal segments, there are articular facets.
These articular facets are the articulation
between the spine and usually the one above it.
So there's a superior articular facet which
articulates with the spine right above it.
And so the thoracic spine has superior
articular facets that face convex
so they also face posteriorly,
superiorly and laterally.
The mnemonic for this freedom to remember
is BUL for backwards, up and lateral.
The inferior facet would then
face the opposite way.
The thoracic spine also has costal facets.
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.
So that's why they're demifacets.
They're on each side of the thoracic spine.
So we're talking about vertebral unit, we're
talking about how one segment moves upon another.
And so when we look at the motions available at
the thoracic spine, there are 3 cardinal planes.
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.
In the horizontal plane,
you could have rotation occur
and then in the coronal plane,
you could have side bending occur.
A lot of these motions are coupled in the spine, you
can't have one motion without something else occuring.
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.
The superior segment will move more superior
and anterior compared to the bottom one.
And with extension,
what happens is the facets close.
So again, in the saggital plane, you
could have flexion, extension.
In the transverse, you could have rotation.
And in the coronal, you could have
This is also true not only at the
but also in terms of the motion of the entire
spine, in terms of planes of the motions.
So with my body,
I could flex and extend in the saggital plane.
I could rotate in the transverse plane and I
could side-bend in the frontal coronal plane.
When we look at the articulations of the thoracic spine,
there's articulations of the spine one above and below.
And between these segments,
there is a intervertebral disc.
What the intervertebral disc does is
it helps to cushon,
almost like shock absorbers between
And so the intervertebral disc are
made of 2 different components.
The center of it is the nucleus pulposus,
it tends to be a little bit more elastic.
The anulus fibrosus surrounds it and this tends to be
made of fibrocartilage so it's a little bit more tough.
And what happens with weight bearing
is that when I flex forward,
that nucleus pulposus tends
to be pushed posteriorly.
And then when I extend the spine, that cushon
tends to propel the nucleus pulposus anteriorly.
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.
The facet joints are oriented in
particular way that allows for motion.
It also creates anterior portion of
the spine, has weight bearing properties
and the posterior aspect has
the nerves passing through it.
There's different points of attachment
and it glides.
So if we look at the facets here, in the cervical spine,
the facets tend to be a little bit more transverse.
And so it allows for more rotation.
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.
So based on the orientation of the facets,
this dictates how much motion is
located in each region of the spine.
Taking a look at the different ligaments
connecting the thoracic spine,
we have the anterior longitudinal
There's a posterior longitudinal
ligament and there's different ligaments
in between that helps to stabilize
the thoracic spine.
These ligaments sometimes could be
and could cause different somatic
dysfunctions and asymmetries in the spine.
Taking a look at the muscle layers, you have
the extrinsic, the more superficial layer.
We have the trapezius muscles that spans from the
spine to the scapula and also up to the head.
You have the rhomboid major and minor
which helps to stabilize the scapula.
The levator scapulae from the
scapula up into the cervical spine.
And the latissimus which kinda comes down,
expands and also blends into thoracolumbar fascia.
In the intermediate layer, you could find
intrinsic and extrinsic muscles.
So the erector spinae muscles expand from
the neck all the way down to the sacrum.
And these long muscles attach going from lateral to
medial the intercostalis, the longissimus and spinalis.
A simple mnemonic to remember that
is the "I love sleep" muscles.
The spinalis thoracis is also
considered an intrinsic muscle.
The extrensic muscles on the
intermediate layer include
the serratus posterior superior
and the serratus posterior inferior.
The really deep layer muscles of the thoracic spine
now are more intersegmental and intercostal.
These muscles tend to be restricted
creating more of the segmental dysfunctions,
the type II dysfunctions which
we would talk about in a bit.
So the deep layer intrinsic muscles include
the semispinalis, the multifidus muscles,
rotators: longus and brevis and
the levators: longus and brevis.
So when we want to diagnose for somatic
dysfunctions of the thoracic spine,
we will perform motion testing.
So the motion testing that we perform usually
will consist of being active or passive.
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.
while passive is when the physician
And so there is a usually a further range
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
While you're testing, you're also getting a sense
of how the joint feels and how do the tissues feel.
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.
So the spinal motions, we start with
So our backward bending, this is really
the least motion in thoracic spine.
The vertebrae will approximate posteriorly
and then the disc will expand anteriorly.
Again, it's limited by the articular processes
and the spinous processes, the shingling effect.
Forward bending or flexion,
this is the second least motion.
Again, because of the rib cage, this also limits the
amount of flexion that occurs in the thoracic spine.
Here, when we flex forward, the
interspace between the 2 vertebrae
opens out posteriorly and the
nucleus is displaced posteriorly.
This is where we put the disc
at most vulnerability.
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.
And so if you bend forward and lift,
that puts a tremendous pressure
on the disc causing protrusions
to occur posteriorly.
So again, motion here is limited by different
ligaments and also because of the rib cage.
We could have side bending occur
on the coronal plane.
So side bending is the second greatest
motion of the thoracic spine.
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.
Rotation occurs on the transverse plane.
Rotation is the greatest motion
of the thoracic spine.
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.