Now that we understand the basic structural
blueprint of a typical vertebra, we can utilize
that blueprint to understand segmental vertebral
So, as we move from one segment to another,
cervical to thoracic to lumbar and sacral,
what are the modifications that are made to
this basic structural blueprint?
And let’s begin with the cervical segment
by looking at the modifications that are placed
upon the cervical vertebrae. The first is
that if we look at the vertebral bodies of
several of these cervical vertebrae, we will
see that they have these superiorly-oriented
processes. And again, these are unique to
the cervical vertebrae and these are referred
to as uncinate processes. We can also see
transverse processes. They alone are not unique
to the cervical segment. But, here, if we
look up right in through here, we can see
an opening within the transverse process that’s
referred to as the transverse foramen. So,
transverse foramina are signature or hallmark
features of the transverse processes of the
Lastly, we have some tubercles that are associated
with the transverse processes. And those are
best seen at this level, the transverse portion
of the cervical vertebra. And this projection
here is the posterior tubercle. And then if
we look right in through here, we have an
anterior tubercle as well.
This particular slide is demonstrating the
first of two unique cervical vertebrae. And
this one happens to be C1, also known as the
atlas. We have two images here. So, the first
thing I want to do is kind of orient you to
the views that are shown here.
This is a superior view of C1. This is the
anterior aspect of C1. And then this is the
posterior aspect of C1 in a superior view.
The image below is an inferior view. And again,
this would be the anterior portion and this
would be the posterior portion.
Now, let’s focus on the unique or signature
features here of C1. And the first thing you’re
going to note is that C1 is a ring-like structure.
And as you move about the ring, you will not
see a body. C1 does not have a body. So, that
makes it extremely unique.
If you look out here laterally, you see the
superior articular processes that C1 has.
In the superior view, these articulate with
the occipital bone of the skull. And if you
look inferiorly, you see articular processes
as well and these will articulate with the
superior articular processes of the vertebra
below. In that case, that would be C2, also
known as the axis.
These processes, the superior ones and the
inferior ones, are associated with lateral
masses. So, we see the lateral mass on this
side and we see the lateral mass on the opposite
side of C1. Connecting the lateral masses
together are two arches. So, here is your
anterior arch and then here is your posterior
arch. And the same thing in the inferior view
where we have the anterior arch and then here’s
your posterior arch.
Associated with each arch is its respective
tubercle. So, if we take a look at the anterior
arch, we see the anterior tubercle here. If
we look at the posterior arch, we see the
posterior tubercle. And we can also see what
is the signature feature of all cervical vertebrae,
if we take a look at the transverse process
here and over here, we can, more clearly,
see the transverse foramina. The transverse
foramina will transmit the vertebral artery
and vertebral vein.
The second very unique vertebral component
of the cervical segment is C2. C2 is known
as the axis. So, the atlas can rotate or pivot
about C2. The signature feature of C2 that
will give it away, so it’s very easy to recognize
is this single tooth-like process, called the
dens or the odontoid process, odontoid in
reference to a tooth-like structure or eminence.
The body is shown in this area. So, we do
have a body. We also have pedicles that will
connect the body to laminae. So, here we see
the two laminae. And then the laminae unite
posteriorly in the midline and we can see
the spinous process that is now associated
with C2, and as seen in a previous slide,
is bifid. And again, transverse processes,
each housing its own transverse foramen.
Now that we understand the segmental specification
of the cervical vertebrae, our next stop along
the vertebral column, as we move distally
or inferiorly, is that of the thoracic vertebrae.
Signature feature, unless there’s an anatomic
variation, but the signature feature here
of our thoracic vertebrae is going to be the
presence of facets for the ribs.
And so, if we take a look here, we do see
a rib and again, if you don’t have a variation,
ribs are going to only articulate with thoracic
segments of our vertebral column. This portion
of the rib is articulating with a facet on
the vertebral body. And then on the opposite
side with the rib removed, we see where that
point of articulation would be. Laterally,
we have a clear view of how ribs will articulate
with the vertebral bodies.
Typically, ribs will articulate with two adjacent
vertebral bodies, with the head of the rib
doing that point of articulation. Another
point of articulation is seen here where a
portion of the rib articulates with a facet
that is found on the transverse process.
Some other features associated with thoracic
vertebrae is that the vertebral foramen is
smaller than in the cervical area. And then
vertebral bodies will become larger as you
progressively move inferiorly along the vertebral
column. And then if you take a look here,
spinous processes tend to be much longer than
the other vertebral segments and they will
slope or slant inferiorly.
Next, let’s take a look at the segmental
vertebral specification for our lumbar vertebrae.