Segmental Vertebral Specification – Vertebral Column

00:01 Now that we understand the basic structural blueprint of a typical vertebra, we can utilize that blueprint to understand segmental vertebral specification.

00:12 So, as we move from one segment to another cervical, thoracic, to lumbar, sacral.

00:18 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.

00:34 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.

00:46 And again, these are unique to the cervical vertebrae and these are referred to as uncinate processes.

00:55 We can also see transverse processes.

00:59 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 foramine.

01:15 So, transverse foramina are signature or hallmark features of the transverse processes of the cervical segments.

01:25 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.

01:41 And this projection here is the posterior tubercle.

01:46 And then if we look right in through here, we have an anterior tubercle as well.

01:54 This particular slide is demonstrating the first of two unique cervical vertebrae.

02:02 And this one happens to be C1, also known as the Atlas.

02:07 We have two images here, so the first thing I wanna do is kinda orient you to the views that are shown here. This is an inferior view. This is the anterior aspect of C1, and then this is the posterior aspect of C1.

02:27 This is a superior view of C1.

02:32 And again, this would be the anterior portion, and this would be the posterior portion.

02:40 Now, let's focus on the unique or signature features here of C1.

02:46 And the first thing you're gonna note is that C1 is a ringlike structure.

02:51 And as you move about the ring, you will not see a body.

02:56 C1 does not have a body, so that makes it extremely unique.

03:01 If you look out here laterally, you see the superior articular processes that C1 has.

03:10 In a superior view, these articulate with the occipital bone of the skull.

03:16 And if you look inferiorly, you see articular processes as well and these will articulate with the superior articular processes of the vertebra below.

03:29 In that case that would be C2, also known as the Axis.

03:35 These processes 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.

03:50 Connecting the lateral masses together are two arches.

03:54 So, here is your anterior arch and then here is your posterior arch.

04:01 And the same thing where we have the anterior arch, and then here is your posterior arch.

04:09 Associated with each arch is its respective tubercle, so if we take a look at the anterior arch, we see the anterior tubercle here.

04:20 If we look at the posterior arch, we see the posterior tubercle.

04:26 And we can also see what is a signature feature of all cervical vertebrae.

04:32 If we take a look at the transverse process here and over here, we can more clearly see the transverse foramina.

04:43 The transverse foramina will transmit the vertebral artery and vertebral vein.

04:50 The second very unique vertebral component of the cervical segment is a C2.

05:01 C2 is known as the Axis. So, the Atlas can rotate or pivot about C2.

05:09 The signature feature of C2 that will give it away so it's very easy to recognize, is a single tooth like; a process called the dense or the odontoid process.

05:25 Odontoid in reference to a tooth like structure or eminence.

05:31 The body is shown in this area, so we do have a body.

05:35 We also have pedicles that will connect the body to laminae.

05:40 And so, here we see the two laminae, and then the laminae that unite posteriorly, like in the midline, and we can see the spinous process that is now associated with C2 and it - as seen in the previous slide is bifid.

05:57 And again, transverse processes each housing its own transverse foramen.

06:05 Now that we understand the segmental specification of the cervical vertebrae, our next stop along the vertebral column is we move distally or inferiorly is that of the thoracic vertebrae.

06:24 Signature feature unless there's an anatomic variation, but a signature feature here of our thoracic vertebrae is gonna be the presence of facets for the ribs.

06:39 And so if we take a look here, we do see a rib.

06:43 And again, if you don't have a variation, ribs are gonna only articulate with thoracic segments of our vertebral column.

06:54 This portion of the rib is articulating with a facet on the vertebral body.

07:00 And then on the opposite side with be rib removed, we see where that point of articulation would be.

07:08 Laterally, we have a clear view of how ribs will articulate with the vertebral bodies.

07:16 Typically, ribs will articulate with two adjacent vertebral bodies with the head at the rib doing that point of articulation.

07:30 Another point of articulation is seen here where a portion of the rib articulates with a facet that is found on the transverse process.

07:42 Some other features associated with thoracic vertebrae is at the vertebral foramen is smaller than in the cervical area.

07:53 And then vertebral bodies will become larger as you progressively move inferiorly along their vertebral column.

08:04 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.