Anatomy of the Vertebral Column

00:01 Now we're going to start talking about the anatomy of the back.

00:05 We're going to start by talking about the back bone or what we actually call the vertebral column.

00:12 The vertebral column is collection of bones that we group according to their location.

00:18 We have the cervical area which has seven portions.

00:23 We have the thoracic area, which has 12.

00:28 And we have the lumbar that has five.

00:31 By the time we get to the inferior most portion, we have the sacrum, which is actually a single bone formed by the fusion of five different bones.

00:41 And then the tiniest bit at the end, also called the tailbone, is the coccyx formed by between three and five fused bones.

00:51 If we look at the vertebral column from an anterior view, the first thing we'll see is a typical what we say vertebra.

01:00 And each vertebra is separated from the adjacent one by an intervertebral disc.

01:08 And this is going to be a description of a what we call basic vertebra.

01:12 Later on, we'll talk about regional variations that make for example, the cervical vertebra slightly different from the lumbar vertebra.

01:20 But for right now, we'll start with a superior view of the basic features of a vertebra.

01:27 In anteriorly, the majority of the vertebra overall is made up of the body.

01:34 Posteriorly, we have a little bit more complicated structure here and we call this collectively the vertebral arch.

01:42 We see that laterally we have these processes called transverse processes.

01:49 And then although it's hard to tell in a superior view, but these are pointing superiorly as the superior articular facets and articular means referring to a joints.

01:59 We know that that's going to be participating in a joint.

02:04 And then posteriorly, we have a single midline structure called the spinous process.

02:10 The spinous process is connected to the rest of the vertebral arch by lamina.

02:17 And the vertebral arch connects to the body by short pedicles.

02:23 Let's look at a basic vertebra from an anterior point of view.

02:28 From this point of view, mostly what we see is the vertebral body.

02:33 But laterally we can see a bit of the transverse processes.

02:36 Just a little bit of the superior and inferior articular facets on either side.

02:45 In a lateral view, we can still see a lot of the vertebral body.

02:49 A little bit of the transverse process.

02:51 And from this view, we can really see the superior and inferior articular facets as well as the spinous process.

03:00 From a posterior point of view, now the body is kind of out of our viewpoint here we can barely see it.

03:06 But we can still see the transverse processes, the superior and inferior articular facets.

03:12 And absolutely the spinous process.

03:17 Let's look at a cross section of an intervertebral disk now.

03:21 There intervertebral disk basically has two components, a tough outer portion called the annulus fibrosus, and a softer squishier inner portion called the nucleus pulposus.

03:36 And together these intervertebral discs form fibrocartilaginous joints.

03:42 These aren't the highly movable joints are used to in other parts of the body.

03:46 They're really there to provide strength and support and only a limited degree of movement.

03:52 Because after all, we do have the spinal cord running through the vertebral column so we don't want to have too much movement.

04:01 Now over time, the intervertebral disc can become degenerated.

04:06 And that can lead to all sorts of problems.

04:10 For example, if the annulus fibrosis becomes weak, it may bulge outward from its normal area and cause what's called a bulging disc.

04:20 If it gets worn down to the point that there's a defect or crack in the annulus fibrosis, then the nucleus pulposus can squeeze out through that opening causing a herniated disc because it's herniating through an opening in the annulus fibrosis.

04:38 And over time, the disc can basically dehydrate and get thin.

04:43 And when it does that the adjacent vertebral bodies can rub up against each other and cause osteophyte formation in a form of osteoarthritis.

04:55 So let's look at a superior view of what happens with a herniated disc.

05:01 So with a normal disc, the spinal nerve has a free pathway out beyond the vertebral column.

05:09 With a herniated disc that nucleus pulposus can squeeze out and impinge upon the nerve root at that area.

05:19 And unfortunately what that means is there will be pain and numbness in any of the areas that are innervated by that compressed nerve.