Spine - Features of a Vertebra

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Transcription

Okay so this is a tutorial on the individual features the vertebra, so in this tutorial ill just talk you through the different parts of the vertebra, all the different processes, facets, and all that, so you'll get an idea of how you can identify the different structures on an individual vertebra.

 

A vertebra consists of an anterior part here which is the body, and then you've got the posterior part which consists of the neural arch and all the facets and processes that are attached to that.

 

Here's the body of the vertebra, and then the neural arch is this, I'll just try and get a good view of that, is this arch here, which consists of pedicles - a pair of pedicles here, and the lamina, and then attached to the neural arch you have the transverse processes, and then you've got the superior articular processes, and the inferior articular processes, and you have those on both sides - so there and there. And then at the back you've got the spinous process.

 

That’s seven things that are attached to the neural arch: the superior and inferior articular processes on both sides, the transverse processes and the spinous process. Okay so I'll just rotate that round so you can have a good look. okay, so I’ll just unclick that and take a look at...so that was a thoracic vertebra I showed you there, but if you go further up to the cervical vertebra, you can see that there's another...you've got something else, so in the transverse processes there's a little hole known as the transverse foramen, and you have those on both sides, but you only get these in the cervical vertebrae, because this allows for the passage of the vertebral artery, which I'll show you in a minute.

 

This big hole in the middle which is surrounded by the neural arch is known as the vertebral foramen, and that's where the spinal cord runs, so it's protected by this bony arch that surrounds it. And here again you've got the superior articular facet, you've got the inferior articular facet, and you've got the transverse process sticking out here, which contains the transverse foramen, and then you've got the pedicles and the front and the laminae here, and the spinous process at the back. Body anteriorly. Okay, so let's just take a look at the thoracic vertebra articulating with the ribs here.

 

I've just removed two ribs so you can see how this all works. You can see that the superior. I'll just click...I'll just get that back. Okay, sorry about that. Get rid of these ribs again. Okay, so as I showed you before, you've got a superior articular process and inferior articular process, and these processes articulate with the one above and below.

 

The superior articular process of this vertebra articulates with the inferior process, articular process of the vertebra above. And these joints are known as zygapophyseal joints. And they're synovial joints which help to stabilise the spine and protect and limit movement of the spine.

 

That’s important to know about. And with these thoracic vertebra, they obviously articulate with the ribs, so it's not so clear here on this model, but the tubercle of the rib, this little bump here, articulates with the transverse process of the thoracic vertebra. And the head of the rib, which is here, right at the end articulates with the vertebra, and there are two facets which it articulates with - the inferior demifacet and the superior demifacet, and these are areas on the vertebra which articulate with the head of the rib.

 

The head articulates, the head of the rib articulates with the superior and inferior demifacets and there's a facet on the transverse process which articulates with the tubercle of the rib.

 

That’s how all that works. It's quite simple really, just to recap things, you've got the anterior part, which is the body, you've got the posterior part which is the - just flip back - the posterior part which consists of the neural arch, and attached to the neural arch you've got the superior articular processes, the transverse processes, the spinous process, and the inferior articular processes. And the vertebrae articulate with each other via the superior and inferior articular facets.

 

That’s, those are the main features of the vertebra to be aware of. I'll just quickly show you how the spinal column relates to other structures, so I'll just bring back some blood vessels and some nerves. I just showed you before the - I'll just click on that first - so this is a cervical vertebra, and you can see that because it's got these transverse foramen, and this is where the vertebral arteries run.

 

You can see that there, the vertebral artery coming off the subclavian and then running up through the transverse processes, up  - I haven't got the skull here, but it runs through the foramen magnum and to the base of the brain, where it joins the circle of Willis.

 

Yeah it comes up and joins here at the base of the brain, so that's how, so that's what the transverse foramen is for. And then I didn't show you the - just get rid of the vessels now - so another important thing is the intervertebral foramen...just get rid of this again...so these are these little holes.

 

The word foramen whenever you hear that, it just means a "hole" which allows the passage of structures to pass through, so you've got the vertebral foramen, a big hole in the middle of the neural arch, transverse foramen - a hole in the middle of transverse processes, and this intervertebral foramen, which is a little hole between the articulating vertebrae, and this is where the spinal nerves emerge from.

 

C1 to C7 you have 8 cervical spinal nerves, 8 because the first one emerges above the atlas. If I just bring the nerves back in you can see them coming out of this foramen...if I just remove that, you can see the, you can't quite see the dorsal and ventral roots of the spinal nerves, but they're there somewhere.

 

That’s what the intervertebral foramen are for. And that's that for the vertebrae.