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To introduce you to the normal anatomy of the

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lumbar disc. I have here on the left,

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an axial T2-weighted scan, and on the right,

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a sagittal T2-weighted scan.

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Again, with bright CSF identifying it as T2-weighted

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imaging and the diagram in the center.

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So looking at the left hand image on the axial plane,

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you notice that there is a gradient of

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signal intensity within the disc.

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So here we have a darker area around the

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periphery and a central area, which is a little

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bit brighter in signal intensity.

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This would correspond on the sagittal scan with

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the darker area in the anterior and posterior

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portion around the periphery of the disc,

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which would represent what has been depicted on

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the diagram as the annulus fibrosus

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with the more central

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brighter signal intensity tissue on the sagittal

0:57

scan and T2-weighted scans as the nucleus pulposus.

1:03

On this scan, you are identifying on the axial

1:07

plane the spinous process and the lamina.

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And we're getting into the facet joint as well.

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Within the spinal canal,

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we are able to see the thecal sac

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with the nerve roots centrally located

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within the thecal sac. And again,

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this would pretty much correspond to the axial

1:30

plane through approximately the L3-L4 level

1:34

on the sagittal scan.

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The diagram shows us some anatomy that is not

1:39

present on the axial scan, and that is the facet

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joint with the superior articular facet and the

1:47

inferior articular facet,

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identified here as the facet joint.

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And usually, we do see some differentiation

1:56

between the two bones of the actual joint space,

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and one of the things that we do pay attention to

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with respect to that joint space is how bright it is.

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Because with high signal intensity

2:08

in the facet joint space,

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we usually will imply that there is either some

2:14

element of inflammation or irritation

2:17

or potentially even an effusion.

2:19

This diagram also shows the dorsal root ganglion,

2:24

depicted as DRG here on the right side.

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So we're probably identifying a portion of it on

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the left side here on the T2-weighted scan.

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It's usually seen a little bit more medially located

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than where I've just made the markings, however,

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and better depicted on the diagram.

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The lateral recess is marked here on the diagram.

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With regard to the lateral recess,

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I usually will refer to that when I am seeing

2:56

the pedicle of the lumbar spine.

3:00

So with the pedicle of the lumbar spine, you come

3:03

into a sort of more triangulated appearance of

3:08

the epidural space. And within that, you would

3:12

identify that area that's just medial to

3:14

the pedicle as the lateral recess.

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Lateral recess is also going to be talked...

3:19

we're also going to be talking about the

3:21

subarticular zone when we refer to the locations of disc.

3:25

The neural foramen is demonstrated in red on the

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diagram and is this portion of the anatomy

3:33

on the axial T2-weighted scan.

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And as you get beyond the neural foramina, we

3:39

have an area that people will refer to as the

3:42

far lateral zone or extraforaminal region.

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So with this in mind,

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let's start to look at some cases and

3:51

evaluate the lumbar spine on MRI scans.