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MRI anatomy, the quadriceps and extensor mechanism.

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We've got the quadriceps femoris tendon or quad. tendon, which continues on down atop

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or superficial, to the patella as the prepatellar plate,

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analogous to the prepubic plate and the pelvis, and then continues on down

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as the patellar tendon that inserts on the anterior tibial tubercle.

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There is a bursa located anteriorly

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and also some fascial tissue, which I'll artificially kind of draw in right here.

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There's some fascia beneath it and superficial to it,

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and this area can separate from the quadriceps and prepatellar plate.

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And this is known as fascia degloving or Morel-Lavallée syndrome.

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We also have a bursa up here, and this is one of the potential sites

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where impingement syndrome can occur in the knee.

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Another site is the fat pad that sits

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below the patella that can hypertrophy or indurate and cause symptoms.

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And another site of impingement is the iliotibial band bursa and iliotibial

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band itself riding over the lateral thermal condyle,

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and that'll be a separate subject.

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But these fat pads are important and are

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not to be ignored in conjunction with analysis of the quad,

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the prepatellar plate, and the patellar tendon.

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So now let's move into another slide in the axial projection

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that demonstrates, from our Total Body Atlas, the prepatellar plate that sits

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in front of the patella, that has some slight undulation on either side, is

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the lateral and medial quadriceps retinaculum.

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And the quadriceps retinaculum

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on the lateral side contributes to layer two of the LCL.

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Now, not drawn in here, there are some wispy fibers that will

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represent layer one, and that has been discussed in a separate vignette.

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This prepatellar plate is another oft-ignored structure.

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But look at the layers that sit in front of the patella.

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We've got skin, we've got the prepatellar subcutaneous bursa.

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We've got a transverse layer of fascia.

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We've got a prepatellar subfascial bursa.

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So there's actually two bursae.

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I only showed you one in a diagram for simplicity.

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Then we have an intermediate oblique aponeurotic layer,

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a prepatellar subaponeurotic bursa.

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Now, we have three bursa layers.

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And then finally, the longitudinal rectus

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femoris fibers that continue over the top of the patella.

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So I'm going to explain to you how

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the quadriceps femoris is made up of four different muscle groups.

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But it's only the rectus femoris

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that continues longitudinally over the superficial aspect of the patellar bone.

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So the other layers will drop out.

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And we'll see this on MRI when we show it in a moment.

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In the coronal projection, the quadriceps tendon fans out.

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It has a rather striated appearance.

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And I'm going to show you an MRI where

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there's just a tiny bit of inflammation to accentuate those striations.

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On the medial side,

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we've got the VMO tendon and some peripatellar retinacular tissue,

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and the VLO tendon and peripatellar retinacular tissue.

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There will be little bands that go off

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to the sides representing the quadriceps femoris retinaculum,

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going both medially and laterally but more prominent laterally.

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And here again, showing you the peripatella retinacula, the VMO tendon,

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the VLO tendon,

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and there will be contributions to those by the quadriceps femoris.

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So now, let's have a look at this anatomy on MRI

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and begin with a sagittal projection.