Interactive Transcript
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Knee anatomy.
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Neurovascular bundle and structures.
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Basic.
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Let's begin with the axial projection.
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When you are out on the planes hunting
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for food, your arteries needed to be protected.
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You cut an artery, you bleed to death.
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That's why the arteries are going to be deeper than the veins throughout the body.
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So here's your popliteal artery, which can sometimes be irritated
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and entrapped or encroached upon and develop an adventitial wall cyst.
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Superficial to it,
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although sometimes compressed by structures around it,
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is the popliteal vein. And then superficial to that is the tibial nerve.
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These lie in the popliteal fossa,
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not the popliteus fossa, which is on the lateral side down low,
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there's the popliteus fossa but the popliteal fossa.
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And there are often other smaller vascular structures in the neighborhood.
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These structures can be compressed,
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particularly from cystic masses that arise from the midline.
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They are not usually compressed by structures arising from the gastrocnemius
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semimembranosus bursa, dissecting towards the midline.
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Now, let's take a look at the nerves for a minute.
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Here's the tibial nerve,
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and coming towards the tibial nerve is the peroneal nerve.
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So these will solidify or combine more approximately.
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I don't have a cut high enough to show that.
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As we follow the peroneal nerve down,
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we see it gives off a branch, the lateral sural cutaneous nerve.
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It continues on distally and will follow
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it around the fibula, where it will then divide into sensory and motor branches.
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And they'll have their own separate discussion, so fear not.
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Another vascular structure is the greater saphenous vein.
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It may sometimes be injured or clot.
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It's a superficial vein, and it's usually not a major medical
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concern as long as it's clotted by itself and the deep system is not clotted.
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Do not forget to examine the signal intensity of the venous tissue
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in the knee, for this is one of the cardinal failures of imagers to do.
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I mean, it's okay if you missed a meniscus tear.
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It's not okay if you miss a large popliteal vein thrombosis.
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There is the popliteal vein.
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And typically, at some point, the vein will expand and be bigger than the artery.
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But another way to distinguish them is the artery is deeper than the vein.
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Now, we have a greater saphenous vein,
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which means we ought to have a lesser saphenous vein, which we do.
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It is more posterior,
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we can follow it for a variable distance and then it dives down inferior.
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It will drain into the popliteal vein.
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Although that drainage is not specifically seen here.
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The neurovascular bundle of the knee, focused on the popliteal fossa
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in the midline, or it may be compressed
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or you may have thrombosis, or it maybe affected by adventitial cysts.
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And it is an oft-overlooked part of the search pattern in MRI of the knee.
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In patients with trauma,
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it is critical, especially would need dislocation, to examine the course,
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the shape and the signal of the peroneal nerve, this one being the common peroneal
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nerve and it'll divide into motor and sensory branches as it passes the fibula.
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