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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.