The Posteromedial Corner: Semimembranosus Expansions part 4
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Knee anatomy.
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Posterior medial corner on MRI, lateral view.
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Let's look at some of the
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minor arms of the semimembranosus expansion.
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You've already heard about the major arm,
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which I'm making a little bit brighter.
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You saw it as a dotted orange structure.
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It is the direct arm,
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or deep head or deep expansion of the semimembranosus.
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Now, I'm going to take it away because it has sent off another
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bifurcation anteriorly, known as the anterior arm.
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The anterior arm goes underneath the POL and it'll
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insert somewhere around this location.
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Now, we've also got higher up,
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already reflected off before you get to the joint line,
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the capsular arm, and it makes a little arc.
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It merges with the joint capsule and it also merges
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with fibers of the posterior oblique ligament.
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In fact, it merges with a capsular or
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superior arm of the posterior oblique ligament.
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The inferior or popliteal arm passes beneath the POL.
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So it's underneath this green structure. Here's the inferior
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or popliteal arm right there, underneath the POL.
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And it attaches to the tibia just above the insertion
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of the deep portion of the superficial MCL,
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which many of you know as the tibial collateral ligament.
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So the insertion of the tibial collateral ligament lies
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in very close proximity to this structure right here,
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which is the inferior or popliteal arm
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of the semimembranosus expansion.
Stephen J Pomeranz, MD
Chief Medical Officer, ProScan Imaging. Founder, MRI Online
ProScan Imaging
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