Cervical Lymph Nodes Levels 5a & 5b
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Hello everyone, it's Dr. Sidney Levy.
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3 00:00:04,090 --> 00:00:07,800 Today I would like to discuss Level 5, or the
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posterior triangle or spinal accessory lymph
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nodes of the lymph node levels of the neck.
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Level 5 has two sublevels, Level 5A and Level
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5B, and I would like to show you the boundaries
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and landmarks in order to quickly identify these
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levels when staging a head and neck malignancy.
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Let us begin with Level 5A.
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I have some pre-contrast,
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T1-weighted imaging in axial and
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sagittal projections to assist us.
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The boundaries that you need to be aware of are
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the posterior border of sternocleidomastoid and the
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anterior border of trapezius in the first instance.
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Let me show you then, sternocleidomastoid,
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trapezius, and there's one other structure
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that's helpful to know as well, and
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that's the scalenus anterior, just here.
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These are the three muscles.
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Level 5A is posterolateral to levels 2 and 3.
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So it covers this region here, the posterior triangle.
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Now, in a sagittal projection, I'll
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show you once again those landmarks.
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This is the trapezius, this is the sternocleidomastoid.
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We're interested in the anterior
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margin of the trapezius.
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And the posterior margin of the sternocleidomastoid.
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Now the only other thing you need to know
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is what separates Level 5A and Level 5B.
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It's just one structure.
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It's the inferior margin of the cricoid cartilage.
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So I will take you out of that.
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We will go to the midline where
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we can find the cricoid cartilage.
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This is the cricoid cartilage here.
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And we are interested in the inferior margin of it.
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If you remember that, and we go off to the side, that
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same landmark is applicable for Level 5A and Level 5B.
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So therefore, if I draw the same plane laterally, and
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then I redraw the anterior margin of trapezius and the
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posterior margin of sternocleidomastoid, we have 5A.
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And anything below the inferior margin of the
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cricoid, down to the clavicle, is within 5B.
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That's 5B.
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That's all you need to remember.
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And in our next vignette, we will cover Level 6.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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