Cervical Lymph Node Levels 1A and 1B
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Hello everyone, it's Dr. Sidney Levy here and today we will be
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3 00:00:05,020 --> 00:00:08,060 talking about lymph node levels of the neck.
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Lymph node levels of the neck are an important
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fundamental piece of knowledge in order to
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be able to stage head and neck malignancy.
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And I would like to take you through each of the
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accepted lymph node levels and draw them for you on
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MRI images so that you can quickly identify them.
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The first vignette will be on Level 1, which is
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the submental and submandibular lymph node group.
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Level 1 is split into two
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sublevels, Level 1A and Level 1B.
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Level 1A is the submental group, and
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Level 1B is the submandibular group.
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I will use these pre-contrast T2 and T1-weighted
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images to demonstrate the boundaries for you.
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Firstly, Level 1A.
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The structures that you need to be familiar with are
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the anterior belly of the digastric and the hyoid bone.
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On the axial projection, the anterior belly of
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the digastric is found here and here, so these two muscles.
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It is often difficult to locate them on a
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single slice, and because of that, I suggest
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that you become familiar with scrolling from
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the origin of the posterior belly of the digastric
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inferiorly into the anterior belly, where
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it will eventually insert on the hyoid bone.
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The hyoid bone is the next structure
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that's important, and that's here.
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It can be located on any plane, but sometimes,
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it's easy to get an appreciation of the
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vertical level by using the sagittal plane.
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And an easy way to find it is that many of the
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extrinsic muscles of the tongue actually insert on it.
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We have the geniohyoid, for instance.
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And once you're comfortable with those structures, what
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you need to remember is that the submental level is
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anterior and medial to the anterior belly of the digastric.
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So, to reinforce what I've been talking
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about, we can consider the submental level
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to be in this region here, remembering that
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the anterior belly of the digastric is here.
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In a vertical plane, you just need to remember that
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it is superior to the inferior margin of the hyoid.
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So, therefore, you are looking
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at lymph nodes in this region.
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Now, onto Level 1B.
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Level 1B is the submandibular lymph node group.
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And the first thing to remember is that it is lateral,
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and posterior to the submental group.
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Its important landmarks are very similar.
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Once again, you have the anterior belly of the digastric.
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But this time, you have to designate the
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boundary between Level 1B and Level 2A.
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And the important landmark to remember is the
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posterior border of the submandibular gland.
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So, if you draw a plane here to remember
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where our anterior belly of the digastric is,
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the submandibular, or Level 1B level, is lateral
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to the anterior belly of the digastric and anterior
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to the posterior border of the submandibular gland.
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So, if I scroll for you,
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you will often locate lymph nodes
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in close proximity to the
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inferior margin of the mandible.
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But this is the region that we're concerned with.
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In our next vignette, we will discuss Level 2A
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and Level 2B, which are posterior to Level 1B.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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