Cervical Lymph Nodes Level 3
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Hello everyone.
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It's Dr. Sidney Levy here.
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Today I'd like to discuss Level 3 of
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the lymph node levels of the neck.
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This is the middle internal jugular or deep cervical chain.
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I would like to use pre-contrast T1-weighted imaging to
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demonstrate its boundaries and to show you key landmarks
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to help you identify Level 3 and distinguish it from
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Level 2, Level 4, and Level 5, which surround it.
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So, Level 3, first thing to remember is that it is
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situated inferior to Level 2 and superior to Level 4,
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and it is situated anterior and medial to Level 5.
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The key landmarks to consider are in the supero-inferior
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plane, the hyoid bone and the cricoid cartilage.
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So let me start off by demonstrating those for you.
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It's easiest to see in the sagittal plane.
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This is the hyoid bone here.
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One way you can easily tell is that there are extrinsic
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tongue muscles, such as geniohyoid, which attach to it.
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You can always cross-correlate with the axial projection.
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The next structure you need to be
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aware of is the cricoid cartilage.
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The cricoid cartilage actually sits here.
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And we are interested in the inferior margin of the
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cricoid cartilage as well as the inferior margin
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of the hyoid bone.
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Anything between those two boundaries is within Level 3.
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The other boundary you need to consider is
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the boundary between Level 5 and Level 3.
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And this is formed by the posterior
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border of sternocleidomastoid.
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So anything that is posterior or lateral to the
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posterior margin of sternocleidomastoid, so that's here,
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is within Level 5, whereas anything medial or anterior
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to the posterior border of sternocleidomastoid is within
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Level 3, remembering the superior and inferior boundaries.
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Now that's almost it.
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There is one other landmark you need to be aware
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of, particularly more inferiorly, and that is
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the boundary between Level 3 and Level 6.
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So Level 6 comes into play in the vicinity of
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the laryngeal cartilages and the thyroid gland.
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It is the anterior compartment, and Level 3
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lies lateral to it, and what you need to remember
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for that is the internal carotid or common carotid
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artery and, in particular, the medial margin.
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So anything medial to the medial margin of the internal
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carotid artery is going to be within Level 6 anteriorly.
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The last thing I'd like to do is to just put all
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of that together and draw Level 3 for you at
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a given plane, just to give you some orientation.
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So if we have the hyoid here,
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we have the cricoid here, let's peek
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halfway in between, let's find a good
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image of the carotid artery, just there.
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In this case, it'll be the common carotid artery.
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And we just need to remember that we are
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between the inferior border of the cricoid
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cartilage and the inferior border of the hyoid.
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We are lateral to the medial margin
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of the internal carotid artery.
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And we are anterior and medial to the
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posterior border of sternocleidomastoid.
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So if we remember all of that, we find ourselves in
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Level 3 here, with Level 5 out here, Level 6 in here,
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Levels 2A, 1B, and 2B there, and Level 4 below.
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In our next vignette, we will discuss Level 4.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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