Hypopharynx - The Piriform Sinus Anatomy
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Hello everyone, Dr. Sydney Levy here continuing our discussion
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3 00:00:05,130 --> 00:00:08,490 of the anatomy of the hypopharynx as a
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prelude to the diagnosis and staging of
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hypopharyngeal squamous cell malignancy.
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I'd like to focus on the piriform sinus.
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This is one of the three subsites of the
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hypopharynx, the other two being the post-cricoid
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space and the posterior hypopharyngeal wall.
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The piriform sinus is the most commonly involved
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subsite of hypopharyngeal squamous cell malignancy.
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And I'd like to draw its boundaries for you
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and explain some of its anatomical relations.
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I have pre-contrast non-fat-suppressed T1-weighted
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imaging in the axial and coronal projections to assist.
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So firstly, let's draw some boundaries.
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On the axial projection, the piriform sinus
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begins at the junction of the medial and
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lateral walls of the aryepiglottic fold here.
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From there, we follow the lateral wall to the
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piriform sinus itself all the way around until
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we reach the same level at which time we cross
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over into the posterior hypopharyngeal wall over
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to the other side where the situation repeats.
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On the coronal projection, we have the epiglottis
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here, and there is a soft tissue fold which connects
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the epiglottis to the hypopharynx, or the piriform
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sinus, which we call the pharyngoepiglottic fold.
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That's actually here, and from there
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we get into the piriform sinus.
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This is the lateral wall
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of the piriform sinus.
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There is the apex.
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And then we head back up to the level at which
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the piriform sinus meets the aryepiglottic fold.
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Now this here is the aryepiglottic fold.
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So this is a little bit difficult to picture,
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but here we have the pharyngoepiglottic fold.
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Here we have the aryepiglottic fold.
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And remember that the lateral wall of
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the aryepiglottic fold forms part of the
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piriform sinus as a space, as a subsite.
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So, summarizing that, the piriform sinus extends
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from the pharyngoepiglottic fold superiorly,
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as far as the junction of the medial and
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lateral walls of the aryepiglottic fold.
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And this also happens to be at the level
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of the superior margin of the post-cricoid
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space, which is at that level, but medially.
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Other regional structures which are worth
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keeping in mind when looking at this region are
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the medial relations within the supraglottic
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larynx, which include the arytenoid cartilages
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here, a little bit further down, and the thyroid
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cartilage, which is this large structure here.
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So in summary, think of the piriform sinus as
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consisting of an apex at the bottom, anterior,
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lateral, and posterior walls. And keep in mind
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that it is situated adjacent to the supraglottic
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larynx at the level of the aryepiglottic folds,
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the epiglottis superiorly, to which it communicates
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via the pharyngoepiglottic fold, and that it is
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continuous with the posterior hypopharyngeal wall,
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medially and posteriorly, and that the post-cricoid
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space is adjacent to its medial margin anteriorly.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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