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Hello everyone,

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Dr. Sidney Levy here.

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Today I would like to discuss the anatomy of

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the larynx as a prelude to the diagnosis and

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staging of laryngeal squamous cell carcinoma.

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I would like to begin by drawing and describing the

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boundaries of the larynx and its adjacent spaces.

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I have a sample case here which consists of a

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relatively advanced, uh, glottic laryngeal malignancy.

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But for the moment I'd like to use it to demonstrate the

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boundaries of the larynx and to outline its subsites.

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So starting off in the sagittal projection, I will begin by

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drawing the superior and inferior boundaries of the larynx.

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The larynx begins at the junction of the

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laryngeal surface of the epiglottis, which

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is considered part of the oropharynx,

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and the aryepiglottic folds to

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which the epiglottis attaches.

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That may be defined at this level.

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The inferior margin of the larynx is the

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inferior border of the cricoid cartilage.

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And that may be outlined at this level here.

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So now we have superior and inferior margins of the larynx.

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Now, it's important to mention that the

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larynx sits anterior to the hypopharynx,

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in particular, the postcricoid region.

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So we need to be comfortable with the laryngeal inlet.

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The laryngeal inlet is situated here.

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So everything posterior and inferior to

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that level belongs to the hypopharynx.

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Everything anterior and inferior to it belongs to

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the supraglottic larynx and the rest of the larynx.

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So from here, we can then trace the posterior

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wall of the larynx down to the level of

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the lower border of the cricoid cartilage.

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And then from that same level, we can trace it up,

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forgetting the malignancy that's there for the moment,

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all the way up to the level of the laryngeal inlet.

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And there we have the larynx.

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So above this level, we have the oropharynx.

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Posterior to this level, we have

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the hypopharynx in this region here.

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It is also worth remembering that there are structures

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within the deep tissues of the neck, such as the

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thyrohyoid membrane, anterior commissure thyroid

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cartilage and cricothyroid membrane, as well as the

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anterior arch of the cricoid cartilage, which are

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within the larynx as an anatomical site, but to which

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we do not consider to be part of the mucosal space.

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So they all sit in this plane here.

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Posterior to the larynx, and anterior to the hypopharynx,

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we have the arytenoid region, the interarytenoid

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space, and the posterior arch of the cricoid cartilage.

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So if I try and draw it in the axial projection for you,

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forgetting the malignancy, this is the

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larynx here in terms of the laryngeal mucosal space.

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These are the laryngeal cartilages.

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We have the cricoid cartilage here.

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The arytenoid cartilages lie at the superior

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margin of the posterior cricoid cartilage.

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And then we have the thyroid cartilages, which have been

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partially eroded here, but would sit in this plane.

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And then posterior to this level, we have

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the hypopharynx, including the postcricoid

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region and the posterior hypopharyngeal wall.

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So in summary, the larynx is bounded by

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the oropharynx superiorly, the hypopharynx

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posteriorly, and consists of mucosal tissue, but

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also laryngeal cartilages and their membranes.