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Hello everyone.

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It's Sydney Levy here, continuing our

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discussion of the anatomy of the oropharynx.

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Today I'd like to focus on the tongue base.

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So once again, I've got some pre-contrast

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T1-weighted imaging without fat suppression.

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I'd like to draw the tongue base for you and

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describe its boundaries and its contents.

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Now in this particular case,

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there is a tongue base lesion.

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So let's get that out of the way first.

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This is a tongue base squamous cell carcinoma.

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We will discuss the diagnosis and assessment

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of that in a subsequent vignette, but for

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the purposes of this educational session,

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we will concentrate on the anatomy.

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So the first thing to look for or I like to look for is

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the junction, the anterior boundary of the tongue base,

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which is the line of the circumvallate papillae, and

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the line of the circumvallate papillae is often readily

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distinguished on the axial projection, T1 that is.

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Because you see a change in the

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architecture of the tongue tissue.

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On the sagittal projection, it's a little more

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difficult, but it tends to be at a similar

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level to the junction of the hard palate and

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the soft palate, which you can always find.

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This is the soft palate.

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This is the hard palate.

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This is the junction of the two.

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That will be the junction of the anterior two

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thirds of the tongue and the posterior third.

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You can always remember that it'll also be roughly

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two-thirds of the way down from the tip of the tongue.

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Once you've established that, we're

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going to head posteriorly and laterally.

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And the axial projection's easiest for that.

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So I'm just going to follow down, and we're

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going to get as far as the free margin.

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That's your tongue base seen obliquely.

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In the axial projection.

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In the sagittal projection,

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we can see a bit more of it.

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We head down, past the tongue, around the

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tumor, don't worry about that; that's an ulcer,

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don't worry about that, down to the valleculae,

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which are actually collapsed by this tumor.

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The valleculae are recesses on either side

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of the midline from which the epiglottis

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projects posteriorly into the pharynx.

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The tongue base ends at the junction

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of the lingual surface of

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the epiglottis and the laryngeal surface.

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So the laryngeal surface of the epiglottis

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belongs to the supraglottic larynx, whereas the

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lingual surface belongs to the base of tongue.

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What are the contents of the base of tongue?

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The main contents that we need to be aware of are the

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lingual tonsils, which are sometimes distinguishable as

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discrete structures, but often more readily appreciable

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as slight thickenings of the mucosa in this region.

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So in summary, I've drawn the mucosal surface of the

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base of tongue, and the take-home messages are, look

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for the line of the circumvallate papillae anteriorly,

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and then look for the junction of the lingual and

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laryngeal surfaces of the epiglottis inferiorly.

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And then laterally, we have the palatine tonsils

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which are actually posterolateral to the tongue base.

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Thank you.