USMLE Step 1 Review 02 23 Anatomy Landmarks in the Mouth

USMLE Step 1 Review 02 23 Anatomy Landmarks in the Mouth


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Let’s continue our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

Play USMLE Audio MP3 02 23 Anatomy Landmarks in the Mouth Below


Begin 02 23 Anatomy Landmarks in the Mouth Transcription

Now, we’re going to the look at the landmarks in the mouth as you would see them during an examination.

When you pull the lips back on the top and on the bottom, what is the name of the vertical ridge of tissue that you see attached to the middle of the top and bottom lip?

  • Frenulum of the lip.

Likewise, when you have the patient touch the tip of their tongue to the roof of their mouth, what do you see on the center line of the underside of the tongue in front?

  • The frenulum of the tongue.

What is the name of the bluish veins, which run up the underside of the tongue on both sides of the frenulum?

  • The apical veins of the tongue.

What is the name of the narrow longitudinal fold of tissue extending from the base of the frenulum, back underneath the tongue on both sides?

  • The sublingual folds.

And what gland lies hidden under these two folds?

  • The sublingual glands on each side.  Near the base of the frenulum of the tongue on both sides are seen small holes out of which saliva come.

What is the name of this structure that these salivary outlets are in? 

  • Caruncula lingualis.

The saliva that is excreted from the ducts in the caruncula lingualis come from what salivary glands? 

  • Both the sublingual and submandibular glands.

If the patient cannot elevate their tongue at the midline or keep their tongue elevated, what CN is suspect?

  • CN XII, the hypoglossal.

Now, we ask the patient to drop their tongue.  If their tongue is grossly enlarged, what four conditions come to mind?

  • Mxyedema, amyloidosis, acromegaly, or possibly, a rhabdomyoma present in the tongue.

What non pathological condition could cause a broadening of the tongue?

  • Simply, people without teeth or dentures on the side.

Now, we look at the surface of the tongue.  If it is smooth and pale, what disease are we thinking about?

  • Pernicious anemia.

If it’s smooth and fiery red, what two conditions are we thinking about?

  • Deficiencies of niacin or riboflavin.

What pathology often occurs on the lateral surface of the tongue?

  • Oral cancer.

When we look at the inner surface of the cheeks, what immediately underlies the mucosa? 

  • Buccinator muscle.

And then, what is more superficial to buccinator?

  • Buccal fat.

What is the name of the shallow groove running down the center of the tongue?

  • Median sulcus.

What is the fascial structure which connects the two halves of the tongue at the midline, which underlies the median sulcus?

  • Septum lingui.

As we look at the velvety anterior 2/3 of the tongue, we see two types of structures – smaller ones and scattered larger ones.

What are the many smaller ones? 

  • Filiform papillae.

And what are the scattered larger ones?

  • Fungiform papillae.

The filiform papillae are small elevations of what type of tissue? 

  • Epithelium that is keratinized.

And in what direction do they point?

  • Toward the pharynx.

What are the filiform papillae mostly sensitive to?

  • Touch, textural sensation.

What is the CN nerve for them, then?

  • CN V.

Division and branch?

  • Mandibular division, lingual branch.

What is carried in the larger fungiform papillae?

  • Taste buds.

What are absent?

  • Gustatory glands or taste glands.

The taste sensations gathered by the fungiform papillae and relayed back along the lingual nerve, eventually travel to what CN?

  • CN VII.

What branch of CN VII gathers these sensations from the lingual nerve?

  • Chorda tympani.

As we look further back in the tongue, we see a V-shaped row of 6-12 wart shaped papillae with the point of the V pointing back toward the pharynx.  What are these?

  • Vallate papillae.

Directly behind the vallate papillae, we see a smooth portion of V shaped tissue.  What’s the name for this area?

  • The terminal sulcus.

The entire surface of the tongue in front of the terminal sulcus is referred to as…?

  • The dorsum of the tongue.

And everything behind the terminal sulcus is referred to as…?

  • The root of the tongue.

The vallate papillae, then, are on what part of the tongue?

  • The dorsum.

What do the vallate papillae contain?

  • Taste buds.

What are also present around the vallate papillae?

  • Serous gustatory glands.

And their secretions have what purpose? 

  • To wash away flavors in order to renew the vallate papillae for new tastes.

Along the sides of the tongue, toward the back, are transverse mucosal folds.  What are they called?

  • Foliate papillae.

And what do they contain?

  • Taste buds and serous gustatory glands.

What two papillae, then, on the dorsum of the tongue are innervated by CN VII for taste sensation?

  • Fungiform papillae and foliate papillae.

What papillae then are probably innervated by the glossopharyngeal nerve, CN XI, which innervates the posterior 1/3 of the tongue for taste?

  • The vallate papillae.

Posterior to the V-shaped terminal sulcus on the tongue, we see the root of the tongue covered with a very rugged surface.

What is the name of these structures on the root of the tongue?

  • Lingual follicles.

What is the tiny blind pit that can be seen at the apex of the sulcus terminalis?

  • Foramen cecum.

What is foramen cecum, the embryological point of origin, for?

  • The thyroglossal duct.

In embryological development, what gland grew out of the floor of the pharynx in the region of the tongue before it developed and leaves behind the foramen cecum, its duct of origin, the thyroglossal duct?

  • The thyroid gland.

The four qualities of taste – sour, salty, sweet, and bitter -are detected at different sites on the tongue.

Are there recognizable differences by light or electron microscopy between the taste buds? 

  • No.

No one has yet discovered any real differences between the different taste buds even though they are in different part s of the tongue tasting different qualities of taste.  We’ll just go over some of the areas in a very brief way.

What two tastes are at the tip of the tongue? 

  • Salt and sweet.

What taste is over the middle of the tongue, but not towards the sides of the tongue?

  • Sweet.

Which two tastes are on the sides of the tongue?

  • Sour and salt.

There’s a gradation between the two.  Which of them is stronger on the side of the tongue toward the front?

  • Salt.

And, which is strong on the side of the tongue towards the back?

  • Sour.

And, what is the taste in the region of the vallate papillae?

  • Bitter.

Ok, we’re almost done examining the mouth.  As we look at the roof of the mouth behind the front teeth we have…?

  • The hard palate.

And behind the hard palate, we have..?

  • The soft palate.

And then hanging down in the center from the end of the soft palate, we have..?

  • The uvula.

What are the two pillars of tissue that arch out from the sides to the uvula?

  • The palatoglossal arches.

What are the recesses directly behind the palatoglossal arches on both sides?

  • The tonsilar fossi.

And what is the mass of lymphatic tissue within the tonsilar fossa?

  • Palantine tonsil.

Directly posterior to the tonsillar fossa and the palantine tonsil is another arching pillar, one on each side – what is that?

  • Palatopharyngeal arch.

And then finally behind the palatopharyngeal arches, there is a space stopped by the posterior wall of the pharynx, what is this space?

  • The oropharynx.



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