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The tongue

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Surface anatomy of the tongue

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Quick overview

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Introduction
• The tongue is a mass of muscle that is almost completely
covered by a mucous membrane. It occupies most of the oral
cavity and oropharynx. It is known for its role in taste, but it also
assists with mastication (chewing), deglutition (swallowing),
articulation (speech), and oral cleansing

15.
What color should a healthy tongue
be?
• A healthy tongue is typically pink, though the shades of
light and dark can vary. If your tongue is discolored, it
could indicate a health problem.

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• As is the case with all of anatomy, it is important to understand
the terminology associated with describing the structures of
interest. The prefix gloss- and the suffix -glossus are commonly
used with reference to the tongue.
• Therefore, the name glossopharyngeus refers to the muscle
arising from the tongue and inserting in the pharynx.
• Similarly, the name hyoglossus speaks of a muscle originating
at the hyoid bone and inserting in the tongue.

17.
• Glōssa means tongue or language in Greek, hence the relation
with glossus.
• Hypo, from Greek, means under or beneath. It is a very useful
prefix!
• Lingua to lingualis / lingual, which means tongue, language or
speech in Latin. This is where we get language or a logo
(although logos is Greek for word or reason).

18.
Mucous membrane of the Tongue
• The mucous membrane of the upper surface of the tongue can be
divided into anterior and posterior parts by a V-shaped sulcus, the
sulcus terminals.
• The apex of the sulcus projects backward and is marked by a small pit,
the foramen cecum.
• The sulcus serves to divide the tongue into the anterior two thirds, or
oral part, and the posterior one third, or pharyngeal part.
• The foramen cecum is an embryologic remnant and marks the site of
the upper end of the thyroglossal duct. Three types of papillae are
present on the upper surface of the anterior two thirds of the tongue:
the filiform papillae, the fungiform papillae, and the vallate papillae.

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The mucous membrane covering the posterior third of the longue is
devoid of papillae (without papillae) but has an irregular surface,
caused by the presence of underlying lymph nodules, the lingual tonsil.
The mucous membrane on the inferior surface of the tongue is
reflected from the tongue to the floor of the mouth.
In the midline anteriorly, the undersurface of the tongue is connected
to the floor of the mouth by a fold of mucous membrane, the frenulum
of the tongue.

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• On the lateral side of the frenulum, the deep lingual vein can be seen
through the mucous membrane.
• Lateral to the lingual vein, the mucous membrane forms a fringed fold
called the plica fimbriata

22.
Tongue Papillae
• There are four types of lingual papillae found on the
surface of the human tongue
Filiform papillae
Fungiform papillae
Foliate papillae
Circumvallate (Vallate) papillae

23.
Filiform papillae
• Filiform papillae are the most abundant
of the four types of papillae. shaped
like cones and are
• found over the entire surface of the
tongue, giving it its rough appearance
• By making the dorsal surface of the
tongue rough, these papillae
provide friction to allow movement of
the food bolus during chewing. It
should be noted that these papillae do
not possess taste buds.

24.
Fungiform papillae
• Fungiform papillae are weakly
keratinized and less abundant
than the filiform papillae.
These highly vascular,
mushroom-shaped papillae
contain a few taste buds on
the apical aspect.
• Found at the tip and sides of the
tongue
• Fungiform papillae consist
of approximately 1,600 taste
buds.

25.
Foliate papillae
• Foliate papillae appear as bilaterally
paired, parallel, longitudinal slits or
series of folds on the posterolateral
margin of the tongue, near the
sulcus terminalis. The mucosa is
non-keratinized and the papillae are
populated with
numerous taste buds. Each person
has about 20 foliate papillae,
which contain several hundred
taste buds.

26.
Circumvallate (Vallate) papillae
• Circumvallate (Vallate) papillae are
organized linearly, as a set of four
to six large papillae anterior to
each limb of the sulcus terminalis
(i.e. eight to twelve, or fourteen
papillae in total).
• Circumvallate (Vallate)
papillae appear larger than the
other types of papillae, and they
contain approximately 250 taste
buds.

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Taste buds
• There are five basic tastes that stimulate the
taste buds, including:
1.Sweet.
2.Salty.
3.Bitter.
4.Sour.
5.Umami (savory).
• There’s a common misconception that
different areas of the tongue taste different
things. In reality, all of taste buds have the
ability to detect all five flavors — some regions
of the tongue are just slightly more sensitive
to certain tastes.

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• While taste buds are distributed throughout the entire oral
cavity, they are at higher concentrations on the tongue. Each
taste bud is clear, oval and covered by stratified squamous
epithelium.
• A combination of elongated taste (gustatory), supportive,
and basal stem cells can be found within each taste bud.

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• There are five gustatory sensations that are perceived by
individuals. These are sweet, salty, sour, bitter, and umami. The
microvilli found on the apical surface of the taste cells are
equipped with various receptors that bind to varying molecules.
The reaction generated from this compound-receptor interaction
gives rise to varying action potentials that are subsequently
perceived as taste.
• Saltiness is often associated with the cationic component of a
compound (i.e. sodium ions), while sourness is related to the
acidity (concentration of hydrogen ions) in the
compound. Organic compounds such as carbohydrates or
amino acids give rise to sweet taste, while bitterness is
associated with long-chain organic compounds. The final taste -
umami - also known as savoury, is related to compounds with
the left-handed chiral isomer of glutamic acid.

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Muscles of the Tongue
The tongue is composed of two types of muscles:
• Intrinsic
• Extrinsic

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Intrinsic muscles
Confined to tongue
No bony attachment
Consist of:
• Longitudinal fibers
• Transverse fibers
• Vertical fibers
• Function: Alter the shape of the tongue

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Extrinsic muscles
Connect the tongue to the surrounding structures: the soft
palate and the bones (mandible, hyoid bone, styloid process)
Include:
• Palatoglossus
• Genioglossus
• Hyoglossus
• Styloglossus
Function: Help in movements of the tongue

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Movements
• Protrusion:
 Genioglossus on both sides acting together
• Retraction:
 Styloglossus and hyoglossus on both sides acting together
• Depression:
 Hyoglossus and genioglossus on both sides acting together
• Elevation:
 Styloglossus and palatoglossus on both sides acting together

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Sensory Nerve Supply
Anterior ⅔:
• General sensations: Lingual nerve
• Special sensations : chorda tympani
Posterior ⅓:
• General & special sensations: glossopharyngeal
nerve
Base:
• General & special sensations: internal laryngeal
nerve

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Motor Nerve Supply
Intrinsic muscles:
 Hypoglossal nerve
Extrinsic muscles:
 All supplied by the
hypoglossal nerve, except
the palatoglossus
The palatoglossus supplied by
the pharyngeal plexus

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Blood Supply
• Arteries:
Lingual artery
Tonsillar branch of facial artery
Ascending pharyngeal artery
• Veins:
Lingual vein, ultimately drains
into the internal jugular vein

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Lymphatic Drainage
• Tip:
• Submental nodes bilaterally &
then deep cervical nodes
• Anterior two third:
• Submandibular unilaterally & then
deep cervical nodes
• Posterior third:
• Deep cervical nodes
(jugulodigastric mainly)

38.
Tongue functions
• The tongue is the most important articulator for speech production.
During speech, the tongue can make amazing range of movements
• The primary function of the tongue is to provide a mechanism for
taste. Taste buds are located on different areas of the tongue, but are
generally found around the edges. They are sensitive to four main
tastes: Bitter, Sour, Salty & Sweet

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• The tongue is needed for sucking,
chewing, swallowing, eating,
drinking, kissing, sweeping the
mouth for food debris and other
particles and for making funny faces
(poking the tongue out, waggling it)
• Trumpeters and horn & flute players
have very well developed tongue
muscles, and are able to perform
rapid, controlled movements or
articulations

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Clinical Notes
Lacerations of the tongue
Tongue-Tie (ankyloglossia)
(due to large frenulum)
Lesion of the hypoglossal
nerve
• The protruded tongue deviates
toward the side of the lesion
• Tongue is atrophied & wrinkled