CHAPTER 14
Oral Cavity
263
Specialized Mucosa
T. Yang
Foliate
papillae
Circumvallate
papillae
Lingual
tonsil
Palatine
tonsil
Fungiform
papillae
Filiform
papillae
Fig. 14-5B
Fig. 14-6A
Fig. 14-5C
Sulcus
terminalis
Palatoglossus
muscle
Oropharynx
A
Figure 14-5A.
Overview of the tongue
.
The inferior surface of the
tongue
and the fl oor of the mouth
are covered by lining mucosa with a nonkeratinized squamous
epithelium. The superior surface of the tongue is covered by
specialized mucosa with numerous projecting papillae includ-
ing
± liform papillae
,
fungiform papillae
,
circumvallate
papillae
,
and
foliate papillae
. The specialized mucosa is attached to the
underlying skeletal muscle. The tongue has a central core of
skeletal muscle, which controls movements of the tongue and
is innervated by the hypoglossal nerve (CN XII). The base of
the tongue is attached to the fl oor of the mouth. The surface
of the posterior third of the tongue has somatosensory recep-
tors and taste buds that are innervated by the glossopharyn-
geal nerve (CN IX). The anterior two thirds of the tongue has
somatosensory receptors that are innervated by the trigeminal
nerve (CN V), and its taste buds are innervated by the facial
nerve (CN VII). The tongue plays an important role in speech,
taste, and in moving and swallowing (
deglutition
) food.
Filiform
papillae
Epithelium
Lamina propria
Skeletal
muscle
B
Figure 14-5B.
Filiform papillae
,
tongue
. H&E,
3
35
The
± liform papillae
are slender, cone-shaped papillae with
keratinized outer surfaces. They are the most numerous but
smallest in size of the four types of papillae. The F
liform
papillae are often packed in rows and cover the entire supe-
rior surface of the anterior two thirds of the tongue (anterior
to the sulcus terminalis). Each F
liform papilla has a central
connective tissue core with several branches of small papillae.
They are the only papillae that do not have taste buds. The
F liform papillae’s tips are keratinized, consistent with their
exposure to abrasion during chewing. Because they have no
taste buds, their main functions are to help with chewing and
mixing food. The submucosal layer is absent in the tongue;
the mucosa of the tongue is strongly bound to the underlying
skeletal muscle to allow optimum food bolus control.
C
Fungiform papilla
Filiform
papillae
L
a
m
in
i
n
a
p
p
ro
r
o
p
ria
r
i
a
E
p
ith
i
t
h
e
liu
l
i
u
m
Epithelium
Skeletal
Skeletal
muscle
muscle
Skeletal
muscle
L
a
m
in
i
n
a
p
p
ro
r
o
p
ria
r
i
a
Lamina propria
Figure 14-5C.
Fungiform papillae
,
tongue
. H&E,
3
44
The
fungiform papillae
are mushroom shaped and much less
numerous than the F
liform papillae. They tend to be slightly
taller than the F
liform papillae that surround them. Each
fungiform papilla has one to F
ve taste buds on its superior sur-
face. These taste buds are innervated by the chorda tympani
branch of the facial nerve (CN VII), which joins the lingual
branch of the trigeminal nerve (CN V). The fungiform papillae
are covered by nonkeratinized squamous epithelium. They are
distributed at the tip and two sides of the tongue (±ig. 14-5A).
In general, the taste buds have F
ve taste sensations: sweet, bit-
ter, umami, salty, and sour. The salty and sour sensations are
associated with ion channels; the other three taste sensations
are associated with G protein–coupled receptors.
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