Development of the Tongue (40

DEVELOPMENT OF TONGUE
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

Contents
• Introduction
• Development of Tongue
• Tongue muscles
• Blood supply
• Nerve supply
• Taste sensation
• Clinical examination
• Applied aspect
• Conclusion
• Bibliography

Introduction
• Tongue is a complex muscular organ that is
anchored to hyoid bone, styloid process,
and genial tubercles of the mandible at the
insertion of 3 extrinsic tongue muscles.
Tongue is divided into
– Anterior part/Oral portion
– Posterior part/Base of the tongue
– Superior part/Dorsum of the tongue
– Under surface/Ventral surfaces

Functions of the tongue
• Ingestion
• Suckling
• Swallowing
• Perception of taste
• Phonation
• Respiration
• Jaw development

Development of tongue
• At about 4 weeks as the pharyngeal
arches meet in the midline beneath
the primitive mouth, local
proliferation of the mesenchyme, then
gives rise to a number of swellings in
the floor of mouth. First swelling
arises in the midline in the
mandibular process and is flanked by
2 other bulges called lateral
swellings. Very quickly these lateral
swellings enlarge and merge with
each other to form a large mass. From
which the mucous membrane of the
anterior two thirds of the tongue is
formed.www.indiandentalacademy.com

• Hyphobronchial eminence – gives rise to the
mucosa covering, the root of the tongue and
epiglotis.
• Muscles of tongue
• Development of papila – lingual epithelium shows
specialization at about 7 weeks when the CV
papilla and foliate papilla first appear.
• Epithelium of tongue – develops from Ectoderm
(Anterior two third)
• Endoderm (Posterior one third)

They start and wholly end
with in the tongue.
They include:
 Superior longitudinal
 Inferior Longitudinal
 Transverse group
 Vertical group
Intrinsic Group:
Tongue Musculature

Extrinsic Group :
Are the group of
muscles that
originate outside
and run into it :
They include:
Hyoglossus
Styloglossus
Palatoglossus
Genioglossus

Papillae
• Tongue is covered with stratified squamous
epithelium, scattered throughout this
epithelium. On the uppermost surface are 4
types of elevated structures known as
papillae.

Types of Papillae
• Fungiform
• Filliform
• Foliate
• Circumvallate

Fungiform papillae
• Present in the anterior
part of the tongue.
• Scattered among the
numerious filliform
papillae at the tip of
the tongue.
• Taste buds are present
in the epithelium on
the superior surface.

Filliform papillae
• Cover the entire
anterior part of the
tongue bye keratinzed
epithelium.
• They form a tough
abrasive surface
involved in
compressing and
breaking food when
the tongue is opposed
to the hard palate.

Foliate papillae
• Pressent on the lateral
margins of the
posterior part of the
tongue.
• Few taste buds are
present in the
epithelium of the
lateral walls of the
ridges.

Circumvallate papillae
• Adjacent and anterior to
the sulcus terminalis
• 8 to 12 in number
• Surrounded by a deep
circular group into which
open the ducts of minor
salivary glands.
• Epithelium covering the
lateral walls is non
keratinised and contains
taste buds.

Lingual Tonsils
• Situated near the mid line on the dorsum of
the tongue just behind the vallate papillae.
• Is a lymphoid tissue similar to the paletine
tonsil.
• Infection in this part of tongue will involve
the tonsils. Therefore it is an important
indicator of tonsillar infections.

• Defined as a
specialized receptor
that occurs in the oral
cavity, pharynx and
within the epithelium
soft palate.
• Most of them are
found in fungi form,
foliate and CV papilla
of the tongue.
Taste buds

Histology
• Taste bud is a barrel shaped structure
composed of 30-80 spindle shaped cells.
These cells are separated from the
underlying CT by the basement membrane.
Type 1 & 2 – sustentacular cells
Type 3 – gustatory receptor cells
• Outer surface if covered by flat epithelial
cells, which surrounds a small opening.
• Outer supporting cells are arranged like the
staves of a barrel.

• Sweet (at the tip) - fungi
form papillae
• Salt (antero lateral border)
– fungi form papillae
• Bitter (posterior part in the
middle) – CV papillae
• Sour (posterior part in the
lateral areas) – Folliate
papillae.
• Special type of receptor
whose function is to detect
the taste of water has been
identified in the region of
CV papillae.
Primary taste sensation

Gustatory path way

Blood supply
• Anterior two thirds – deep lingual artery
• Posterior one third – dorsal lingual artery to
the base of the tongue.

• Motor nerve: All the intrinsic and extrinsic
muscles of the tongue except palatoglossus by 12th
cranial nerve. Palatoglossus is supplied bycranial
part of the accessory through the pharyngeal
complex.
• General sensation - Lingual nerve.
• Taste sensation - Chorda tympani for the anterior
two thirds of the tongue.
• Glossopharyngeal for the posterior one third and
also for the general sensation.
• Posterior most part is supplied by the vagus
through the internal laryngeal nerve
Nerve supply

Clinical examination of tongue
• Nutritional deficiencies
• Pernious anemia
• Vitamin B complex
deficiency
• Diabetes mellitus

• Impairment of local
immune mechanisms
where the langerhan’s
cells is decreased.
• Impairment of local
blood supply
• Diabetes mellitus
• Fungal infections

• Tongue in tertiary
syphillis is affected by
gumma formation or a
more diffuse chronic
granulomatous lesion
– interstitial glossitis.
• Tongue exhibits non
ulcerating irregular
indurations with an
asymmetric pattern of
groves covering the
entire dorsun.
• Interstitial glossitis

• Rounded or roughly
lozenge shaped, raised
aera that occurs in the
midline of the tongue
dorsum.
• Anterior to the vallate
papilla, affected area
is devoid of filliform
papillae.
• Median rhomboid glossitis

• Lesion of unknown
etiology. It may be related
to emotional stress.
• Desquamation of the
filliform papillae in an
irregular circinate pattern.
• Margins of the lesion are
hyperkeratotic and
acanthotic in some areas.
• Treatment is empirical.
• Geographic tongue

• Characterized by
hypertrophy of the
filliform papillae with
lack of normal
desquamation.
• Fungal infections may
incite this condition.
• Oral use of certain
drugs like pencilin,
aureomycin may incite
this condition.
• Hairy tongue

• Clinically manifested
by numerous small
furrows or groves
often radiating from a
central groove along
the midline on the
dorsal surface.
• Develop
simultaneously as a
sequel to geographic
tongue.
• Fissured tongue

Palpation
• Ask the patient to protrude the tongue on to
gauze
• Aided bye the gauze dentist can hold the
tongue while using the mirror to observe
• Palpation of the tongue should be done both
left to right and vice versa
• The targeted areas are the lateral borders
and the region of valate papillae

Abnormalities of taste
• Ageusia
Complete
Partial
• Hypogeusia
• Dysgeusia
• Cacogeusia
• Torquegeusia
• Gustatory agnosia – loss of ability to classify
contrast or identify a given taste stimulus

Macroglossia
• Causes
• Down’s syndrome
• Congenital
lymphangioma
• Congenital
hypothyroidism
• Neurofibromatosis
type 1
• Pompe’s disease
• Hurler syndrome

Clinical importance
• Due to long term edentulousness tongue
will expand, introduction of a new denture
will be met with dislodging competition
from the tongue.
• Repeated guiding and tongue exercise will
help in altering the size to some extent, over
a period of time tongue will adapt to the
new environment.
• Surgical trimming has been used to reduce
the bulk of tissue present in severe cases.

Ankyloglossia
• Tongue type is defined on
the basis of in ability to
extend the tip of the tongue
beyond the vermillion
border of the lip.
• Syndromes
orofacial digital syndrome
trisomy 13
vanderwoode’s
glasoopalatine ankylosis

Clinical importance
• Severe degree of ankylosis of an exhibit
midline mandibular diastema and lingual
mandibular periodontal defects.
• Difficulty in making the impression which
hampers the retention of denture.
• Altered speech
• Correction
• Mild – speech therapy
• Severe – clipping of frenum

Position of tongue
• Tongue position is important to the prognosis of the
mandibular denture.
• Classification of tongue position :
• Class I
• Tongue lies in the floor of the mouth with the tip forward and
slightly below the incisal edges of the mandibular teeth.
• Class II
• Tongue is flattened and broadened but the tip is in the normal
position.
• Class III
• Tongue is retracted and depressed in to the floor of the mouth
with the tip curled upward,downward or assimilated in to the
body of the tongue.

Role of the tongue in speech
• Speech adaptation to new complete dentures
normally takes 2 to 4 weeks after insertion.
• Sounds like this,that,these are made with the tip of
the tongue extending slightly between the upper
and lower teeth.
• This will provide for labio lingual positioning of
the anterior teeth.
• If about 3 mm of tip is not visible, the anterior
teeth are probably too forward in placement.
• Also if the vertical overlap is excess that does not
allow sufficient space for the tongue to protrude
between the anterior teeth.

• Linguo alveolar sounds: t,d,s,z,v&l
While pronouncing these sounds the tip of the
tongue contacts with the most anterior part of the
palate or lingual aspect of the anterior tooth.
• Sibilant sounds:
Alveolus and tongue form the controlling valve.
S- It’s articulation is mainly influenced by the teeth
and palatal part of the maxillary prosthesis.
The tongue’s anterior dorsum forms a narrow groove
near the mid line with a cross section of about 10
mm.The size and shape of the space will determine
the quality of the sound.
If the opening is too small- a whistle is heard.
If the space is too broad- a lisp is heard.

Bibliography
• Human embryology – I.B.singh 7th Edition
• Human Anatomy – B.D.Chaurasia Vol 3
• Oral Histology – A.R.Tencate 10th
Edition
• Oral Histology – Orban 5th
Edition
• Human Physiology – Guyton 8th
Edition
• Treatment for edentulous patients– Carl O
Boucher 10th
Edition
• Text Book on Complete Dentures – John
Joseph Sharry

Thank you

Development of the Tongue (40

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