ORAL CAVITY II

Dr. Nabil Khouri MD, PhD

THE TONGUE

Mass of striated muscles covered with the mucous membrane

Divided into right and left halves by a median septum

Three parts:

Oral (anterior ⅔)

Pharyngeal (posterior ⅓)

Root (base)

Two surfaces:

Dorsal

Ventral

FUNCTIONS

The tonge 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

DORSAL SURFACE

Divided into anterior two third and posterior one third by a V-

shaped sulcus terminalis.

The apex of the sulcus faces backward and is marked by a pit

called the foramen cecum

Foramen cecum, an embryological remnant, marks the site of the

upper end of the thyroglossal duct

Anterior two third: mucosa is rough, shows three types of

papillae:

Filliform

Fungiform

Vallate

Posterior one third: No papillae but shows nodular surface

because of underlying lymphatic nodules, the lingual tonsils

PAPILLAE

CIRCUMVALLATE

PAPILLAE are arranged

in a row parallel to and in

front of sulcus terminalis

FUNGIFORM PAPILLAE

are numerous at the tip

and margin of the tongue.

FILLIFORM PAPILLAE

are prevalent on the

dorsum of the tongue

arranged in rows parallel to

sulcus terminalis

VENTRAL SURFACE

Smooth (no papillae)

In the midline anteriorly, a mucosal fold, frenulum connects the tongue with the floor of the mouth

Lateral to frenulum, deep lingual vein can be seen through the mucosa

Lateral to lingual vein, a fold of mucosa forms the plica fimbriata

MUSCLES

The tongue is composed of two types of muscles:

Intrinsic

Extrinsic

The intrinsic M

Confined to tongue

No bony attachment

Consist of:

▫ Longitudinal fibers

▫ Transverse fibers

▫ Vertical fibers

• Function: Alter the shape of

the tongue

MUSCLES OF THE TONGUE INTRINSIC MUSCLES

MUSCLE FUNCTION

SUPERIOR

Shortens

tongue; curls

apex and sides

of tongue

INFERIOR Shortens

tongue; uncurls

apex and turns

it downward

TRANSVERSE Narrows and

elongates

tongue

VERTICAL Flattens and

widens tongue

All intrinsic muscles are supplied by Hypoglossal nerve

muscle Origion and insertion Action

Transverse muscle

From the median septum and pass lateraly to be inserted into the side of the tongue.

Narrow and elongate the tongue.

Superior Longitiudinal muscle

Attached to the mucus membrane over the posterior part of the tongue and run forward to attaches to the mucus membrane at its edges and tip.

Shorting the tongue and turn its tip and edges upwards.

Inferior longitudinal fibers

Situated lateral to genioglossus in the lower part of the tongue.

Shorten the tongue turn its tip and edges downwards.

Vertical fibers Run from the dorsum of the tongue to the mucus membrane on its ventral surface.

Flatten and broaden the tongue.

Intrinsic muscles

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

muscle Origion and insertion Action

Genioglossus From the upper mental spine of the mandible, its fiber run posteriorly upward and downward.

Aprotracture and depressor.

Hyoglossus From the superior border of the greater horn of the hyoid bone and passes vertically upward.

Depress the tongue.

Styloglossus From the anterior surface of the styloid processes run forward downward to enter the tongue below the insertion of the palatoglossus muscle.

Retractor of the tongue.

palatoglossus From the aponeurosis of the soft palate and descends to the tongue.

Raise the tongue to narrow the oropharyngeal isthmus.

Condroglossus From the lesser cornu of the hyoid and ascending to blend with the intrinsic lingual muscle.

Extrinsic muscles

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

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

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

BLOOD SUPPLY

Arteries:

Lingual artery

Tonsillar branch of

facial artery

Ascending

pharyngeal artery

Veins:

Lingual vein,

ultimately drains into

the internal jugular

vein

Hypoglossal

nerve

Lingual

artery & vein

Deep lingual

vein

Dorsal lingual

artery & vein

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)

SPECIALIZED MUCOSA

• Covers the dorsum of the tongue.

• Occupies 15% of the oral cavity.

• Although it is masticatory mucosa by function but due to its high extensibility and lingual papillae, it is classified as

• “SPECIALIZED MUCOSA”.

Lingual Papillae:

These are the small nipple or hair–like structures on the upper surface of the

tongue that give the tongue its characteristic rough texture.

Four types of papillae are found on dorsum of the tongue:

1. Fungiform papillae

2. Filiform papillae

3. Foliate papillae

4. Circumvallate papillae

• Fungiform

Papillae:

fungus-like appearance

present on tip and sides of

tongue

scattered between filiform

papillae

smooth, rounded structures

covered by non-keratinized

epithelium

Appear red due to highly

vascular CT

Taste buds are present on the

superior surface

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Fungiform Papillae

• Filiform Papillae

Hair-like appearance

Cover entire anterior part of

tongue

Cone-shaped structures

covered by thick keratinized

epithelium

Form a tough surface

involved in compressing and

breaking food when tongue is

apposed to hard palate

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Filliform Papillae

• Foliate Papillae

Leaf-like appearance

Present on lateral margins of posterior part of tongue

Consist of parallel ridges that alternate with deep grooves in the mucosa

A few taste buds are present in their lateral walls

Circumvallate papillae Arranged anterior to sulcus terminalis 8-12

in number

Large structures surrounded by a deep, circular groove into which ducts of minor salivary glands (Glands of Ebner) open

Covered by keratinized epithelium on superior surface and non-keratinized epithelium on lateral surface

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Circumvallate Papilla and Taste buds (arrows)

TASTE BUDS

GINGIVA

Consists of dense vascular fibrous tissue which is covered by

mucuos membrane and attached to the alveolar margins of the

jaws.

Dorsal tongue. (a) The dorsal surface of the tongue is

covered by specialized mucosa. The roughness of the surface is

attributable to the abundant, small hair-like filiform papillae

that cover much of the anterior two- thirds of the tongue, and

lack taste buds. The less numerous, small, round, white-red,

papular fungiform papillae are distributed over the dorsal

surface (center of grey circles). On the most posterior one

third of the oral portion of the tongue are the 8 to 12 large

circumvallate papillae (arrows) that are lined up in a V-

formation and converge at the foramen cecum. (b) This view of

the dorsal tongue demonstrates the arrangement of

circumvallate papillae in a V-shaped configuration at the

junction of the anterior two-thirds and the posterior one-third

(arrows). (c) Taste buds (arrows) are present in the epithelium

of the lateral surfaces of the circumvallate papilla. (d) An

individual taste bud within the epithelium of the papillary

trough. The orifice (taste pore) (arrow) of the taste bud opens

into the lateral wall of the circumvallate papilla, allowing for

taste sensation to be received by the taste bud.

http://pocketdentistry.com/9-oral-mucosa-and-mucosal-sensation

SOFT PALATE

Attached to the posterior border of the hard palate

Covered on its upper and lower surfaces by mucous

membrane (Palatine Aponeurosis)

Composed of:

Muscle fibers

An aponeurosis

Lymphoid tissue

Glands

Blood vessels

Nerves

PALATINE APONEUROSIS Fibrous sheath

Attached to posterior border of hard palate

Is expanded tendon of tensor velli palatini

Splits to enclose musculus uvulae

Gives origin & insertion to palatine muscles

1. Uvula is the median conical projection marked by median raphe.

2. Palatine arches are free margins of the soft palate and splitting into two parts as they approach the lateral wall.

a. Palatoglossal arch or anterior pillar of fauces or anterior palatine arch encloses the palatoglossus muscle.

b. Palatapharyngeal arch or posterior pillar of fauces or posterior palatine arch encloses the palatopharyngeus muscle.

MUSCLES

Tensor veli palatini Origin: spine of sphenoid;

auditory tube

Insertion: forms palatine aponeurosis

Action: Tenses soft palate

Levator veli palatini Origin:petrous temporal bone,

auditory tube, palatine aponeurosis

Insertion: palatine aponeurosis

Action: Raises soft palate

Musculus uvulae Origin: posterior border of hard

palate

Insertion: mucosa of uvula

Action: Elevates uvula

MUSCLES

Palatoglossus

Origin: oral surface of

palatine aponeurosis

Insertion: side of tongue at

the junction of oral and

pharyngeal parts

Action: pulls root of tongue

upward, closes

oropharyngeal isthmus

Palatopharyngeus Origin: Ant Fasciculus-Post border of hard palate Post fasciculus-palatine aponeurosis

Insertion: posterior border of thyroid cartilage,

wall of the pharynx and its median raphe.

Action: Elevates wall of the pharynx

Non-Ketratinized stratified epith.

SENSORY NERVE SUPPLY Mostly by the maxillary nerve through its branches:

Greater palatine nerve

Lesser palatine nerve

Nasopalatine nerve

Glossopharyngeal nerve supplies the region of the soft palate

MOTOR NERVE SUPPLY

All the muscles, except tensor veli palatini, are

supplied by the:

Pharyngeal plexus

Tensor veli palatini supplied by the:

Nerve to medial pterygoid, a branch of

the mandibular division of the

trigeminal nerve

BLOOD SUPPLY

Branches of the

maxillary artery

Greater palatine

Lesser palatine

Sphenopalatine

Ascending palatine,

branch of the facial

artery

Ascending pharyngeal,

branch of the external

carotid artery