Types of Oral MucosaBy: Abdullah Akbar

Madeeha Jamil

Oral mucosa

Oral mucosa is the moist lining of the oral cavity.

COMMUNICATIONS:

- Anteriorly it is continuous with the skin of the lip through

vermilion border.

- Posteriorly it is continuous with the mucosa of the pharynx.

Anatomically it is located between the skin and GIT mucosa.

Types of oral mucosa

On the basis of structural and functional variations in different areas of the

oral cavity, oral mucosa is classified into:

1. Masticatory mucosa

2. Lining mucosa

3. Specialized mucosa

Masticatory Mucosa

Covers those areas of the oral cavity such as hard palate and gingiva, that

are exposed to masticatory forces.

Occupies almost 25% of the oral cavity.

Epithelium:

- Moderately thick

- Mostly orthokeratinized though areas of parakeratinization may be seen.

- Epithelial surface is inextensible.

Masticatory mucosa

Lamina Propria:

- Thick

- Contains closely packed bundles of collagen fibers

- Collagen fibers follow a regular course between anchoring point enabling the mucosa to resist heavy loading.

Interface between epithelium and lamina propria:

- Convoluted junction

- Numerous elongated CT papillae are present which provide good mechanical attachment and prevent the epithelium from being stripped off

under shear forces.

Masticatory mucosa

Submucosa:

- Present in fatty zone and glandular zone of hard palate

- Absent in gingiva, palatine raphe and part of hard palate adjacent to

gingiva

Masticatory mucosa

Lining mucosa

Covers the under surface of tongue, floor of mouth, inside of lips & cheeks,

alveolar processes and soft palate.

Occupies 60% of the oral cavity

Epithelium:

- Usually thin but Thicker than that of masticatory mucosa in

cheeks.

- Non-keratinized in under surface of tongue, floor of mouth, cheeks,

alveolar process and soft palate.

- Orthokeratinized in vermilion zone and parakeratinized in intermediate

zone of lips.

Lining Mucosa

Linea alba is a slight whitish ridge that occurs along the buccal mucosa in

occlusal plane. It is a region of keratinization.

Lining mucosa

Lamina Propria:

- Usually thicker than that of masticatory mucosa.

- Contains fewer collagen fibers which follow irregular course between

anchoring points making the mucosa stretchable to certain extent.

- Also contains elastic fibers which control the extensibility of the mucosa.

Interface between epithelium and lamina propria:

- Smooth junction

- Short CT papillae are found in soft palate, underside of tongue, floor of

mouth and alveolar processes.

- Elongated papillae are present in labial and buccal mucosa.

Lining Mucosa

Lining Mucosa

Submucosa is generally present in lining mucosa

Where lining mucosa covers muscles, it is attached by a mixture of collagen

and elastic fibers

As mucosa becomes slack during mastication, elastic fibers retract mucosa

towards the muscle and prevents the mucosa from being bitten

Lining mucosa

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”.

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

Specialized mucosa

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

Specialized mucosa

Fungiform papillae

Specialized mucosa

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

Specialized mucosa

Filiform papillae

Specialized mucosa

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

Specialized mucosa

Foliate papillae

Specialized mucosa

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

Specialized mucosa

Circumvallate papillae

Clinical considerations

Lining mucosa is soft and pliable; gingiva and hard palate are covered by

immobile layer.

Local injections: fluid can be introduced easily into lining mucosa. Injection

into masticatory mucosa is difficult and painful.

Clinical considerations

Biopsy/wounds: Lining mucosa gapes and requires suturing; masticatory

mucosa does not.

Inflammation: accumulation of fluid is painful in masticatory mucosa; in

lining mucosa the fluid disperses and inflammation is not that evident or

painful.

Clinical considerations

Hairy tongue: buildup of keratin on filiform papillae results in their

elongation, giving the dorsum of tongue a hairy appearance.

Black discoloration is due to pigment producing bacteria and staining from

food.