Oral Mucous Membrane

1.Oral Mucosa

The moist lining of the oral cavity is called Oral Mucosa or OralMucous Membrane

The function of oral mucosa is protection, sensation and secretion

It is continuous with the skin outside the oral cavity and differsfrom it in appearance and structure

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Oral Mucous Membrane

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Oral Mucous Membrane

Epithelium

Lamina Propria

Submucosa

Periosteum

Bone

Oral Epithelium

Oral epithelium forms the surface of the oral mucosa that forms abarrier between the oral environment and the deeper tissues

It is derived from the embryonic ectoderm

It is stratified squamous epithelium and may or may not bekeratinized

Beneath the epithelium lies the connective tissue

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Oral Epithelium

-Keratinized

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Keratinized oral epithelium

Most of the oral mucosal surface is lined by nonkeratinizedstratified squamous epithelium except gingiva, hard palate anddorsal surface of the tongue where the epithelium is keratinized

The keratinized cells have no nuclei and the cytoplasm is displacedby large numbers of keratin filaments

Keratinized epithelium is associated with masticatory function andhave four layers of cells

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

The four layers are:

1. Stratum Basale

2. Stratum Spinosum

3. Stratum Granulosum

4. Stratum Corneum

Cellular layers of oral epithelium - Keratinized

1. Stratum Basale

The cells of the stratum basale are cuboidal or low columnar andform a single layer resting on the basal lamina

The basal lamina is at the interface of the epithelium and laminapropria

Epithelial cells of the oral mucosa are in a constant state of renewal

The basal cells show the maximum mitotic activity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

2. Stratum Spinosum

Stratum spinosum is usually several cells thick

They shaped like polyhedron with short cytoplasmic processes

The stratum basale and the first layers of stratum spinosum arereferred to as stratum germinativum because these cells giverise to new epithelial cells

3. Stratum Granulosum

Cells of stratum granulosum are flat and are found in layers ofthree to five cells thick

This layer is prominent in keratinized epithelium (and absent innonkeratinized epithelium)

These cells have keratohyaline granules in their cytoplasm

Keratohyaline granules help to form the matrix of the keratin fibresfound in the superficial layer

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

4. Stratum Corneum

Cells of stratum corneum are flat, devoid of nuclei and full ofkeratin filament surrounded by a matrix

These cells are continuously being sloughed and are replaced byepithelial cells that migrate from the underlying layers

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Nonkeratinized oral epithelium

Nonkeratinized epithelial cells in the superfecial layers do not havekeratin filaments in the cytoplasm

The surface cells also have nuclei

The stratum corneum and stratum granulosum layers are absent

This epithelium is associated with lining of the oral cavity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Connective tissue

Connective tissue can be differentiated as Lamina Propria andSubmucosa

Lamina propria

Lamina propria is the connective tissue layer immediately belowthe epithelium

It can be divided into papillary layer and the reticular layer

Papillary layer forms finger like projections of connective tissuethat extend deep in the epithelial layers

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Papillary layer is prominent in masticatory mucosa and reticularlayer is prominent in lining mucosa

Lamina prorpria consists of blood vessels and cells like fibroblasts,cells of blood vessels and lymphatics and nerves

Epithelium is avascular, hence its metabolic needs come via thevessels of the lamina propria

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Submucosa

Submucosa lies below the lamina propria and serves as anattachment between lamina propria and bone or skeletal muscle

It is found in the cheeks, lips and parts of the palate

It consists of large blood vessels, nerves and lymphatics and itsfunctions are nutrition and defense

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

2. Functional types of Oral Mucosa

Lining mucosa and Masticatory mucosa

Lining mucosa

Lining mucosa covers all soft tissue of the oral cavity except thegingiva, hard palate and the dorsal surface of the tongue

Lip

Lip is covered by lining mucosa

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Lip with skin on outer surface and

lining mucosa on inner surface

Vermilion border

The junction between the skin and mucous membrane is known asthe vermilion border

Here the epithelium is thin therefore, the red blood cells in thecapillaries show through contributing to the vermilion colour D

r.Sye

dS

adatu

llahK

ing

Kh

alid U

nive

rsity

Vermelion Zone

Ventral surface of the tongue

The lining mucosa here contains both lamina propria andsubmucosa

The submucosa merges with the muscle bundles of the ventralsurface of the tongue D

r.Sye

dS

adatu

llahK

ing

Kh

alid U

nive

rsity

Ventral surface of tongue

Cheek

In the cheek the underlying submucosa contains fat cells and smallmixed salivary glands

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Cheek

Floor of the mouth

The mucous membrane of the floor of the mouth is thin andloosely attached to the underlying structures

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Floor of the mouth

Masticatory mucosa

Masticatory mucosa covers the gingiva and hard palateIn edentulous mouth, masticatory mucosa covers the chewingsurface of the dental arches

Gingiva

Gingiva has keratinized or parakeratinzed epithelium with nosubmucosal layerIt develops from the union of oral epithelium and reduced enamelepithelium of the developing toothGingiva can be classified as free gingiva, attached gingiva andinterdental papilla

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Normal Gingiva

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Development of gingiva from oral epithelium and reduced enamel epithelium

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Anatomy of gingiva

Free gingiva (or marginal gingiva)

It is that part of the oral mucosa that surrounds the necks of theteeth and forms the free margin of the gingival tissue

It is differentiated apically from the attached gingival by the freegingival groove

The inner side of it forms the gingival sulcus

The free gingival mucosa is composed of stratified squamousepithelium that may be keratinized, parakeratinzed or sometimesnonkeratinized

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Free gingiva

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Alveolar Mucosa (Arrows - Interdental Papillae)

Attached gingiva

The attached gingiva lies between the free gingival groove and thealveolar mucosa

The junction of the attached gingiva and the alveolar mucosa iscalled mucogingival junction

In healthy mouth attached gingiva shows stippling (orange-peelappearance) which is a characteristic of this type of mucosa

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Histology of gingiva

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Mucogingival junction (arrows)

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Alveolar Mucosa

Interdental papilla

Interdental papillae are those parts of gingival tissue that appearin-between teeth apical to the contact points

Interdental grooves extend vertically between the interdentalpapilla corresponding to the depressions between the roots

Confirming to the shape of the interproximal contact area is avalley like depression in the interdental papilla called Col.

This depression lies in the facial and lingual plane

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Interdental Papilla (arrow)

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Diagram of positional relation of col in health

and disease for canine, premolar and molar

Col accentuated during inflammation (arrows)

Junctional epithelium

Junctional epithelium forms the seal of the gingival epithelium andthe tooth

It forms the floor of the gingival sulcus and extends apically to theenamel of the tooth

Disturbances of epithelial attachment results in deepening of thesulcus which is a sign of gingival/periodontal disease

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Histology of gingiva

Hard palate

The surface of the hard palate that is visible in the mouth is coveredby masticatory mucosa

The lateral regions of the posterior part contains palatine glandsThese glands are purely mucous glands

The midline of the hard palate is called median raphe where thereis no submucosa

A series of folds appear in the anterior part of the palate calledrugae

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Hard Palate and Soft Palate

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Palatal rugae (arrow)

3 Mucosa of the Tongue

Specialized mucosa covers the dorsal surface of the body of thetongue

The connective tissue binds the epithelium to the underlyingskeletal muscle

The epithelium is modified, keratinized, stratified covered withpapillae, which can be seen by naked eye

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

The different papillae found on the dorsal surface of the tongue are:1. Filliform papillae

2. Funginform papillae

3. Circumvallate papillae

4. Foliate papillae

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dorsum of Tongue

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Cross section of tongue

1. Filliform papillae

Filliform papillae are pointed extensions of the keratinizedepithelial cells

They are the most numerous papillae of the tongue

They are not associated with taste buds

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Scanning electron micrograph of

Filliform papillae(arrow)

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Filliform Papillae

2. Fungiform papillae

Fungiform papillae are fewer than the filliform papillae and arescattered over the dorsal surface of the tongue

They are rounded elevations above the surface of the tongue

They have taste buds on their superior surfaces

The surface of fungiform papillae is not keratinized

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Scanning electron micrograph of Fungiform

papillae (arrow) surrounded by Filliform papillae

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Fungiform Papillae

3. Circumvallate papillae

The circumvallate papillae are located at the junction of theanterior two thirds (body) and posterior one thirds (base) of thetongue

There are eight to twelve in number and are bigger than fungiformpapillae

Circumvallate papillae are lined with taste buds and also openingsof serous glands

The secretion from the serous glands washes away food for renewalof taste

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity

Circumvallate Papilla and Taste buds (arrows)

4. Foliate papillae

Foliate papillae are located in the furrows along the posterior sidesof the tongue

They may be lined with taste buds

They are not prominent in human beings

Dr.S

yed

Sad

atullah

Kin

g K

halid

Un

iversity