oral mucous membrane Flashcards
introduction
A mucous membrane is the lining of nasal passage, gut and other body cavities.
oral mucous membrane is the moist lining of the oral cavity.
1.DIVISION-
it is divided into oral cavity proper(separated from oral vestibule by gingiva and alveolar bone)
oral vestibule(bounded by lips and cheeks)
2.PARTS-
1.superiorly
hard palate and soft palate
2.inferiorly
floor of the mouth and base of the tongue
3.posteriorly
paucial pillars and the tonsils.
3.CONTINUTY
at lips with the skin and at pharynx with the git.
4.TISSSUE COMPONENTS
EPITHELIUM-KERETINIZED AND NON KERETINIZED
CONNECTIVE TISSUE
SUBMOUCOSA
BASEMENT MEMBRANE
CLASSIFICATION OF THE MUCOSA.
the oral mucosa is classified on the basis of function and type of epithelium present .
On the basis of function-
1. Masticatory mucosa
-Present in hard palate and gingiva
-Is bounded to the bone
-Does not stretch
-bears masticatory forces
2. Lining mucosa
-present in lips,buccal,vestibular fornix, alveolar mucosa,floor of mouth, soft palate
-covers the masculature
-stretchable as it contracts and relaxes to the movement of oral cavity
3. Specialised mucosa
-present in dorsum of the tongue and taste buds
-specialised as it have a sensory function.
On the basis of location
Keretinised and non keretinised
Basement membrane
- LIGHT MICROSCOPE STRUCTURE
-The epithelium and the connective tissue is separated by a structure, which one light microscope is called as basement membrane.
-The interface between epithelium and connective tissue appears thick and include reticular fibres and is cell free.
-this zone stains positive with acid schiff method indicating the presence of GAGS - ULTRASTRUCTURALLY
-Is called basal lamina
-is made of two zones
Clear zone( lamina lucida)
Dark zone(lamina densa)
Fibroreticularis
-lamina lucida is a glycoprotein layer
-have collagen4
-have laminin and bull-ous pemp-hi-goid
-lamina densa have collagen 4 coated with heparin sulfate and have chicken wire configuration.
-adjacent to connective tissue and beyond lamina lucida, we have ANCHORING FIBRES
-have collagen7 which form loops and r inserted to lamina densa
-collagen 1&2 run through th se loops
The basement membrane promote-
-differentiation
-peripheral nerve regeneration
-prevent metastases
Functions of oral mucosa
- Defense
-microorganisms that normally reside within the oral cavity would cause
infection if they gained access to the tissues.
-Many of these organisms
also produce substances that have a toxic effect on tissues.
-The
epithelium of the oral mucosa acts as the major barrier to these threats.
-It also secrete antibodies and has efficient humoral and cell mediated immunity
- Protection
-As a surface lining, the oral mucosa separates and protects deeper tissues
and organs in the oral region from the environment of the oral cavity.
-The normal activities of seizing food and biting and chewing expose the
oral soft tissues to mechanical forces (compression, stretching, and
shearing) and surface abrasions (from hard particles in the diet).
- The oral
mucosa shows a number of adaptations of the epithelium and the
connective
tissue
to
withstand
these
insults.
- Lubrication
- the secretions of salivary gland keeps the oral cavity moist and thus prevent the mucosa from drying and cracking
- the moist oral cavity helps in speech, mastication, swallowing, perception of taste
- Sensory
The oral mucosa is sensitive to touch, pressure, pain, temperature
-the sensitivity varies in different areas
- generally these are better appreciated in anterior part of the mouth
- the sensation of taste is a unique, only felt in anterior 2/3rd of the dorsum of the tongue 👅
-swallowing, gagging, retching, salivating reflexes are initiated
By receptors of oral mucosa
- Thermal regulation
-In some animals (such as the dog), considerable body heat is dissipated
through the oral mucosa by panting; for these animals the mucosa plays
a major role in the regulation of body temperature.
-The human oral
mucosa, however, plays practically no role in regulating body
temperature, and no obvious specializations of the blood vessels exist for
controlling heat transfer.
Comparison of oral mucosa of skin, oral, intestine
- Oral mucosa - epithelium, connective tissue
Skin- dermis , epidermis
Intestine- epithelium , lamina propria - Extra layer
Intestine- muscularis mucosa (between lamina propria and submucosa)
Skin-stratum lucidum - Skin is always ortho keretinised
While the oral part can be ortho/para / non - Skin appendages like hair follicles, sebaceous glands, sweat glands r nt present in oral
Similarly salivary gland r not present in skin
Lamina propria
- What
It can be described as connective tissue of variable thickness that supports the epithelium. - It’s divided into two parts
-papillary
-reticular part
the two portions are continuous. - Papillary part
-present between epithelial ridges
-may be absent in some areas like alveolar mucosa. - Reticular part
-present below epithelial ridges
-contain fine argyrophilic reticular fibres
-net like arrangement of collagen fibrils
-it is always present - -The papillae of connective tissue protrude towards the epithelium carrying blood vessels and nerves.
-the epithelium does not contain blood vessels.
-the epithelium in turn is formed into ridges that protrude towards the lamina propria
-these ridges interdigitate with the papilla and are called called epithelial ridges
-under microscope these ridges are look like pegs
-this interlocking arrangement increase the surface area of contact between the lamina propria and epithelium
And facilities exchange of material .
- Contents of lamina propria
Book table - Ground substance -
- Cells-
- Blood vessels and nerves
Submucosa
- Attaches the mucous membrane to underlying structure
Whether this attachment is loose or firm depend upon the characteristics of submucosa - Contents
-salivary glands
-blood vessels
-nerves
-adipose tissue
3.
-In submucosa the larger arteries divide into smaller when they enter lamina propria
- they divided again to form SUBEPITHELIAL CAPILLARY NETWORK in the papilla
- the veins originate from the capillary network and course back
- the blood vessels are accompanied by lymph vessels and non myelinated visceral nerve fibres that supply smooth muscle and glands
-the nerve fibres are myelinated , but lose their myelin sheath before splitting
Nerve ends are surrounding by schwann cells
-sensory nerves are more concentrated in anterior part of the mouth
-Specialised receptors
Kra-use end bulbs(COLD)
mei-ss-ner corpuscles (touch)
free nerve endings (pain)
Mechanoreceptors
Keretinised areas-
Masticatory mucosa
-They masticatory mucosa is keretinised and is made up of gingiva and hard palate.
-it is moderately thick
-it is commonly ortho keretinised
-The junction between epithelium and underlying lamina
propria is convoluted, and the numerous elongated papillae probably
provide good mechanical attachment and prevent the epithelium from
being stripped off under shear force
The lamina propria is thick,
containing a dense network of collagen fibers in the form of large, closely
packed bundles., enabling the
mucosa to resist heavy loading
Masticatory mucosa covers immobile structures (e.g., the palate and
alveolar processes) and is bound firmly to them directly by the
attachment of lamina propria to the periosteum of underlying bone, such
as in mucoperiosteum, or indirectly by a fibrous submucosa
In the
lateral regions of the palate, this fibrous submucosa is interspersed with
areas of fat and glandular tissue that cushion the mucosa against
mechanical loads and protect the underlying nerves and blood vessels of
the palate.
Hard palate
1.HARD PALATE-
- The mucous membrane is tightly fixed to the underlying periosteum and therefore immovable.
-The epithelium is uniform and well keretinised,
there is a increase in number and length of desmosomes, density of tonofilaments and complementary grooves and ridges
all appear to be adaptations of keretinised epithelium to resist forces and to bind the epithelium to connective tissue.
-The lamina propria is
thicker in anterior than posterior parts of the palate and has numerous long papilla.
-
submucosa
Extends- between palatine gingiva and palatine raphe
Attached immovably to the- periosteum of maxillary and palatine bones,
this attachment is formed by dense bands and trabecular that joins the lamina propria to periosteum
-The submucosa space consists of adipose tissue in anterior part and glands in posterior parts, they act as a cushion .
- At the junction of the alveolar process and the horizontal plate of the hard palate
, the anterior palatine vessels and nerve course and are surrounded by loose connective tissue
this wedge shape area is large in the posterior part of the palette and smaller in the anterior part.
PARTS
Incisive Papilla
-It is formed of dense connective tissue
-it contains the oral parts of the
vestigial nasopalatine ducts.
- they are blind ducts,
- lined by simple or pseudostratified columnar epithelium
- rich in goblet cells
-Small mucus glands open into the lumen of these ducts
Which sometimes became cystic in humans
-In most mammals the naso palatine ducts are patent and together with jacobsons organ(small ellipsoid organ which extends from nose to the oral cavity) are considered as auxiliary olfactory sense organs
-palatine rugae
-Irregular asymmetric in human
They are ridges of mucus membrane that extends literally from the incessive papilla and the anterior part of the raphe
-There core is made up of dense connective tissue layer with fine interwoven fibers.
Epithelial pearls
They are the remnants of the epithelium formed in the line of fusion between the palatine process
Present in the region of incessive papilla and can also be found in lamina propria.
Consists of concentrically arranged epithelial cells that are frequently keretinised.
Gingiva
GINGIVA
75% para keretinised
15% keretinised
10% non keretinised (col)
-Extends - DEJ to alveolar mucosa
-subjected to. - friction and pressure of mastication
The morphology of epithelium and connective tissue indicates the adaptation to these forces
Colour
-pink/reddish due to underlying blood vessels and circulating blood
Can also be a Greyish tint.
-depend on
- the surface
(keretinised or not)
(Translucent/transparent)
-And pigmentation
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MICRO ANATOMY
-epithelium
-can be keretinised/non keretinised
-often para keretinised
-LAMINA PROPRIA
-dense
-collagen fibres insert into the alveolar bone and the cementum/blend with periosteum.
-
Division of collagen fibrils
1. Dentogingival
(Extends from cervical cementum into the lamina propria, most numerous)
2. Alveologingival
(The fibres arise from alveolar crest and extent to lamina propria)
3. Circular
(A small group of fibres that circle around the tooth and interlase with other fibres)
4. Dentoperiosteal
(Follows from cementum to periosteum of alveolar crest and of vestibular and oral surface of alveolar bone)
Others
-interdental
(Connect buccal and lingual papillae )
-semicircular
(Connect cementum on one to opposite side )
-longitudinal
(That run longitudinally)
-vertical
(Run coronally from alveolar mucosa/attached gingiva to free/interdental)
-transgingival
(Pass from cementum of one tooth to marginal gingiva to adjacent teeth merging with circular and semicircular)
-smallest number of plasma, macrophages, lymphocytes
Which are involved indefense and repair
-papillae are long slender and numerous
-few elastic fibres
- gingival fibres which attaches the gingiva to the tooth and periosteum of alveolar bone (mucoperiosteum)
Submucosa has the thickest elastic fibres
Limited on outer surface by mucogingival junction which separates it from alveolar mucosa.
It is identified as the junction between bright pink alveolar mucosa and pale pink 🩷gingiva
Inner surface of lower jaw we have a demarcation between gingiva and floor of mouth
Alveolar mucosa
-red
-contains small vessels
_______________________________________
MARCO ANATOMY
-free(which is the coronal most portion of gingiva)
-attached
( portion of gingiva that is attached to the underlying bone/tooth)
- shows A surface that appears stippled.
Portions of epithelial appear elevated and there r shallow depressions(rete ridges), as a net result of which is stippling - They are functional adaptation to mechanical impacts
- The disappearance of stippling is an indication of edema
- Males have more heavily stippled gingiva
-interdental papilla(the gingiva appears slightly depressed between the adjacent teeth,
in these depressions the gingiva sometimes from a vertical fold called the interdental grooves or papilla)
-it is pyramidal in shape and in POSTERIOR teeth it is 🎪 shape.
COL
- connect buccal and lingual side of interdental papilla
- the depressed part of interdental papilla
- occupies the area below the contact point
- Covered by thin non keretinised epithelium
- therefore is More vulnerable to periodontal disease.
Free gingival groove
-division line between free and attached gingiva
-develops at the level of gingival sulcus
-caused due to functional impact on gingiva
-in the absence of gingival sulcus there is no free gingiva
gingival sulcus
- it is the space between inner aspect of gingiva and the tooth
- extends: free gingiva to DEJ
- In a healthy state, it’s depth is approximately leve of free gingival groove, The average sulcus is 1.8m to 2mm
It’s depth increase with periodontal disease (periodontal pocket)
- The sulcus may be responsible for the formation of the groove since it leaves the gingival margin without firm support
- The sulcular epithelium is non keretinised in humans
-lacks epithelial ridges
- it express CK4 which is a typical lining epithelium
- it is continuous with gingival epithelium and attachment epithelium.
Arterial supply of oral mucosa
Arterial Blood Supply to the Oral Mucosa
Upper lip - Superior labial artery(anastomoses with buccal artery)
Upper gingiva-
- Anterior
Anterior superior alveolar artery - Lingual
palatine artery - Buccal
Buccal artery - Posterior
Posterior superior alveolar artery
Lower gingiva-
Anterior buccal-
Mental artery
Anterior lingual
- Incisive artery and
sublingual artery
Posterior lingual
- Inferior alveolar artery and sublingual artery
Posterior buccal
- Inferior alveolar artery and buccal artery
Hard palate
-palatine artery
- Nasopalatine artery
-Sphenopalatine artery
Soft palate
palatine artery
Cheek
-Buccal artery
-Some terminal branches of facial artery
-
Posterior alveolar artery
-Infraorbital artery
Lower lip
-Inferior labial artery
(anastomoses with buccal artery)
-Mental artery
-Branch of inferior alveolar artery
Floor of mouth
-Sublingual artery
Tongue (dorsal and ventral surfaces)
-Anterior two thirds
-
Deep lingual artery
Posterior third
Dorsal lingual artery
Nerve supply of the oral mucosa
- Upper lip and
vestibule
-Twigs from infraorbital branch of maxillary nerve
2.Upper gingiva
Anterior, posterior, and (when present) middle superior alveolar branches of
maxillary nerve
3.Hard palate
Greater, lesser, and sphenopalatine branches of maxillary nerve
4.Soft palate
-Lesser palatine branch of maxillary nerve,
-
tonsillar branch of glossopharyngeal
nerve, - nerve of pterygoid canal (taste; originating from facial nerve)
- Cheek
-Twigs from infraorbital branch of maxillary nerve,
- superior alveolar branch of
maxillary nerve,
-buccal branch of mandibular nerve, -terminal
branches of facial nerve
6.Lower lip and
vestibule
-Mental branch of inferior alveolar nerve
-buccal branch of mandibular nerve
7.Lower gingivae:
buccal
Inferior alveolar branch of mandibular nerve, buccal branch of mandibular
nerve, and sublingual branch lingual of lingual nerve
Anterior two
thirds of tongue
Lingual branch of mandibular nerve (taste provided by fibers carried in lingual
nerve but originating in facial nerve and passing by way of chorda tympani to
the lingual nerve
Posterior third of
tongue, facial, and
tonsillar
Glossopharyngeal nerve (taste and general sensation)
Vermillion zone
- The transitional zone between the skin of the lip and the mucous membrane of lip is vermillion zone
-it is also called red zone
-a line that separates the skin from the vermillion zone is called vermillion border
-the vermillion border of the upper lip is arched and if referred to cupid bow
-The junction of the upper lip/lower lip vermillion border is called a commissure
Present at the corner of the mouth
-they skin on the outer surface of lip is of moderately thick keretinised epithelium.
The blood is visible through the thin parts of keretinised epithelium and gives red colour to the lips
The kertnisation decrease towards the lip but thickness of epithelium increases
The inner aspect of lip is the thicker non keretinised labial mucosa
-The papilla of the connective tissue are few and short
Have many sabeccous gland with few connections to hair follicles and sweat glands between them.
- **The transitional area is exposed to atmosphere and has no glands to keep it moisturized therefore the lips becomes easily dried and we lick to moisten it.
Linning mucosa
The lining mucosa is found on the lips
cheeks
vestibular fornix,
and alveolar mucosa.
They have
Thick- non keretinised epithelium
Thin- lamina propria
The submucosa is loosely textured
The reflectory mucosa is found in the vestibular fornix and in sublingual sulcus at the floor of the oral cavity
Mucus membrane
is movable
attached to the deep structures and does not restrict the movement of the lips cheeks and tongue
.
As it
Is fixed to the fascia /epimysium, in these regions the mucosa is highly elastic.
these two characteristics permit the mucosa to maintain a relatively smooth surface during muscular movement
thus, heavy folding which could lead to injury during chewing if such folds were got between the teeth.
Soft palate
Mucous membrane -
highly vascularized
Reddish color
Papilla of connective tissue -
Few
Short
Epithelium-
Stratified squamous epithelium
Non keretinised
Lamina propria -
Has distinct layer of elastic fibres separating it from submucosa
Submucosa-
Loose
Has continuous layer of mucous glands
Contain taste buds
Typical oral mucosa continuous around the free border of the soft palette for a variable distance and is then replaced by nasal mucosa with its psudo stratified cilliated columnar epithelium
