ORAL MUCOUS MEMBRANE

• Oral mucous membrane


  Oral mucosa
• Mucous Membrane


  • The moist lining of the oral cavity that is in continuation with the exterior surface of skin on one end & esophagus on the other end
  • Stomatitis (inflammation of the mucosa)
• Functions of oral mucosa

  • Protection: Barrier for mechanical trauma and microbiological insults
  • Sensation: Temperature (heat and cold), touch, pain, taste buds, thirst; reflexes such as swallowing, etching, gagging and salivating
  • Secretion: Salivary secretion
• Organization of Oral mucosa (by function)

  • Masticatory Mucosa
  • Lining Mucosa
  • Specialized Mucosa
• Masticatory Mucosa


  • 25% of total mucosa. Gingiva (free, attached and interdental) and hard palate.
  • Primary mucosa to be in contact with food during mastication.
  • Masticatory Mucosa is usually KERATINIZED.
• Lining Mucosa


  • 60% of total mucosa. Covers the floor of mouth, ventral (underside) tongue, alveolar mucosa, cheeks, lips and soft palate.
  • Does not function in mastication and therefore has minimal attrition.
  • Non-keratinized; soft and pliable.
• Specialized Mucosa


  • 15% of total mucosa. Covers dorsal tongue and composed of cornified epithelial papillae.
• Factors affecting color of the oral mucosa

  • Concentration and state of dilation of the blood vessels in underlying connective tissue
  • Thickness of the epithelium
  • Degree of keratinization
  • Amount of melanin pigmentation
• Clinically, color of oral mucosa is very important. For example, inflamed oral tissues appear red rather than the normal pale pink
• Histologic structure of oral mucosa

  • Epithelium
  • Connective tissue (lamina propria and submucosa)
• Epithelium


  • Keratinized
  • Non keratinized
• Connective tissue


  • Basement membrane - The interface between epithelium and connective tissue is comprised of a structureless layer
  • Rete ridges or rete pegs - downward projections of epithelium
  • Connective tissue papillae - upward projection of connective tissue
  • Epidermis and dermis
• Submucosa


  • Loose fat and glandular tissue with blood vessels and nerves seen underneath oral mucosa from underneath bone or muscle layer (flexibility)
  • Oral mucoperiosteum - firm, inelastic attachment in gingiva and hard palate, no submucosa is seen and the lamina propria is directly attached to the periosteum of the underlying bone
  • Connective tissue in oral cavity is comprised of salivary glands, sebaceous glands(Fordyce's disease) and lymphoid tissue (tonsillar tissue)
• Components of oral epithelium: Non keratinized mucosa

  • Stratum Basale:Basal cell layer comprised of cuboidal cells. Progenitor cells that divide and provide new cells by mitotic division that migrate to the surface to replace cells that are shed.
  • Stratum Spinosum (or intermedium):Cells are oval and represent bulk of the epithelium.
  • Startum Superficiale: Cells are flat and contain small oval nuclei that are continuously shed.
• Histology of the lip

  • Skin:keratinized stratified squamous epithelium with adnexal skin structures
  • Oral Mucosa: Moist-surface, covered by nonkeratinized stratified squamous epithelium associated with small round seromucous glands of the lamina propria. In the submucosa fibers of orbicularis oris muscle is noted.
  • Vermillion zone: Very thin keratinized epithelium that contains no adnexal skin structures (can contain sebaceous glands)
  • What gives it a red color? 1.Epithelium is thin

  2.Epithelium contains eleidin, which is transparent.

  3.Blood vessels are present near the surface Eleidin is a semi-fluid clear substance present in the stratum lucidum of the skin epithelium
• Histology of the soft palates

  • Non-keratinized
  • Highly vascularized so more pink than hard palate
  • Lamina propria and submucosa present (unlike hard palate when only lamina propria is noted – mucoperiosteum)
  • Submucosa contains salivary glands and muscle
• Histology of the cheeks or buccal mucosa

  • Similar to lips and soft palate
  • Non-keratinized stratified squamous epithelium, lamina propria and submucosa
  • Submucosa of cheeks contain fat cells along with lobules of minor salivary glands and muscle fibers
• Histology of the ventral surface of the tongue

  • Non-keratinized stratified squamous epithelium, lamina propria and submucosa
  • Extremely dense muscle fibers interlacing connective tissue fibers in submucosa
• Histology of the floor of the mouth

  • Non-keratinized stratified squamous epithelium, lamina propria and submucosa
  • Epithelium is loosely attached to lamina propria
  • No muscle
• Keratinized mucosa: Masticatory mucosa

  • Epithelium that covers gingiva and hard palate
  • Mucosa is thicker than non-keratinized because of the keratin layer

  a. Stratum basale

  b. Startum spinosum

  c. Stratum granulosum: Cells contain keratohyaline granules

  d. Stratum corneum: Contains thin, flat and non nucleatedcells which are filled with keratin. Keratin is tough, nonliving material that is resistant to friction and impervious to bacterial invasion
• Histology of the gingiva


  • In healthy attached gingiva "stippling"is seen which appears as small pits in the epithelium and are due to deep rete pegs.
  • The lamina propria is composed of long narrow papillae which are not highly vascular.
  • No distinct submucosa is noted as the overlying mucosa is directly attached to the underlying periosteum and cementum by collagen fibers
• Types of gingiva


  • Free Gingiva: Keratinized; NOT STIPPLED; bound on inner margin by the gingival sulcus, which separates it from the tooth; bound on its outer margin by the oral cavity; and apically by the free gingival groove.
  • Attached Gingiva: Keratinized; STIPPLED; separated from the alveolar mucosa by the mucogingival junction (groove). Attached to the tooth by junctional epithelium.
• Dentogingival junction and junctiobal

  • Dentogingival junction is the region where the oral mucosa meets the surface of the tooth

  Very important because it is a weak area in the oral mucosa which is otherwise continuous

  Bacteria on the surface of the tooth produce toxins that can incite inflammation and damage if it enters into the mucosal tissues

  Gingival sulcus in healthy individuals is ~ 0.5 to 3 mm (mild inflammation is present -1.8 mm average)

  Depth greater that 3mm is considered pathologic; and the sulcus represents periodontal pocket

  Floor of the sulcus and the epithelium cervical to it is called junctional epithelium which is in contact with the tooth surface (enamel and sometimes cementum) epithelium
• Histology of the hard palate

  • Thick orthokeratinized (or parakeratinized in areas) epithelium showing ridges (rugae)
  • Lamina propria shows long papillae with thick dense connective tissue
  • Submucosa is mucoperiosteum with dense collagenous connective tissue attaching directly to periosteum. Contains fat and salivary glands
• Oral epithelium


  Specialized mucosa
• Dorsum of the tongue

  • Filiform papilla
  • Fungiform papilla
  • Foliate Papilla
  • Circumvallate
• Filiform papilla


  1. Makes up majority of the papillae and covers the anterior part of the tongue

  2. They appear as slender, threadlike keratinized projections (~ 2 to 3 mm) of the surface epithelial cells

  3. These papillae facilitate mastication (by compressing and breaking food when tongue is apposed to the hard palate) and movement of the food on the surface of the tongue

  4. The papillae is directed towards the throat and assist in movement of food towards that direction

  5. NO TASTE BUD
• Fungiform papilla


  • (Fungus-like)
  • These are interspersed between the filiform papilla
  • More numerous near the tip of the tongue
  • Smooth, round structures that appear red because of their highly vascular connective tissue core, seen through a thin, nonkeratinized stratified squamous epithelium
  • Taste buds are usually seen within the epithelium
• Foliate Papilla


  1. (Leaf-like)

  2. Present on the lateral margins of the posterior tongue

  3. Consist of 4 to 11 parallel ridges that alternate with deep grooves in the mucosa, and a few taste buds are present in the epithelium

  4. They contain serous glands underlying the taste buds which cleanse the grooves
• Circumvallate


  1. (Walled papilla)

  2. 10 to 14 in number these are seen along the V-shaped sulcus between the base and the body of the tongue

  3. Large, ~ 3 mm in diameter with a deep surrounding groove. Ducts of von Ebner glands (serous salivary glands) open into the grooves

  4. Taste buds are seen lining the walls of the papillae
• Taste Buds


  • Unique sense organs that contain the chemical sense for taste
  • Microscopically visible barrel-shaped bodies found in the oral epithelium
  • Usually associated with papillae of the tongue (circumvallate, foliate and fungiform)
  • Also seen in soft palate, epiglottis, larynx, and pharynx. Referred to as NEUROEPITHELIAL STRUCTURES
  • Each taste bud has ~ 10 to14 cells. Majority are taste cells with elongated microvilli that project into the taste pore
• Periodontal pocket is a pathologically deepened gingival sulcus that forms due to the apical migration of attachment of epithelium generally as a reaction against bacterial toxins, plaque toxins & immunologic response
• Oral Manifestations of Systemic Disease

  • Measles – koplik spots
  • Syphilis
  • Candidiasis
  • Warts
  • herpes
  • Chicken pox
• Injections should be made into the loose submucous connective tissue
• The sebaceous glands are present as small yellow spots at various sites of oral cavity specially in cheeks. They are visible in the form of large, yellowish patches called Fordyce's spots or granules. These do not represent pathologic change but is a developmental anomaly
• Fordyce's spots


  • Pale yellow spots
  • Normal variation
  • Lips, buccal mucosa, alveolar mucosa and tonsillar pillar