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Understanding the Oral Mucous Membrane

Mar 24, 2025

Lecture Notes: Oral Mucous Membrane (OMM)

Introduction

  • Welcome to Easy Dentistry
  • Topic today: Oral Mucous Membrane (OMM)
  • Structure of lecture: Four parts
    1. Basics of OMM
    2. Non-keratinized epithelium
    3. Keratinized epithelium
    4. Gingival sulcus and dento-gingival junction
  • Importance of topic for exams

Basics of Oral Mucous Membrane

  • Classification of OMM based on function:

    • Masticatory Mucosa (60%): Hard palate and gingiva
    • Lining Mucosa (25%): Lip, cheek, vestibule, floor of mouth, alveolar mucosa, soft palate
    • Specialized Mucosa (15%): Dorsum of tongue and taste buds

  • Two structures in OMM:

    • Dento-gingival junction
    • Vermilion border of lip

Types of Oral Mucous Membrane

  • Keratinized Mucosa:
    • Includes masticatory mucosa and vermilion border
  • Non-Keratinized Mucosa:
    • Includes lining mucosa and specialized mucosa

Functions of Oral Mucous Membrane

  1. Defense: Prevents entry of microorganisms/toxins
  2. Lubrication: Saliva from minor salivary glands keeps mucous membrane moist
  3. Sensory: Sensitive to touch, pressure, pain, and temperature
  4. Protection: Protects deeper tissues from mechanical trauma

Structure of Oral Mucous Membrane

  • Four layers of OMM:
    1. Epithelium
    2. Lamina Propria (connective tissue)
    3. Submucosa (loose connective tissue)
    4. Underlying tissues (bone/muscle)

Epithelium

  • Types: Keratinized or non-keratinized (orthokeratinization or parakeratinization)

Lamina Propria

  • Contains salivary glands
  • Divided into:
    • Papillary Part: Just below the epithelium
    • Reticular Part: Always present

Submucosa

  • Connects upper structures to underlying tissues
  • Contains glands, blood vessels, collagen fibers, adipose tissue, nerves

Comparison of Mucous Membranes

  • Oral Mucosa: 4 layers
  • Skin: 3 layers (epidermis, dermis, no submucosa)
  • Intestinal Mucosa: 5 layers (includes muscularis mucosa)

Interface Between Epithelium and Lamina Propria

  • Corrugated Appearance: Ridges (from epithelium) fitting into papillae (from connective tissue)
  • Known as serpentine appearance
  • Basement Membrane: 1-4 micrometers thick, rich in mucopolysaccharides

Basement Membrane Structure

  • Light Microscope: Known as basement membrane
  • Electron Microscope: Called basal lamina, has:
    • Lamina Lucida: Adjacent to epithelium, 20-40 mm, contains type 4 collagen
    • Lamina Densa: Below lamina lucida
  • Anchoring Fibrils: Made of type 7 collagen

Summary of Lamina Propria and Submucosa

  • Lamina Propria: Dense fibrous connective tissue with type 1 and type 3 collagen
  • Submucosa: Loose connective tissue varying in thickness, connects to underlying tissues

Important Points to Note

  1. Type of epithelium (keratinized/non-keratinized)
  2. Thickness of epithelium
  3. Characteristics of lamina propria
  4. Junction between epithelium and lamina propria
  5. Condition of submucosa

Quiz Questions

  1. What percentage of the oral mucous membrane is covered by masticatory mucosa?
  2. Which type of collagen is found in anchoring fibrils?
  3. Which layer is absent in oral epithelium but present in intestinal epithelium?

Conclusion

  • Importance of understanding OMM basics for upcoming lectures
  • Reminder to subscribe to the channel for more updates.

Full transcript