Oral Mucosa: Structure and Function

Oral Mucosa: Structure and Function

The oral mucosa is the inner lining of the oral cavity, playing a crucial role in protection, mastication, swallowing, and speech. It is composed of two main layers: epithelium and connective tissue.

1. Epithelium:

– The outermost layer that directly contacts the external environment.

– Can be stratified squamous keratinized epithelium, stratified squamous parakeratinized epithelium, or stratified squamous non-keratinized epithelium, depending on the location and function of the mucosa.

a. Stratified Squamous Keratinized Epithelium:

– Found in the masticatory mucosa (hard palate, gingiva) and specialized mucosa (some areas on the dorsal surface of the tongue).

– Has 4 cell layers: basal layer, spinous layer, granular layer, and horny layer.

– The horny layer contains dead cells, keratinized, and devoid of nuclei.

– Function: Mechanical protection, resistance to friction and injury.

b. Stratified Squamous Parakeratinized Epithelium:

– Found in some areas of the gingiva and tongue.

– Has 4 cell layers similar to keratinized stratified squamous epithelium.

– The horny layer contains dead cells that are keratinized but retain nuclei.

– Function: Intermediate protection between keratinized epithelium and non-keratinized epithelium.

c. Stratified Squamous Non-Keratinized Epithelium:

– Found in the lining mucosa (soft palate, ventral surface of the tongue, floor of the mouth, labial mucosa, buccal mucosa, and palatine mucosa) and some areas on the dorsal surface of the tongue.

– Has 4 cell layers: basal layer, spinous layer, intermediate layer, and superficial layer.

– Function: Protection, lubrication, absorption.

2. Connective Tissue:

– Located beneath the epithelium, providing support and nutrition to the epithelium.

– Consists of two layers: lamina propria and submucosa.

a. Lamina Propria:

– Adjacent to the epithelium, containing blood vessels, nerves, lymphatics, and immune cells.

– Composed of two parts: papillary and reticular parts.

– The papillary part forms folds, increasing the surface area of contact with the epithelium.

– The reticular part forms a supporting network, helping to connect the epithelium to the submucosa.

b. Submucosa:

– Located beneath the lamina propria, containing glands, large blood vessels, nerves, and adipose tissue.

– Function: Nutrient supply, lubrication, and shaping the mucosa.

3. Functions of Lamina Propria:

– Strengthening the connection between the epithelium and connective tissue.

– Dispersing forces acting on the epithelial surface through connective tissue.

– Providing nutrients for the epithelium (epithelium is avascular).

4. Cell Types of Oral Mucosa Epithelium:

– Keratinocytes: the main epithelial cells, forming the horny layer.

– Nonkeratinocytes: supporting cells, including Langerhans cells, Granstein cells, Merkel cells, and melanocytes.

– Lymphocytes and Leukocytes: immune cells, protecting the mucosa from infection.

5. Classification of Oral Mucosa:

– Masticatory mucosa: mucosa that withstands chewing forces (hard palate, attached gingiva).

– Lining mucosa: mucosa that does not withstand chewing forces (soft palate, ventral surface of the tongue, floor of the mouth, labial mucosa, buccal mucosa, palatine mucosa).

– Specialized mucosa: mucosa with specialized functions (dorsal surface of the tongue and lateral sides of the tongue).

6. Lingual Papillae:

– Small folds on the surface of the tongue, containing taste buds.

– Filiform papillae are the only type that does not have taste buds.

Conclusion:

The oral mucosa is a complex structure, comprising numerous layers of cells and connective tissue, responsible for several essential functions for the body. Understanding the structure and function of the oral mucosa helps us take better care of our oral health.