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Home , Submucosa

Subject: Oral Biology Chapter: Oral Topic: Definition, Classification and Functions of Oral Mucous Membrane Teacher: Dr. Munawar Aziz Khattak LECTURE I

2 Learning Objective

• At the end of this lecture, the students will be able to know about the;  Oral Mucous Membrane  Classification  Functions  General Structure

3 Oral Mucous Membrane Cont’d… Oral Mucous Membrane Cont’d… Oral Mucous Membrane Cont’d…

• The moist lining of the , nasal passages and other body cavities that communicate with the exterior • In the oral cavity this lining is called the oral mucous membrane or • Anteriorly;  continuous with the skin of the lip through the vermilion border • Posteriorly;  continuous with the mucosa of the CLASSIFICATION OF ORAL MUCOSA

BASED ON FUNCTION 1. Masticatory mucosa 2. Lining or reflecting mucosa 3. Specialized mucosa BASED ON TYPE OF EPITHELIUM 1. Keratinized 2. Nonkeratinized BASED ON FUNCTION

1. Masticatory Mucosa (Gingiva and Hard Palate) 2. Lining or Reflecting Mucosa (Lip, Cheek, Vestibular Fornix, Alveolar Mucosa, Floor of the Mouth and Soft Palate) Oral Mucous Membrane Cont’d… 3. Specialized mucosa (dorsum of the tongue and taste buds) Oral Mucous Membrane Cont’d…

• The masticatory mucosa is bound to and does not stretch  It bears forces generated when food is chewed • The lining mucosa is not equally exposed to masticatory forces.  It covers the musculature and is distensible  It makes up all the surfaces of the mouth except for the dorsum of the tongue and the masticatory mucosa • The specialized (sensory) mucosa is so called because it bears the taste buds, which have a sensory function BASED ON TYPE OF EPITHELIUM

1. Keratinized Mucosa (Masticatory Mucosa, Specialized Mucosa, Vermilion Zone) 2. Nonkeratinized Mucosa (Lining Mucosa) FUNCTIONS OF ORAL MUCOSA

1. Defense 2. Lubrication 3. Sensory 4. Protection 1. Defense Oral Mucous Membrane Cont’d… Oral Mucous Membrane Cont’d… Oral Mucous Membrane Cont’d…

• The integrity of the oral epithelium is an effective barrier for the entry of the microorganisms • Infection occurs if the epithelial integrity is broken down resulting in bacterial invasion • It also secretes antibodies and has an efficient humoral and cell mediated immunity 2. Lubrication Oral Mucous Membrane Cont’d…

• The secretion of salivary glands keeps the oral cavity moist • A moist oral cavity helps in speech, mastication, swallowing and in the perception of taste 3. Sensory Oral Mucous Membrane Cont’d…

• The oral mucosa is sensitive to touch, pressure, pain and temperature • These sensations are better appreciated in the anterior part of the mouth • The sensation of taste is felt only in the anterior 2/3rd of the dorsum of the tongue • Swallowing, gagging, retching and salivating reflexes are initiated by receptors in the oral mucosa  Touch sensations in the soft palate results in gag reflex 4. Protection

• The oral mucosa protects the deeper tissues from mechanical forces DEFINITIONS AND GENERAL CONSIDERATIONS Oral Mucous Membrane Cont’d…

• The oral mucosa consists of epithelium and connective termed • The oral mucosa is attached by a loose termed submucosa to the underlying structure which may be bone or muscle • The oral mucosal epithelium is of stratified squamous type Comparison of Oral Mucosa with Intestinal Mucosa Oral Mucous Membrane Cont’d…

• Oral mucosa is composed of two layers, epithelium and connective tissue (lamina propria) • Intestinal mucosa has an epithelium, lamina propria, and is attached by the submucosa to the underlying muscles  is present between lamina propria and submucosa in the intestinal mucosa BUT not in oral mucosa Comparison of Oral Mucosa with Skin Oral Mucous Membrane Cont’d…

• Skin is composed of two layers, epidermis and • Oral mucosa is composed of two layers, epithelium and connective tissue (lamina propria) Epidermis (epithelium) of Skin • Always orthokeratinized • Has stratum lucidum Epithelium of Oral Mucosa • May be nonkeratinized or keratinized  If keratinized, the keratinization may be ortho or parakeratinized • Lacks a layer, termed stratum lucidum Oral Mucous Membrane Cont’d…

Dermis (connective tissue) of Skin • Has skin appendages; namely the hair follicles, sebaceous glands and sweat glands • Lacks salivary glands Lamina Propria of Oral Mucosa • Lacks appendages • Has salivary glands GENERAL STRUCTURE Oral Mucous Membrane Cont’d…

• The two layers, epithelium and connective tissue form an interface that is folded into corrugations • Papillae of connective tissue protrude toward the epithelium carrying blood vessels and • Some of the nerves actually pass into the epithelium • The epithelium does not contain blood vessels • The epithelium, in turn, is formed into ridges that protrude toward the lamina propria • These ridges interdigitate with the papillae and are called epithelial ridges Oral Mucous Membrane Cont’d… Oral Mucous Membrane Cont’d…

• The two tissues (epithelium and connective tissue) are intimately connected • At their junction there are two different structures with very similar names;  The basal lamina and the basement membrane • The basal lamina is evident at the electron microscopic level and is epithelial in origin • The basement membrane is evident at the light microscopic level For Questions & Queries: [email protected]

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