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ORAL AND NASAL CAVITIES Diane Bick Ph.D. Reading : Gartner and Hiatt Chapter 13 and beginning of Chapter 12; Klein and McKenzie, pp234, 325, 335 Learning Objectives: 1. Know the components of the oral and nasal cavities and describe the epithelia lining each. 2 . Describe and differentiate the different papillae on the human tongue. 3. Recognize the distinctive musculature of the tongue. 4. Know the different cell types within a taste bud and their different roles in the taste sensation. 5. Understand the structure, function and development of the different histological components of the tooth. 6. Describe the histological composition of the olfactory epithelium and describe the roles of the different cell types. Key Words: Papillae, taste bud, olfactory epithelium, respiratory epithelium, dentine, enamel, cementum. ORAL CAVITY. Responsible for the ingestion and preliminary processing of food. Formed by the lips, cheek, hard and soft palate and the floor of the mouth. The walls of this cavity are lined with a stratified squamous epithelium. 1. LIPS External aspect: thin skin with keratin, hairs, sebaceous glands and eccrine sweat ducts. Transitions to the moist, inner surface at the transitional or vermilion zone. Transitional zone has no sweat ducts or hair follicles and is the site of the transition from a keratinized epithelium to a non-keratinized stratified squamous epithelium. Underlying rich capillary network and the presence of kerato-hyaline, which makes the epithelium more transparent, causes the deep red colour. The submucosa of the lips contains numerous small mucus and seromucus glands. The central core of the lips is composed of striated muscle embedded in elastic fibro-connective tissue. 2. TONGUE A freely moving structure attached to the floor of the pharynx. A mass of striated muscle covered by a mucous membrane. The muscle fibers of the tongue cross one another in three planes and four layers ; they are grouped together in bundles separated by connective tissue, serous, mucous and seromucus glands. The ventral surface of the tongue is covered by a thin, non-keratinizing stratified squamous epithelium continuous with that of the floor of the mouth. The dorsal surface however is subject to more stress and is covered by a thick keratinizing stratified squamous epithelium. Dorsal Tongue Divided into the anterior two-thirds and the posterior third, these two regions arise from different embryonic origins. They meet at a V-shaped boundary.
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The posterior portion contains low dome-shaped elevations of lymphoid tissue, the lingual tonsils. The overlying stratified squamous, non-keratinizing epithelium extends down into the lymphoid tissue as deep pits or crypts. Mucus glands secrete into these crypts and keep them free of debris. The surface epithelium of the anterior zone of the dorsal surface of the tongue is raised in a series
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This note was uploaded on 12/25/2010 for the course NEUROBIOLO MSI taught by Professor Rogerj.bick during the Spring '10 term at University of Texas Health Science Center at San Antonio.

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