Selasa, 31 Januari 2012

The Anatomy of Mouth (Oral Cavity)

MOUTH (ORAL CAVITY)


The mouth, also referred to as the oral or buccal cavity, is formed by the cheeks, hard and soft palates, and tongue. Forming the lateral walls of the oral cavity are the cheeks – muscular structures covered on the outside by skin and lined by nonkeratinized stratified squamos  epithelium. The anterior portions of the cheeks terminate in the superior and inferior lips.
The lips (labia) are fleshy folds surrounding the orifice of the mouth. They are covered on the outside by skin and on the inside by a mucous membrane. The transition zone where the two kinds of covering tissue meet is called the vermilion. This portion of the lips is nonkeratinized, and the color of the blood in the underlying blood vessels is visible through the transparent surface layer of the vermilion. The inner surface of each lip is attached to its corresponding gum by a midline fold of mucous membrane called the labial frenulum.
The orbicularis oris muscle and connective tissue lie between the external integumentary covering and the internal mucosal lining. During chewing, the cheeks and lips help keep food between the upper and lower teeth. They also assist in speech.
The vestibule of the oral cavity is bounded externally by the cheeks and lips and internally by the gums and teeth. The oral cavity proper extends from the vestibule to the fauces, the opening between the oral cavity and the pharynx or throat.
The hard palate, the anterior portion of the roof of the mouth, is formed by the maxillae and palatine bones, is covered by mucous membrane, and forms a bony partition between the oral and nasal cavities. The soft palate forms the posterior portion of the roof of the mouth. It is an arch-shaped muscular partition between the oropharynx and nasopharynx and is lined by mucous membrane.
Hanging from the free border of the soft palate is a conical muscular process called the uvula. On either side of the base of the uvula are two muscular folds that run down the lateral side of the soft palate. Anteriorly, the palatoglossal arch (anterior pillar) extends inferiorly, laterally, and anteriorly to the side of the base of the tongue. Posteriorly, the palatopharyngeal arch (posterior pillar) projects inferiorly,nlaterally, and posteriorly to the side of pharynx. The palatine tonsils are situated between the arches, and the lingual tonsil are situated between the arches, and the lingual tonsil is situated at the base of the tongue. At the posterior boder of the soft palate, the mouth opens into the oropharynx through the fauces.

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