Chapter 9. ORAL MUCOSA

The oral cavity consists of two parts: anterior - vestibule (fig. 9.1, 9.2), and posterior - oral cavity proper, including the tongue, teeth, their supporting tissues (alveolar bone, periodontal ligaments), salivary glands and tonsils. The vestibule is the space between lips, cheeks and teeth. The oral cavity proper is bounded by teeth and alveolar processes of upper and lower jaws, hard and soft palate, and the floor of the mouth.

Fig. 9.1. Vestibule, frenulum of lower lip

Fig. 9.2. Vestibule, frenulum of upper lip

STRUCTURE OF MUCOSA IN DIFFERENT PARTS OF THE MOUTH

Lips. Red border of the lips is a transition zone (wet-dry line) (fig. 9.3) between the skin and oral mucosa. The red border is covered by stratified squa-mous epithelium. Frenulums are located on the midline of the vestibule of upper and lower lips.

Fig. 9.3. Lower lip: red border, transition zone (wet-dry line), mucosa

Fig. 9.4. Cheek and Stenton?s duct

Fig. 9.5. Gingiva: interdental gingival papilla, marginal gum, alveolar gum

Fig. 9.6. Front part of hard palate with incisive papilla

Cheeks. Because of the thick submucosal layer, mucosa of the cheeks is mobile. In the submucosa of the cheek small vessels and yellowish glands of Fordyce are located. At the level of the second upper molar Stenton parotid duct opens.

Gums. Gingiva consists of three areas: marginal gingiva, alveolar gingiva, gingival papillae. Gingiva has no submucosal layer, so the mucosa is intimately connected with the periosteum of the alveolar bone. The epithelium of marginal gum is keratinized.

Hard palate. The mucosa of the hard palate in the region of palatal suture and close to the alveolar bone has no submucosa. Near the central incisors there is incisive papilla.