The epithelium of the hard palate has a relatively thick keratinized layer indented by numerous, long papillae. The lamina propria is thicker in the anterior region of the hard palate, and closer to the bone than it is posteriorly. The submucosal layer contains dense connective tissues that firmly attach the soft tissues to the periosteum. The periosteum adheres more intimately to its overlying tissues than it does to the bone, making the palatal tissues collectively a mucoperiosteum. Because of the firm attachment, the mucoperiosteum can be peeled intact fairly easily from the bone.

The localized concentration of glands and specialized tissues in the submucosa makes it easy to distinguish four distinct zones in the hard palate.

The peripheral, or gingival, region is adjacent to the teeth or crest. The palatal gingiva (19) is similar to its labial counterpart (20), to which it is connected by interdental and retromolar papillae when teeth are present. The numerous, consistently dense collagenous connective fibers extending from the hard structures through the poorly differentiated overlying soft tissues to the surface layers make this region very firm, smooth, and resistant to mobility. The keratinized surface epithelium makes it appear pink.

The palatine raphe (21), a low ridge composed of tissues similar to those in the peripheral region, extends along the entire midline. The raphe is clearly differentiated, firm, and immovable. Its thickness is variable, being thinner over a high palatine torus.

Anteriorly, the ridge expands into a smooth pear- or oval-shaped prominence (22) that covers the incisive foramen. This prominence is the incisive, or palatine, papilla. Laterally extending various distances from the papilla and the raphe are irregular, sometimes branching ridges — the rugae, or transverse palatine folds (23). These hard ridges, which contain a core of dense connective tissue, are usually concentrated in the anterior portion of the palate, particularly around the incisive papilla. They are the vestigial remains of an auxiliary masticatory apparatus.

Fatty lobules (24) are packed anteriorly in the plains between the raphe, incisive papilla, and rugae, extending to the

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