crest, or they may lie in an undercut (17) in the ridge or in a groove (18) in the hard palate. No matter where it lies, the canal's emergence is marked by the foramen's sharp posterior wall and lower, smooth anterior lip. The sharper, higher wall can be located by palpation in most mouths.

Although most of the soft tissues in the hard palate are dense, compact, and firmly bound to one another, it is worth noting that the palatine blood vessels and nerves are encased in loose connective tissues. These tissues form a continuous sheath around the vessels and nerves, separating one from the other and from the surrounding tissues. There is a fairly generous amount of loose connective tissue accompanying the vessels and nerves as they pass through the pterygopalatine canal and emerge from the major palatine foramen. The sulcus in which the vessels lie between the alveolar crest and the hard palate is occupied by a wedge-shaped cushion of connective tissue. The amount of loose connective tissue diminishes proportionately as the vessels narrow as they proceed anteriorly and branch.

Because of the looseness of the connective tissue sleeve around the arteries, veins, and nerves, these can be relatively easily separated from the underlying tissues, including the periosteum. This permits a certain amount of flexibility in reflecting a flap, as the vessels can slip within their sleeve without straining or tearing. Most implant procedures require including the vessels and nerves intact within the flap. By remaining intact, blood loss is minimized, and the flap heals more quickly and with fewer problems.

As with most other important oral landmarks, resorption of the alveolar crest will bring the major palatine foramina and its emerging vessels closer to the operative field. Again, because of the severe consequences of a surgical slip in this area during even a supposedly minor surgical procedure, the operator must proceed with extreme caution.

It is not necessary to expose these vessels, and the operator should not attempt to do so. If he has any doubt at all about the location of the foramina or the course of its emerging vessels, he should avoid the procedure.

Visually, the hard palate easily can be distinguished from the soft palate by the different character of their soft tissues. The soft palate's tissues are reddish with a yellowish tint, thin almost to the point of translucency, loosely textured, and movable. Those of the hard palate are pink like the gingiva, thick, uniform in character, and immovable.

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