The incisive foramen varies greatly in size and shape. The average foramen is about 3 x 3 mm, but a normal foramen may range up to 1 cm in diameter. It may be slit-like, oval, and heart-, pear- or diamond-shaped or any variation thereof, or highly irregular in outline. It may also be flat, its location marked only by four small perforations forming a diamond pattern. No matter which outline it assumes, the foramen is usually symmetrical and centered in the palate.

An incisive canal is always angled posteriorly. In the patient with anterior maxillary teeth, the foramen and canal (11) are well away from the apices of the teeth and the alveolar crest, even in a flat palate. However, when the ridge recedes after tooth loss, the foramen (12) may be immediately behind the residual crest. In such a situation, a conventional restoration seated on the vessels and nerves might be highly irritating. Although an implant-supported restoration would not impinge upon the vessels, great care must be taken in retracting a flap in the area and inserting implants.

In radiographs, the incisive foramen may produce a dark shadow varying in size, shape, and position. Its anatomical relationships are often distorted, particularly when anterior teeth are present. The foramen may be presumed healthy if the lamina dura around the apex of a normal tooth superimposed over the foramen is intact.

The posterior palatine foramen (13), also called the major palatine foramen, is usually not revealed in any type of radio-graphic projection. Any practitioner intending to incise or reflect tissues in the posterior regions of the maxillae must know where this foramen lies and the superficial pathways of its vessels. A mistake in or near the foramen is always serious. If the greater palatine artery is cut or torn here, it is almost impossible to stop the hemorrhage locally. The operator may have to expose and ligate the carotid artery to stem the bleeding — a drastic recourse.

The major palatine foramen marks the major opening into the oral cavity of the pterygopalatine canal, through which pass the palatine nerves and the descending palatine artery. One or two smaller brances of the canal generally open posterior to the major palatine foramen. These lesser foramina (14) supply the soft palate and tonsil.

The major palatine foramen lies lingual to the third molar (15), where the inner plate of the alveolar process meets the horizontal plate of the palatine bone. The emerging vessels may simply lie in a sharp angle (16) formed by the roof of the mouth and the

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