Medial sigmoid depression: a panoramic pseudoforamen in the upper ramus.

A radiolucency resembling a foramen was observed on a number of panoramic radiographs in the upper ramus just below and slightly anterior to the sigmoid notch. The radiolucency may be unilateral or bilateral and does not correspond to the location of any known major foramina in this region. Eighty-eight skulls with mandibles were examined, and representative samples were photographed and radiographed in order to replicate this foramen-like radiolucency. The radiolucency corresponded to an osseous depression observable in some specimens in the medial portion of the ramus just below the sigmoid notch area. The incidence of this phenomenon in a study of 1,986 panoramic radiographs was also determined.