Anatomical and clinical correlates of the precondylar tubercle

The possible presence of the precondylar tubercle should be considered in order to avoid misinterpretation in radiographic images or confusion during surgical intervention. This study examines dry skulls in order to describe and report the frequency of the precondylar tubercle and similar variations at the anterior margin of foramen magnum. Axial CT was used to demonstrate the appearance of bilaterally prominent precondylar tubercles in one skull. Precondylar tubercles were observed in 10% of the skulls. Other simulating observations included the presence of a midline spur, bilateral depression anteromedial to the occipital condyles, third occipital condyle, and a partly divided occipital condyle. Most of these variations were associated with septation of the hypoglossal canal. The presence of a mere precondylar tubercle is not expected to produce neurological manifestations, but its possible association with other variations should be considered.