[The canalis basilaris medianus on the x-ray and computed tomogram (author's transl)].

The canalis basilaris medianus is a persistent venous canal in the Clivus, which was first described by Gruber. Depending on the type of the canal, course and projection the canal is mostly recognized on the x-ray as a longitudinal or diagonal translucent band, seldom as a round translucence; on the computed tomogram depending on the directional course in the layer as a round translucence of a longitudinal translucent band. It was detectable in 4,3% (14/332) of the examined x-rays (occipitomental projection, skull base) and in 6/154 (3,8%) of the computed tomograms of the skull base. By measuring computer-tomographically the increase of the CT-absorption values in the canal lumen after injection of a contrast medium, it was confirmed that there is a vessel in the canal. The differential diagnosis to canalis cranio-pharyngeus, foveola pharyngea and fracture is discussed.