The differential diagnosis of isolated ossicles in the region of the dens axis.

: 2 osteological specimens of the atlanto-occipital region with accessory ossicles sitting on the dens axis are described. Considering the anatomical and radiological literature, the differential diagnosis of isolated accessory ossicles in the region of the dens axis is discussed (e.g. os odontoideum, ossiculum terminale BERGMANN persistens, ossifications of the ligamentous apparatus).