Persistent ossiculum terminale

The ossiculum terminale appears as a secondary ossification centre of the dens between 3-6 years and normally fuses by 12 years. Failure of fusion results in a persistent ossiculum terminale (also called Bergmann's ossicle or ossiculum terminale of Bergmann) and is considered a normal anatomical variant of the axis.

It lies above the transverse alar ligament and is therefore considered to be stable and it very rarely causes symptoms.

Radiographic features

  • small, well-corticated ossicle at the tip of the dens
  • dens is typically normal in height 4

Differential diagnosis


Spinal anatomy
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Article Information

rID: 1864
Section: Anatomy
Synonyms or Alternate Spellings:
  • Bergman's ossicle
  • Ossiculum terminale of Bergmann
  • os terminale

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