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Persistent ossiculum terminale

The ossiculum terminale appears as a secondary ossification center 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 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
  • usually in the midline
  • dens is typically normal in height 4

Differential diagnosis

Anatomy: Spine
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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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Cases and figures

  • Figure 1: diagram
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  • Case 1
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  • Case 2
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