Wormian bones

Wormian bones are a subset of the small intrasutural bones that lie between the cranial sutures formed by the bones of the skull vault. The title Wormian bones is reserved for abnormal intrasutural bones that are typically found around the lambdoid suture.

Some consider them abnormal only if greater than 10 in number.

Epidemiology

The reported incidence is variable, ranging from around 10% (in Caucasian skulls) and 40% (in Indian skulls) to 80% (in Chinese skulls). In general, males are more frequently affected than females.

Associations

Their associations are various, and inclusive of:

Wormian bones can also be idiopathic (anatomical variant). 

A useful mnemonic is PORKCHOPS.

Locations

History and etymology

Erroneously, these bones are named after the person who supposedly first described them:

  • Ole Worm (1624-1639), professor of Anatomy, Copenhagen, Denmark

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Article Information

rID: 5288
Section: Anatomy
Synonyms or Alternate Spellings:
  • Wormian bone

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Cases and Figures

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    Figure 1: photgraph
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    Case 1: Inca bone and sutural bones
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    Case 2
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    Case 3
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    Case 4: in osteogenesis imperfecta
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