Wormian bones

A.Prof Frank Gaillard et al.

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.


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.


Their associations are various, and inclusive of:

Wormian bones can also be idiopathic (anatomical variant). 

A useful mnemonic is PORKCHOPS.


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
Share article

Article information

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

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Figure 1: photgraph
    Drag here to reorder.
  • Drag
    Case 1: Inca bone and sutural bones
    Drag here to reorder.
  • Drag
    Case 2
    Drag here to reorder.
  • Drag
    Case 3
    Drag here to reorder.
  • Drag
    Case 4: in osteogenesis imperfecta
    Drag here to reorder.
  • Updating… Please wait.

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.