Wormian bones

Wormian bones (Sutural bones)
Wormian bones compared to a normal skull
Skull of a 21-year-old man with Wormian bones
Details
Identifiers
Latin	Ossa suturale
TA	A02.1.00.043
FMA	59327
Anatomical terms of bone []

Wormian bones, also known as intra sutural bones, are extra bone pieces that occur within a suture (joint) in the cranium. These are irregular isolated bones that appear in addition to the usual centers of ossification of the cranium and, although unusual, are not rare. They occur most frequently in the course of the lambdoid suture, which is more tortuous than other sutures. They are also occasionally seen within the sagittal and coronal sutures. A large wormian bone at lambda is often called an Inca bone (Os Incae), due to the relatively high frequency of occurrence in Peruvian mummies. Another specific wormian bone, the pterion ossicle, sometimes exists between the sphenoidal angle of the parietal bone and the great wing of the sphenoid bone. They tend to vary in size and can be found on either side of the skull. Usually, not more than several are found in a single individual, but more than one hundred have been found in the skull of a hydrocephalic adult.

Wormian bones are a marker for some diseases and important in the primary diagnosis of brittle bone disease: osteogenesis imperfecta.

Wormian bones may also be seen in:

The causes can be remembered by the mnemonic "PORKCHOPS".

Wormian bones are named for Ole Worm, professor of anatomy at Copenhagen, 1588–1654. He taught Latin, Greek, physics and medicine. His description of the extra-sutural bones contributed to the science of embryology.