Wormian bones, also known as intra sutural bones are extra bone pieces that occur within a suture in the cranium. These are irregular isolated bones which 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 may also be seen in:
- Osteogenesis imperfecta
- "Kinky-hair" Menke's syndrome
- Cleidocranial dysostosis
- Hypoparathyroidism and hypophosphatasia
- Otopalatodigital syndrome
- Primary acro-osteolysis
- Down's syndrome
The causes can be remembered by the mnemonic "PORKCHOPS".
Derivation of the name 
Wormian bones are named for Ole Worm, Professor of Anatomy at Copenhagen, 1558–1654. He taught Latin, Greek, physics and medicine. His description of the extra-sutural bones contributed to the science of embryology.
Additional image 
See also 
- <radiopaedia.org/articles/wormian-bones>Saladin, Kenneth (August 2006). Anatomy & Physiology: The Unity of Form & Function (4th ed.). McGraw-Hill. ISBN 0-07-331608-3.
- Gray, Henry; Warren Harmon Lewis (1918). Anatomy of the Human Body. Lea & Febiger.
- Parente, K; Mercado-Deane, MG; Brummund, T (2001). "Radiological Case of the Month". Archives of pediatrics & adolescent medicine 155 (6): 731–2. doi:10.1001/archpedi.155.6.731. PMID 11386967. Retrieved 2008-11-02.
- Dr. Akram Abood Jaffar. "Sutural bones". Archived from the original on 2009-10-25.
- Glorieux FH, Osteogenesis Imperfecta, Best Practice & Research Clinical Rheumatology. 22:1, pp. 85-100. 2008
- Wormian Bones: Differential Diagnosis #6, The Radiology Blog, Published April 27, 2012
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