Wormian bones compared to a normal skull
Skull of a 21-year-old man with Wormian bones
|Anatomical terms of bone|
Wormian bones, also known as intra sutural bones, are extra bone pieces that can occur within a suture (joint) in the cranium. These are irregular isolated bones that can appear in addition to the usual centres 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 once found in the skull of a hydrocephalic adult.
Wormian bones may also be seen in:
- Osteogenesis imperfecta
- "Kinky-hair" Menke's syndrome
- Cleidocranial dysostosis
- Hypothyroidism and hypophosphatasia
- Otopalatodigital syndrome
- Primary acro-osteolysis
- Down's syndrome
These causes can be remembered by the mnemonic "PORKCHOPS".
Derivation of the name
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.
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- 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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