Switching bone

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Worm bones (in yellow) belong to the switching bones

Shifter bones , also known as spandrels , arise from the appearance of unusual bone sutures that do not exist in the normal skull or from the fact that bone sutures are retained in adults that are otherwise only present in the fetus or in the first years of life. Switching bones are counted among the accessory bones .

Switch bones are clinically insignificant. They are neither a handicap nor a malformation , but an anatomical variation.

Examples

An example of a switching bone is the Inca leg ( Os incae ). The anterior fontanel bone ( Os bregmaticum ) is the switching bone that takes the place of the large fontanel and is square, trapezoidal, round, oval, P-like or biscuit-shaped.

Worm's bones ( Ossa wormiana ) are smaller switching bones that slide between two skull bones without significantly affecting the course of the skull sutures and the overall shape of the skull.

The zygomatic arch ( arcus zygomaticus ), which is split into two parts by a special bone suture, is called Os japonicum (Japanese leg) because this formation is more common in Japanese . About 2.2% of the female and 1.7% of the male population of Anatolia have an os japonicum . These values ​​roughly correspond to the values ​​of the population on the main Japanese island and other East Asian countries.

Individual evidence

  1. ↑ E. Bücheler and M. Thelen: Introduction to Radiology: Diagnostics and Interventions. Georg Thieme Verlag, 2006, ISBN 3-133-16011-7 , pp. 52-53. limited preview in Google Book search
  2. ↑ P. Jeanty et al: Prenatal diagnosis of wormian bones. In: Journal of Ultrasound in Medicine 19, 2000, pp. 863-869. PMID 11127012
  3. ↑ A. Anil et al .: Incidence of os japonicum in Anatolian dry skulls and plain cranium radiographs of modern Anatolian population. In: Journal of Cranio-Maxillo-Facial Surgery 28, 2000, pp. 217-223. doi : 10.1054 / jcms.2000.0142

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