Variation of Wormian and Inca Bones in Adult Skulls

Abstract

Objective: Irregular and abnormal small additional bones called Wormian bones can be encountered between the skull bones. This study aimed to investigate the incidence, topographical distribution, morphology, and interrelationship of the Wormian and Inca bones in Central Anatolia Region dry adult skulls. Methods: In the study, 119 adult skulls were examined. The location and frequency of additional bones (Wormian) in the sutures in the cranium were determined. Skulls with Inca bones were identified. The Inca bones were typified in accordance with the literature and their dimensions in the transverse and sagittal axis were measured with a digital caliper. Results: Wormian bone was present in 33 of 119 adult skulls (27.7%). Of the 33 bones, 22 were detected in the male (66.66%) and 11 female (33.34%) skulls. The locations of the Wormian bones in the order of decreasing incidence were the lambdoid suture (16.0%, 19/119), pterion (16.0%, 19/119), lambda (7.6%, 9/119), asterion (2.5%, 3/119), and bregma (1.7%, 2/119). Nine Inca bones were found in the lambdoid region (27.3%, 9/33). Six of these bones (66.7%) were in the male skull. We found that two of these bones were incomplete lateral asymmetric, two were complete symmetric bipartite, two were incomplete asymmetric bipartite and three were incomplete median type. We found that 13 (10.9%) of the skulls in the study had metopic sutures and 0.8% had craniosynostosis. When the craniums with metopic suture were evaluated, it was found that 8 of them (61.5%) had additional bone. 50% of the Wormian bones were found in the lambdoid suture. Conclusion: It has been found that the incidence of Wormian bone increases with suture variations. It was determined that the frequency of Inca bone variation may vary depending on regional differences.