Morphometric study of the posterior arch of atlas vertebra in the Serbian population

Abstract

Introduction. Groove for the vertebral artery and the suboccipital nerve, is located on the superior surface of the posterior arch of the first cervical vertebra (the atlas). Presence of bony variations may transform the groove into incomplete/complete canal, causing compression of its structures and consequently symptoms of vertebro-basilar insufficiency. The aim of the present study was to determine the incidence and extent of morphological variations of the posterior arch of the atlas vertebra. Material and Methods. The investigation was conducted on 41 atlas vertebrae, part of the Osteological Collection of the Department of Anatomy of the Faculty of Medicine in Novi Sad and the Faculty of Medicine in Nis. According to the shape of the posterior arch, the atlas vertebrae were classified into three classes. The measurements of maximum width and height diameters of the incomplete/complete canal for the vertebral artery were performed. All the measurements were done using open source software for image analysis, Image J. Results. The results of the study showed that in our sample of atlases the most common class was class I (78.05%), and class III the least frequent (7.32%). There was no statistically significant difference in the observed measurements of the atlas anatomical variations between the right and left side. Conclusion. Morphometric analysis of the superior surface of the posterior arch of the atlas vertebra has shown the existence of variations and their importance has been discussed.