Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Anatomy

Background : Variations of the vertebral artery are important for diagnostic and interventional angiographic procedures as well as for the neurosurgeons and orthopaedic surgeons.Aim of the work: To describe the anatomical variations of the vertebral artery and to provide a quantitative and qualitative anatomy of the vertebral artery groove of the atlas vertebra using MDCTA in Egyptian population and dry atlas vertebrae. Material and Methods: The present study consisted of 100 MDCTA images obtained from Radiology department, faculty of medicine, Cairo University and Nile Scan Imaging Center. Each radiological image was evaluated for the vertebral artery origin, level of entrance into foramen transversarium, calibre, distance from the midline and the presence of ponticulus posticus. 50 atlas vertebrae were obtained from the Anatomy department, faculty of medicine, Cairo University. Each vertebral artery groove was evaluated for the presence of ponticulus posticus, inner and outer distances from the midline, width and thickness. Results: Most of arteries arose from the subclavian artery (91% on the left and 99% on the right). The left vertebral artery arose directly from the aortic arch in 7% of cases and was absent in 2% of cases. In the majority of cases, the arteries entered the foramen transvesarium at C6 (91% on the left and 93% on the right). The mean diameter of the artery was greater on the left (3.67 ± 1.07 mm) as compared to the right side (3.36 ± 0.93 mm). Ponticulus posticus was detected in 47% of cases in radiological images and 96% of dry bones.Conclusion: Variations of the vertebral artery and vertebral artery groove are common in the Egyptian population. The most important variations are the aortic origin of the vertebral artery and presence of ponticulus posticus

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