Morphological characteristics of the first part of the vertebral artery.

Because of their anatomical localization, vertebral arteries were neglected in research for a long period of time. Vertebral arteries are responsible for about 30% of the brain blood supply. The aim of this study was to examine the vertebral artery's course in the first segment, and to define the anatomic variations and percentage of their appearance in the adult population using CT angiography. The data derived from this study may find useful application in a wide range of medical fields, such as anatomy, radiology and surgery. For that purpose during a 6-month period we examined 30 patients with CT angiography. The origin of the vertebral artery in all 30 patients was from the subclavian artery. The diameter of the left vertebral artery was from 1.6-5.20 mm., average 3.35 mm. The diameter of the right vertebral artery was from 1.64-5.40 mm., average 3.19 mm. Hypoplasia of the vessel was found in four patients. We found no aplasia of the vessel in this series. A contorted course was found in 12 (40%) patients. In all 30 (100%) patients the vertebral artery entered the foramen transversum at the level of the sixth cervical vertebra. Although the incidence of anatomical variations is rare, their presence is significant in the diagnostic and surgical procedures in the head and neck region. Insufficient knowledge can lead to serious iatrogenic injures.