ABSTRACT
Variations in the morphometry of the vertebral artery groove which presents on the superior surface of surgery. This necessitates preoperative information about the vertebral artery groove. The present study aimed at assessment of the quantitative and qualitative anatomy of the vertebral artery groove of the atlas on 76 dry specimens with comprehensive analysis. This included the study of different linear parameters of the vertebral artery groove such as the distance from the midline, the thickness, the depth of the lateral and medial entrances, the depth of the transverse foramen and the width of the transverse foramen. In addition, the different forms of posterior and lateral bridging over the groove and their percentages were assessed. It was found that the minimum distance from the midline to the medial most edge of the vertebral artery groove in the inner and outer cortex of the posterior arch were 5 and 15 mm respectively. These data suggested that dissection of the posterior aspect of the posterior arch should remain 5 and 15 mm on the inner and outer cortex from the midline. It was also found that 44 [57.96%] of the examined specimens presented with a bridge formation which projects over the vertebral artery groove. From these 44 atlas presented with a bridge formation, 42 [55.26%] presented with partial bridges and 2 [2.63%] presented with complete posterior bridges. These bridges may interfere with the normal function of vertebral artery. It was concluded that before any craniovertebral intervention is performed, collection of the morphometric data of the vertebral artery groove must be carried out