Abstract:

Objective　 To acquire partial anatomical parameters of posterior arch of atlas, and to provide a reference for design of screw-plate fixation system.　Methods　A total of 60 3D CT and 30 dry atlas specimens were used to measure anatomical data．The parameters included anterior-to-posterior thickness and superior-to-inferior height of the posterior ring of C1 at the midline as well as at 5mm, 10mm, 15mm lateral to the midline, angle of the posterior arch, the semi-distance of vertebral artery groove in inner surface and the semi-distance of vertebral artery groove in outer surface. The data gained from CTs and specimens was then compared.　Results　CTs measurement: The height of the center of posterior nodule was(9.48±0.95)mm, and the respective thickness was (7.80±1.60)mm. The angle of posterior arch was (130.70±12.31) °. The semi-distance of vertebral artery groove in inner surface and the semi-distance of vertebral artery groove in outer surface was (11.08±1.28) mm and (20.13±1.53) mm, respectively. Specimens measurement: The height and thickness of the midline was (9.97±2.18) mm and (7.44±1.32) mm, respectively. The angle of posterior arch was（135.07±9.59）°. The semi-distance of vertebral artery groove in inner and outer surface was（11.33±0.52）mm and（20.86±0.84） mm, respectively. The data of the semi-distance of vertebral artery groove gained from CTs was smaller than that measured from specimens with statistical difference.　Conclusion　Data measured from CT can present anatomical structure precisely and anatomical study is of referable significance in clinical practice.

Key words: Atlas, 　Measurement, 　Anatomy