Morphometric Analysis of Atlas and Its Clinical Significance: An Anatomical Study of Indian Human Atlas Vertebrae

The morphometry of atlas is very important for surgeries in the occipitocervical region. There are studies explicitly differing in the results concerning some key anatomic measurements, mandating an additional evaluation of anatomic landmarks of atlas. Therefore, this study was aimed to evaluate the various dimensions of the atlas quantitatively relevant for various surgeries. A total of 30 adult atlas vertebrae of Indian origin were studied. The distances were measured by digital vernier calliper. The transverse diameter and maximum anteroposterior dimension of vertebral canal of atlas had a mean of 27.31 ± 2.74 and 29.44 ± 2.54 mm, respectively. The vertebral artery groove thickness on atlas is 3.79 ± 1.08 mm on right and 4.05 ± 00.86 mm on left, respectively. The mean distance from sagittal midline to the innermost edge of the vertebral artery groove is 10.73 ± 2.92 mm on right side and 09.72 ± 2.56 mm on left side. Overall, 74% of superior articular facets were found to be oval in shape and 26% in kidney shape. On the basis of these findings, we concluded that the thickness of the vertebral artery groove is satisfactory for surgical fixation techniques and the dissection on the posterior arch of atlas can be extended to 12 mm from the midline through the posterior approach.