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Aim: The classic variants in superior articular facets of atlas such as, variability in shape, presence of notch, constrictions, partial or complete separation of facets, and presence of pressure facets, have been reported to a limited extent in relation to ergonomics of cranio-vertebral joint. Objective: The objectives of the present study were to report the analyzed morphological features and metrical values of superior articular facets of the atlas. The morphological features which were included in this study were variability in shapes, constrictions and partial or complete separation of facets. The metrical measure included the surface area measurement of the facets. Material and Methods: This study was carried out on 50 (100 sides) dry atlas vertebrae from the Department of Anatomy, St John's Medical College, Bangalore, India. The superior articular facets were studied for the shape and symmetry, constrictions and partial or complete separation of facets. The surface area of the facets were measured by using Image J (Image processing and analysis in JAVA) tool, that was primarily designed to measure and analyze different metrics. Results: The mean surface area on the right side was 157.3 ± 29.02, and on the left side, it was 158.5 ± 24.85. Oval, irregular, kidney and figure of eight shapes were observed either on both sides or on one side. Bilateral constrictions of facets were seen in 58 % of vertebrae. Bilateral, complete separations of facets were seen in 30% of vertebrae Conclusion: The observations of the present study are important to understand the ergonomics of the cranio-vertebral joint and they are helpful for academicians, neuro-surgeons, clinicians and radiologists in day to day clinical practice. [ABSTRACT FROM AUTHOR]