Background The axis has superior and inferior articular facets that facilitate cervical mobility. The superior facets articulate with the inferior facets of the atlas for head rotation, whereas the inferior facets connect with the superior facets of C3 for neck movement. Trauma or degeneration can cause atlantoaxial instability. The articular facet of the odontoid process forms the median atlantoaxial joint with the anterior arch of C1, enabling head rotation. Dens fractures represent 50-60% of axis fractures, with type II being the most common. Treatment includes anterior screw fixation or posterior stabilization, which requires careful consideration because of the proximity of the vertebral artery. Methods A cross-sectional study was conducted using 52 dry adult human axis vertebrae with unspecified age and sex. This study aimed to investigate the shape and morphological differences between the superior and inferior articular facets and the atlanto-odontoid facet. All facets were measured using a digital vernier caliper. Data were statistically analyzed using IBM SPSS Version 21. Results The length and width of the superior articular facet were 16.67±1.26 mm and 15.14±1.42 mm on the right side, and 16.76±1.71 mm and 15.23±1.51 mm on the left side. The length and width of the inferior articular facet were 11.46±1.45 mm and 9.74±1.28 mm on the right side, and 11.51±1.40 mm and 9.50±1.15 mm on the left side, respectively. The height and width of the articular facets of the dens were 9.67±1.43 mm and 7.86±0.90 mm, respectively. conclusion These measurements help surgeons navigate the axis vertebra and minimize vertebral artery damage, given the relationship between the superior articular facet and vertebral artery. Understanding the articular facet dimensions is essential for safe screw placement. This study will help surgeons perform surgical procedures on the axis and safely apply new orthopedic techniques.

Atlanto-Odontoid Facet, Axis Vertebra, Inferior Articular Facet, Morphometry, Odontoid Process, Superior Articular Facet.