Morphological and Morphometric Study of Atlas (C1) and Axis (C2) Vertebrae in Human Skeletons

Abstract

Background: The atlas (C1) and axis (C2) vertebrae are specialized cervical vertebrae that facilitate head movement and provide stability to the craniovertebral junction. Detailed morphometric knowledge of these vertebrae is essential for neurosurgical procedures, spinal fixation techniques, and forensic investigations.
Aim: To analyze the morphological variations and morphometric dimensions of atlas and axis vertebrae in human skeletal specimens and evaluate their clinical significance.
Methods: A retrospective osteological study was conducted in the Department of Anatomy, Government Medical College, Jammu, over 3 months. Thirty dry human vertebrae (15 atlas and 15 axis vertebrae) were examined. Various morphometric parameters including transverse diameter, anteroposterior diameter, vertebral canal dimensions, superior articular facet measurements, dens dimensions, and vertebral foramen dimensions were recorded using digital Vernier calipers. Morphological variations were documented. Statistical analysis was performed using SPSS version 26. Student’s t-test and Pearson correlation analysis were applied, with p<0.05 considered statistically significant.
Results: The mean transverse diameter of the atlas was 76.4 ± 4.8 mm, while the mean anteroposterior diameter measured 44.2 ± 3.5 mm. The average length of the dens in axis vertebrae was 15.8 ± 1.7 mm and the mean width was 9.1 ± 1.2 mm. Morphological variations were observed in 26.7% of specimens. Significant positive correlations were found between vertebral body dimensions and dens measurements (p<0.001).
Conclusion: Atlas and axis vertebrae exhibit significant morphometric variability. These findings provide valuable anatomical data for craniovertebral junction surgery, cervical instrumentation, and forensic anthropology.