Determination of Sex using Foramen Magnum Measurements: A Cross-sectional Study from Karur, Tamil Nadu, India

Introduction: Sex determination is a fundamental goal in both forensic analysis and archaeological studies. The foramen magnum, the largest opening in the base of the skull, carries vital structures from the brain to the spinal cord. Because of its resistant nature, this portion of the skull is not only anatomically noteworthy but also useful for forensic investigations. Aim: To determine the sex of the individuals using measurements of the foramen magnum. Materials and Methods: A cross-sectional study was conducted in the Department of Forensic Medicine at Government Medical College and Hospital, Karur, Tamil Nadu, India, from September 2022 to February 2023. A total of 100 skulls were taken from individuals aged above 20 years. The transverse and Anteroposterior Diameters (APD) of the foramen magnum were measured using a digital vernier calliper. The area of foramen magnum was calculated using the Radinsky formula (R) and Teixeira formula (T). All variables were analysed using Levene’s test. The Binary Logistic Regression (BLR) model is run for all the foramen magnum variables. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 20.0 statistical software. Results: Males exhibited higher foramen magnum measurements than females, which were statistically significant (p<0.05). The mean APD for male skulls was found to be 38.10±2.90 mm, while that of the female skull was 36.08±3.46 mm. The mean Transverse Diameter (TD) for males was 29.89±3.17 mm, whereas for females it was 26.14±3.24 mm. The mean area (R) for male was 897.53±138.23 mm2 and for females it was 745.16±146.64 mm2 . The mean area (T) for males was 911.43±136.10 mm2 , while for females it was 769.45±141.67 mm2 . The analysis of APD indicated a p-value of 0.013; the Foramen Magnum Index (FMI) showed a p-value of 0.005 and other parameters, including TD and areas (R and T), demonstrated p-value <0.001. The overall sex determination rate was 73% when the BLR model was applied to all the parameters, with the highest accuracy at 78% for TD. Conclusion: Foramen magnum is regarded as an efficient tool for sex determination and it can be combined with other methods for higher accuracy.