MORPHOMETRIC EVALUATION OF FORAMEN MAGNUM IN DRY HUMAN SKULLS

The foramen magnum is an important landmark in the posterior part of the cranial base, which is largely formed by the occipital bone. The dimensions of the foramen magnum are clinically important because of the vital structures passing through it. We studied thirty six dry human skulls of known sex and measured antero-posterior and transverse diameters with the help of Vernier caliper. Additionally surface area and Index of foramen magnum were also calculated. Oval shape is the main type of morphological variant found in this study. The transverse diameter of the foramen magnum was in a range of 25.75-34.25mm in males, whereas it was between 26-31.75mm in females. The anteroposterior diameter was in a range of 35 to 39.75mm in males while it was 29.5 to 34.75mm in females. The mean area of foramen magnum in males was 876.88±88.83mm whereas it was 776.87±68.51mm in females. In contrast to the area, the mean foramen magnum index was higher in females (89.01±6.84mm) compared to males (81.75±5.99mm) and this difference was also statistically significant (p<0.01). The prospective study will help surgeon for reference value for determining feasibility of transcondylar surgical approach, which are being done in an increasing trend in recent times for brain stem lesion.