Correlation Between Endocranial Capacity and Size of Foramen Magnum with Special Reference to Sex.

ABSTRACT

Background: Endocranial capacity is an important parameter in the study of human evolution, race and sex determination of skull. Diameters of foramen magnum are important because vital structures passing through it may endues compression and for sex determination of skulls. Correlation between endocranial capacity and area of foramen magnum was reported in mammals. This relation in human can be used to determine sex of damaged skulls. Methods: 150 dry skulls and 30 CT scan images of living subjects were studied. Endocranial capacity of skulls was measured by modified Breitinger’s method. Diameters of foramen magnum were measured by vernier calipers and its area was calculated by formula endocranial capacity of CT scan images measured by planimetry. Diameters and area of foramen were measured automatically. Results: The Mean endocranial capacity of male and female skulls were 1367.3ml and 1255.2ml respectively by modified Breitinger’smethod and by CT scan image planimetry method were 1347.1ml and 1130ml. The mean longitudinal diameter of foramen magnum in male was 33.4mm and female was 33.1mm and by CT Imaging method in male was 38.5mm and female was 35.2mm. The mean transverse diameter of foramen magnum in male was 28.5mm and female was 27.3mm and by CT Imaging method in male was 29.1mm and female was 27.6mm. Conclusion: Endocranial capacity, transverse diameter and area of foramen magnum of male skulls were greater than females. A significant positive correlation was observed between endocranial capacity and area of foramen magnum in male and female skulls, but highly significant positive correlation was observed when both sexes were considered together. Living subjects showed a significant positive correlation between endocranial capacity and area of foramen magnum when both sexes were considered together.