Abstract

Background: Morphometric analysis of the foramen magnum of dry human skulls in Gujarat region was carried out to demonstrate the anatomical variations in morphology. The measurements of the foramen magnum are clinically important because vital structures passing through it. There are certain diseases associated with compression of structure present in foramen magnum like arnold chiari malformation (tonsillar herniation), achondroplasia, stenosis of foramen magnum, meningioma and atlanto-occipital fusion. Objectives: The aim of this study was to measure anteroposterior & transverse diameter of foramen magnum, surface area and index of foramen magnum and to observe its various shapes. Materials and methods: 326 dry skulls of adult human being were studied. Antero-posterior and Transverse Diameter were measured by using a digital vernier caliper. The surface area and foramen magnum index were calculated. The cranial base was visually assessed for the shape of foramen magnum. Results: The mean antero-posterior and transverse diameter of the foramen magnum were 34.18 ± 2.74 mm and 28.49 ± 2.13 mm respectively. The mean surface area and the foramen magnum index were 766.86 ± 104.76 mm2 and 83.60 ± 6.21 mm respectively. The percentages of different shapes of foramen magnum were: Oval (42.33%), Round (32.82%), Tetragonal (8.59%), Hexagonal (7.67%), Pentagonal (4.60%), and irregular (3.99%). Conclusion: The knowledge of various dimensions & shape of the foramen magnum help to determine some malformations like arnold chiari syndrome in which the transverse diameter is increased. The antero-posterior diameter of foramen magnum was more than the transverse diameter and most common shape of foramen magnum was found to be Oval.

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