MORPHOMETRIC EVALUATION OF THE FORAMEN MAGNUM AND VARIATION IN ITS SHAPE AND SIZE: A STUDY ON HUMAN DRIED SKULL

The foramen magnum is an important landmark located in the posterior part of the cranial base formed by the occipital bone. The purpose of this study was to evaluate the measurements of the foramen magnum in human dried skull and to note the variations in the shape and size of the foramen magnum. Additionally area and index of the foramen magnum were also calculated. Fifty human dried skulls of unknown age and sex were obtained from the department of CMCH Bhopal and FHMC Tundla. Foramen magnum were examined macroscopically for their different shapes. Anteroposterior and transverse diameters, foramen magnum area & foramen magnum index were measured. The foramen magnum shapes were determined as round shaped in 22%, oval shaped in 16%,egg shaped in16%, and irregular in18%,tetragonal in 12% penta and hexagonal 8% each. The mean A-P and transverse diameters of the foramen magnum was determined 38.75mm and 33.44mm respectively. In 4%of skull, the occipital condyle was observed to protrude in to the foramen magnum. The mean foramen index and foramen magnum area were 87.68 & 970.57mm². The data obtained may be useful to the neurosurgeon in analysing the morphological anatomy of craniovertebral junction in trans condylar approach for brain stem lesion.