ORIGINAL ARTICLE ON THE MORPHOLOGICAL STUDY OF FORAMEN MAGNUM

Abstract

Introduction: Centrally in the deepest part of posterior cranial fossa is the largest foramen, Foramen magnum surrounded by basilar part of occipital bone on either side. Because of relation between the FM and the vital structures passing through it, study on its morphometric features is of great signicance. Aim and objectives: The objectives were to study the various morphological features of the foramen magnum in dry skulls using an analogue Vernier calliper. Materials and methods: 50 dry skulls (8 base skulls, 42 full skulls) of human cadaver of unknown age and sex were obtained to study the morphometric features like shapes, anteroposterior and transverse diameters and FM index in the department of Anatomy, Kanyakumari Government medical college, Asaripallam. Results: The classication of determined shapes were round in 29.7%, hexagonal in 18.2%, egg shaped in 16.9%, oval in 12.7%, tetragonal in 11.4%, pentagonal in 3.7% and irregular in 7.4%. In 12% of the skulls the occipital condyles were found to protrude into the foramen. The mean value of anteroposterior and transverse diameter was found to be 35 ±1.2mm, and 28 ± 1.4 mm respectively and average foramen magnum index was 1.25 ± 0.8. Conclusion: Foramen magnum dimensions are used for sex determination. The structural integrity of foramen magnum is usually preserved in re accidents and explosions due to its resistant nature and secluded anatomical position. The data obtained from protrusion of occipital condyles would help in neurosurgical approach of foramen magnum meningiomas.