A Morphologic and Morphometric Study of the Vermian Fossa and Internal Occipital Crest in Adult Indian Human Skulls

Abstract

Introduction: The inner surface of the squamous part of occipital bone shows a prominent internal occipital crest that descends and bifurcates close to foramen magnum to enclose a small depression called vermian fossa. It has been reported that the internal occipital crest and vermian fossa affect the dural venous sinuses close to it and influence the cerebrospinal fluid flow. Few studies have reported morphology the morphology and morphometric features of vermian fossa. There is a paucity of literature regarding the morphology and morphometry of the internal occipital crest. Hence, the present study evaluated the morphological and morphometric details of the vermian fossa and internal occipital crest. Objectives: To provide morphologic & morphometric data of the vermian fossa and internal occipital crest in the Indian population. Materials and Methods: This was a cross-sectional study, with a sample size of 64, carried out for a period of three months in the Department of Anatomy. The fossa's morphometric dimensions and the vermian fossa's different shapes observed were documented. The internal occipital crest was observed for shape & length. All data was tabulated, analyzed, and summarized using mean and standard deviation. Results: The vermian fossa was present in 56(82.35%) bones. The type 1 variety was observed in 48(70.6%), type 2 variety in 1 (1.1%) bone and type 3 - atypical variety in 10.3%. The mean length and width of the vermian fossa was 8.9 ±4.41 mm and 8.02±3.50 mm, respectively. The internal occipital crest was sharp in 37(54.4%) bones, rounded in 24(35.3%) bones and wide in 6(8.8%) bones and ill-defined in one bone. The mean length of the internal occipital crest from the internal occipital protuberance to the posterior margin of the foramen magnum was 4.16±0.56 cm. Conclusion: An accurate knowledge of morphology and morphometry of vermian fossa and internal occipital crest and their variations is of significance in diagnostic and therapeutic performance of clinicians and radiologists. Variations in normal anatomical features need to be explored. Hence, this is of importance to anatomists and morphologists. KEY WORDS: occipital crest, vermian fossa, morphology, morphometry, cerebellum.