The Morphometric Analysis of Inferior Clivus and Foramen Magnum and its Importance in Surgical Approaches.

Purpose: The purpose of this study was to evaluate the posterior and posterolateral approaches based on quantitative analysis of the foramen magnum and inferior clivus. Methods: The bony structures, distances and angles related to the foramen magnum area were measured in 25 cadaveric skulls. These measurements included the relationship of the foramen magnum to the occipital codyle, the hypoghossal canal, the jugular process of the occipital bone, the mastoid process and the sigmoid sinus. Results: The condylar length, width and thickness on the right side were 23.58±1.49 mm and 7.77±1.41 mm respectively. The lateral width of foramen magnum was 29.98±3.01 mm and anteroposterior width was 35.71±2.64 mm. The distance between the lateral edge of foramen magnum and the lateral edge of sigmoid sinus was found greater than the distance between the lateral edge of foramen magnum and the mastoid process. Conclusions: The findings showed that the anatomy of foramen magnum and its related structures is important for surgical approaches. These findings also demonstrate that the anatomical obstructions could be drilled to gain wide access to this region. [ABSTRACT FROM AUTHOR]