Ligamentous structures in foramen magnum: sectional anatomy, CT and MRI

Abstract

Objective To study the thin sectional anatomy and CT and MR imaging of ligamentous structures of foramen magnum (FM).Methods Six formalin fixed (10%) specimens including head and neck were selected, and each specimen was imaged with CT and MR. Three specimens were sectioned with frozen section technique, the others were sectioned with plastination. Ligamentous structures of FM on continuous thin sections were observed and compared with the images of CT and MRI.Results Continuous sections of 3.0 mm slice thickness for the axial, coronal, and sagittal planes of FM sectioned with frozen section technique were obtained.Continuous thin sections of 1mm slice thickness for the axial, coronal, and sagittal planes of FM sectioned with plastination were obtained. The resulting sections demonstrated excellent distinction of ligamentous structures of FM (including ligamentum alare, ligamentum transversum, membrana tectoria, anterior obturator membrane of atlas, posterior obturator membrane of atlas, and anterior atlanto-axial ligament). A good overall correlation between sections and images of CT and MR was found.Conclusions In combination with CT and MRI, continuous thin sections of FM offers a better understanding of ligamentous structures of FM.