AbstractIntroductionThe motion of the brain relative to the skull is influenced by the architecture of the subarachnoid space (SAS), and in particular, by the arachnoid trabeculae. In previous studies of these structures, specific shapes were identified. However, the work presented here shows much finer detail of the SAS geometries using SEM and TEM.Materials and methodsThese images were acquired by maintaining the SAS structure of a rat using glutaraldehyde formaldehyde to strengthen the tissues via crosslinking with the biological proteins.ResultsThe results showed the detailed shape of five dominant arachnoid trabeculae structures: single strands, branched strands, tree like shapes, sheets, and trabecular networks. Each of these architectures would provide a different response when exposed to a tensile load and would provide different levels of resistance to the flow of the cerebrospinal fluid (CSF) within the SAS.ConclusionThis very detailed level of geometric information will therefore allow more accurate finite element models of the SAS to be developed.