Fig. 3

Schematic of the model domains. a A representation of the cerebrospinal fluid compartments. The x and arrow parallel to the spinal cord indicate the anatomic correspondence and orientation of the one-dimensional model. This orientation was chosen to match the direction in which CSF samples are accessed during sequential sampling of CSF through lumbar puncture [31]. b Protein efflux locations in the spine. Blood-derived proteins pass from blood by diffusion into the CSF space and exit it along nerve roots. c A representation of the three-dimensional model domain as an annular channel. The boundary conditions for this model are shown on the domain surfaces