Fig 4.

Examples of CSF velocity simulations for maximal systolic flow for a single axial section in an idealized model of the SAS with different cord shapes or sizes. The asymmetric CSF flow pattern from Fig 3 is assumed for this simulation. The upper image shows velocities for a SAS containing a cord assumed to have a cylindric shape. The next image shows systolic flow when the cord is modeled with an elliptic rather than a circular cross-section. The boundary conditions are otherwise the same as those for the upper image. Note that changing the shape of the spinal cord changes the flow pattern during systole. The bottom image illustrates velocities in a model with a larger cylindric spinal cord and a smaller SAS. Note the marked increase in velocities due to a smaller SAS.