Boundary condition (BC) template set for a supine patient with neutral head orientation in the OR. Displacement BCs: Surface 1: Stress-free, i.e., free to deform, Surface 2 and 5: slide along the cranial wall but are not permitted to move along the normal direction, Surfaces 3,4: Fixed, i.e., cannot move. Pressure BCs: Surfaces 1, 2 and 3 reside at atmospheric pressure, Surfaces 4 and 5 are still submerged in CSF and therefore do not allow fluid drainage.