The dynamic interaction between the intracranial compartments. At the start of systole, an arterial volume suddenly flows into the cranium. This causes an immediate increase in the intracranial pressure (ICP). According to the Monro-Kellie doctrine, this increase in ICP is countered by a succession of flush flows through the venous and CSF compartments. The temporal coordination of these flush flows is now well documented and is organized according to the venous and CSF viscosities and flow resistances and brain compliance. The arterial peak flow (1) is first transmitted to the cervical CSF flow (2), the venous blood flow (3) and, lastly, the ventricular CSF flow (4).