What causes CSF to flow? Since matter at rest tends to stay at rest until acted upon, there must be some mechanism in the brain causing cerebrospinal fluid to move from the choroid plexus to other areas of the central nervous system.  Is there some kind of hydraulic pump that causes it to flow from one area to the next?

Also, the ventricular system seems to be more of a continuous cavity, rather than a unidirectional closed circuit. How does the fluid make it's way into the far corners of the lateral ventricles, and other nooks and crannies of the ventricular system without the risk of fluid in some areas staying stagnant?
The following is taken from the bio answer https://biology.stackexchange.com/questions/94/how-does-cerebrospinal-fluid-circulate-in-the-central-nervous-system


  Venous system has generally low pressure, thus sucking the CSF up to drainage points. Speaking about drainage we also should consider the fact that the venous system has a pressure lower than the atmospheric pressure and much lower than pressure in any middle-sized arterial vessels. This is reached by having elastic walls and by transmitting the negative pressure from the mediastinum during the inhale, when the diaphragm and the thorax expand. This negative pressure propagates mostly to the connected vessels, including sinus system. Due to the elastic wall other parts of venous system can accommodate this negative pressure constrict their lumen, but not the sinus system which has a hard external framework formed by dura mater and bones. That is here we can measure the lowest pressure and this is the pressure that sucks CSF in into the venous system



click here for bonus .gif of this process happening in an MRI