In this coronal section of a normal childs head (from the front) the dura and arachnoid membranes surrounding the brain lie closely against each other. The potential space in between them is called the subdural space.
The space below the arachnoid membrane is called the sub arachnoid space and is filled with cerebrospinal fluid. This fluid acts as a shock absorber and helps to cushion the brain from injury.
In the center of the brain are the ventricles. These are a network of cavities which contain cerebrospinal fluid. Within the ventricular system is the choroid plexus which produces cerebrospinal fluid.