The ventricular system consists of lateral, third and fourth
ventricles and the cerebral aqueduct.
The lateral ventricle is located within the cerebral hemisphere
and is approximately C-shaped. It communicates, via the interventircular
foramen (foramen of Monro) with the third ventricle
The third ventricle is a midline, slit-like cavity. Its lateral
wall consist of the thalamus and hypothalamus. Caudally, the third ventricle
becomes continuous with the cerebral aqueduct (aqueduct of Sylvius).
The aqueduct of Sylvius extends throughout the midbrain,
linking the third and fourth and ventricles.
The fourth ventricle is located between the brain stem (pons
and medulla) and the cerebellum. A median aperture (foramen of Magendie)
and two lateral apertures (foramina of Luschka) communicate with the subarachnoid
space surrounding the brain.
Each ventricle contains choroid plexus, which secretes CSF.
CSF flows in the direction: lateral ventricle ->third ventricle -> cerebral
aqueduct-> fourth ventricle-> subarachnoid space
The combined ventricular system and subarachnoid space contains
about 150 ml of CSF, this volume being produced several times each day.
CSF is reabsorbed into the venous system through arachnoid
villim which project into the superior sagittal dural sinus.