1. CSF is present within the CNS as well as around it.
2. This fluid communicates with each other on the roof of medulla oblongata through 3 apertures, viz. Foramina of Luschka and foramen of Magendie.
3. This communication ensures constant pressure of CSF within as well as outside the CNS.
4. In the absence of this communication, there would be a pressure difference within as well as outside the CNS which will result in disturbances in the activities of CNS. Moreover, intercranial pressure would rise.
