Cerebrospinal fluid is formed by arachnoid villi of choroid plexus. About 75 percent of Cerebrospinal Fluid is formed in lateral ventricle. From lateral ventricle it goes to 3rd ventricle via foramen of monro also known as interventricular foramen.

From there, CSF from 3rd ventricle goes to 4th ventricle via aqueduct of sylvius. CSF from 4th venticle goes to venous sinuses via foramen of luschka and magendie.