THE SUBARACHNOID ARTERIAL and venous circulations. according to Weed1, are actually invaginated within the cerebrospinal arachnoid circulation. The main and larger arteries of the brain and cord enter bilaterally and anteriorly and subsequently branch to enter the cortical subarachnoid around these organs. The lesser arteries send branches through arachnoid channels into the brain and cord proper.
This statement in no way abrogates the postulates of others in regard to the partial origin of spinal or cerebral fluid by osmosis, filtration, transudation or dialysis.