Arachnoid villi function to do what?

Arachnoid villi function to do what?

• A. They drain CSF into the dural venous sinuses.
• B. They produce CSF.
• C. They regulate cerebral blood flow.
• D. They form the blood-brain barrier.

Answer: (A)

Arachnoid villi are responsible for absorbing cerebrospinal fluid (CSF) from the subarachnoid space into the dural venous sinuses. They act as one-way structures that allow CSF to drain down its pressure gradient into the venous system, helping to maintain normal CSF volume and intracranial pressure. This drainage pathway is why the correct choice is that they drain CSF into the dural venous sinuses. CSF is produced mainly by the choroid plexus, not by the arachnoid villi themselves. They do not regulate cerebral blood flow—that’s handled by mechanisms of cerebral autoregulation and vascular control. They also do not form the blood-brain barrier; that barrier is created by tight junctions of endothelial cells in brain capillaries, reinforced by astrocyte endfeet.

Arachnoid villi are responsible for absorbing cerebrospinal fluid (CSF) from the subarachnoid space into the dural venous sinuses. They act as one-way structures that allow CSF to drain down its pressure gradient into the venous system, helping to maintain normal CSF volume and intracranial pressure. This drainage pathway is why the correct choice is that they drain CSF into the dural venous sinuses.

CSF is produced mainly by the choroid plexus, not by the arachnoid villi themselves. They do not regulate cerebral blood flow—that’s handled by mechanisms of cerebral autoregulation and vascular control. They also do not form the blood-brain barrier; that barrier is created by tight junctions of endothelial cells in brain capillaries, reinforced by astrocyte endfeet.