What is the normal circulating CSF volume in adults?

What is the normal circulating CSF volume in adults?

• A. 50 mL
• B. 100 mL
• C. 150 mL
• D. 200 mL

Answer: (C)

In adults, the cerebrospinal fluid (CSF) reservoir sits around 150 mL. CSF is produced continuously and circulates through the ventricles and subarachnoid space, being turned over several times a day, but the total volume maintained in the system at any one time is about 125–150 mL. This balance keeps the brain buoyant and maintains the chemical environment needed for neurons. The other options (much smaller or larger volumes) don’t match the typical CSF volume stored in the adult system, so roughly 150 mL is the standard circulating amount.

In adults, the cerebrospinal fluid (CSF) reservoir sits around 150 mL. CSF is produced continuously and circulates through the ventricles and subarachnoid space, being turned over several times a day, but the total volume maintained in the system at any one time is about 125–150 mL. This balance keeps the brain buoyant and maintains the chemical environment needed for neurons. The other options (much smaller or larger volumes) don’t match the typical CSF volume stored in the adult system, so roughly 150 mL is the standard circulating amount.