Question:medium
Which of the following is NOT TRUE about CSF?
Which of the following is NOT TRUE about CSF?
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Choroid plexus makes CSF; arachnoid villi only absorb it.
Updated On: Jun 24, 2026
- Removal of CSF during dural tap causes intense intracranial headache
- Normally contains no neutrophils
- Formed by arachnoid villi within the ventricles
- pH is less than that of plasma
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: We must find the statement that does not hold. Anchor on the difference between CSF production and CSF absorption. Production happens at the choroid plexus; absorption happens at the arachnoid villi.
Step 2: Option (c) claims arachnoid villi form CSF within the ventricles. That reverses the physiology, the villi drain CSF into the dural venous sinuses, they never secrete it, and they lie in the subarachnoid space, not the ventricles. This is the untrue statement and hence the answer.
Step 3: Verify the rest. A dural tap that drains fluid drops CSF pressure and provokes a positional low-pressure headache, so (a) holds. Healthy CSF has lymphocytes and monocytes but zero neutrophils, so (b) holds. CSF pH around 7.31 to 7.34 is just under plasma at 7.35 to 7.45, so (d) holds.
Step 4: Three statements are factually correct; only the arachnoid villi claim is wrong.
\[\boxed{\text{Formed by arachnoid villi within the ventricles}}\]
Step 2: Option (c) claims arachnoid villi form CSF within the ventricles. That reverses the physiology, the villi drain CSF into the dural venous sinuses, they never secrete it, and they lie in the subarachnoid space, not the ventricles. This is the untrue statement and hence the answer.
Step 3: Verify the rest. A dural tap that drains fluid drops CSF pressure and provokes a positional low-pressure headache, so (a) holds. Healthy CSF has lymphocytes and monocytes but zero neutrophils, so (b) holds. CSF pH around 7.31 to 7.34 is just under plasma at 7.35 to 7.45, so (d) holds.
Step 4: Three statements are factually correct; only the arachnoid villi claim is wrong.
\[\boxed{\text{Formed by arachnoid villi within the ventricles}}\]
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