Which structure is primarily responsible for the reabsorption of cerebrospinal fluid into the venous circulation?

• A Arachnoid granulations projecting into the superior sagittal sinus ✓
• B Choroid plexus of the fourth ventricle
• C Ependymal cells lining the cerebral aqueduct
• D Perivascular spaces surrounding perforating arteries

Explanation

CSF passes from the subarachnoid space into the dural venous sinuses chiefly through arachnoid granulations (pacchionian bodies) along the superior sagittal sinus, driven by the pressure gradient between CSF and venous blood. The choroid plexus produces CSF rather than absorbing it. B smaller amount drains along perineural sheaths of cranial and spinal nerves and through nasal lymphatics, but this is a minor route.

Reference: Snell's Clinical Neuroanatomy, 8th ed.

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