The arachnoid granulations (Pacchionian granulations) project into which dural sinus and function in CSF absorption?

• A Straight sinus
• B Cavernous sinus
• C Superior sagittal sinus ✓
• D Sigmoid sinus

Explanation

Arachnoid granulations (villi) are finger-like projections of the arachnoid mater that herniate through the dura into the superior sagittal sinus and its lateral lacunae, forming one-way valves for bulk CSF absorption into the venous blood when CSF pressure exceeds venous pressure. Calcified arachnoid granulations are seen on CT as small pits in the inner table lateral to the superior sagittal sinus. Blockage or obliteration of these granulations (e.g., after subarachnoid haemorrhage or meningitis) causes communicating hydrocephalus. The straight sinus drains the deep cerebral veins and great cerebral vein (of Galen); the cavernous sinus receives the ophthalmic veins.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.