Intermediate Arachnoid Granulations Quiz

Q1. What are lateral lacunae in relation to arachnoid granulations?

• Subarachnoid cisterns around the brainstem
• Venous spaces adjacent to the superior sagittal sinus
• Arterial spaces within the falx
• Extensions of the lateral ventricles

Q2. Why does cerebrospinal fluid normally tend to move from arachnoid granulations into venous sinuses rather than in the reverse direction?

• Arachnoid granulations contain skeletal muscle valves
• Cerebrospinal fluid has a higher oxygen concentration
• Cerebrospinal fluid pressure normally exceeds venous pressure sufficiently to favor outward flow
• Venous sinuses actively pump cerebrospinal fluid

Q3. What relationship exists between arachnoid granulations and the inner table of the skull?

• They normally perforate the skull to reach the scalp
• They fuse with cranial sutures in infancy
• Large granulations may produce granular foveolae on the inner calvaria
• They form the diploic veins

Q4. How do arachnoid granulations typically change with age?

• They are largest only before birth
• They transform into choroid plexus
• They disappear completely after infancy
• They generally become more prominent with age

Q5. Which anatomical barrier must arachnoid projections traverse to reach the lumen of a dural venous sinus?

• Pia mater and cerebral cortex
• Pericranium and scalp
• Dura mater and the sinus wall interface
• Ependyma and choroid plexus

Q6. What type of flow is classically associated with arachnoid granulations?

• Active secretion of venous blood into the subarachnoid space
• Pressure-dependent bulk flow of cerebrospinal fluid
• Axonal transport of cerebrospinal fluid
• Diffusion of cerebrospinal fluid into neurons only

Q7. Why are arachnoid granulations often concentrated near the superior sagittal sinus?

• They provide a major venous interface for cerebrospinal fluid absorption
• The sinus contains the choroid plexus
• The superior sagittal sinus produces cerebrospinal fluid
• The sinus is continuous with the cerebral aqueduct

Q8. Which statement correctly distinguishes arachnoid granulations from subarachnoid trabeculae?

• Trabeculae produce cerebrospinal fluid while granulations anchor the brain to bone
• Both are identical structures with different names
• Granulations span from pia to cortex while trabeculae enter venous sinuses
• Granulations participate in absorption, while trabeculae span the subarachnoid space

Q9. What is the relationship of the pia mater to an arachnoid granulation?

• The pia becomes the venous endothelium
• The pia forms the dural sinus wall
• The pia does not form the granulation and remains applied to the brain
• The pia forms the outer capsule of every granulation

Q10. What may happen when a large arachnoid granulation protrudes prominently into a dural venous sinus on imaging?

• It always indicates a venous thrombus
• It proves obstruction of the cerebral aqueduct
• It represents an intracranial aneurysm
• It may appear as a benign filling defect