Which statement best summarizes three important functions of cerebrospinal fluid?

• A. Mechanical shock absorber, buoyancy, and an exchange of materials between blood vessels and brain tissue
• B. Mechanical shock absorber
• C. Buoyancy
• D. Exchange of materials between blood vessels and brain tissue

Answer: (A)

Cerebrospinal fluid serves three important roles: it cushions the brain to absorb mechanical shocks, provides buoyancy so the brain floats within the skull and reduces its effective weight, and enables exchange of materials between brain tissue and the blood—delivering nutrients and removing waste via circulation in the ventricles and subarachnoid space. The statement that includes all three functions is the best because it accurately encompasses the full set of CSF roles. Options listing only one function each miss the other two essential aspects.