The myelin sheath around axons in the CNS is formed by

Correct Answer: C

Rationale: Oligodendrocytes form myelin sheaths around CNS axons. Schwann cells myelinate PNS axons, neurons conduct, and 'none' is incorrect.

Correct Answer: C

Rationale: CSF fills the subarachnoid space between the arachnoid mater and pia mater, providing cushioning.

Correct Answer: B

Rationale: The longitudinal fissure is the deep groove separating the cerebral hemispheres. The corpus callosum connects them.

Correct Answer: B

Rationale: The primary visual area (V1) in the occipital lobe processes visual input from the eyes.

Correct Answer: C

Rationale: The hypothalamus is part of the diencephalon, below the thalamus, regulating autonomic and endocrine functions.