The white matter of the CNS is always:

Correct Answer: C

Rationale: White matter in the CNS consists of myelinated axons organized into tracts that carry signals between regions. It is not always deep to gray matter (e.g., cerebral cortex has superficial gray matter), it is myelinated (not unmyelinated), and it includes both sensory and motor fibers, not just sensory.

Correct Answer: A

Rationale: The hypothalamus regulates body temperature, thirst (via osmoreceptors), and sleep-wake cycles. The pons and medulla handle respiration, the pituitary gland releases hormones, and the cerebrum manages higher functions.

Correct Answer: D

Rationale: All statements are correct: the medulla has decussating fibers (e.g., pyramids), is part of the reticular formation, contains cranial nerve nuclei (e.g., IX, X), and regulates heart rate, blood pressure, and breathing.

Correct Answer: B

Rationale: The blood-brain barrier (BBB), formed by tight junctions in capillaries, restricts ions like Na⁺ to protect the brain. Lipid-soluble compounds and water pass more easily, while lipids are not specifically restricted.

Correct Answer: A

Rationale: The basal ganglia include the caudate nucleus and lentiform nucleus (putamen + globus pallidus). The infundibulum is hypothalamic, red nucleus is midbrain, and insula is cortical.