The structure that forms the lateral wall of the third ventricle and is part of the diencephalon is the?

The structure that forms the lateral wall of the third ventricle and is part of the diencephalon is the?

• A. Thalamus
• B. Hypothalamus
• C. Pineal gland
• D. Epithalamus

Answer: (A)

The lateral wall of the third ventricle is formed mainly by the thalamus, a large paired structure in the diencephalon. The third ventricle runs along the midline between the two thalami, so its sides are bounded by the thalamic bodies. The hypothalamus sits inferior to the thalamus and forms the floor of the third ventricle rather than its lateral wall. The pineal gland, part of the epithalamus, lies posterior to the third ventricle and does not constitute the lateral wall. So the thalamus is the correct structure.

The lateral wall of the third ventricle is formed mainly by the thalamus, a large paired structure in the diencephalon. The third ventricle runs along the midline between the two thalami, so its sides are bounded by the thalamic bodies. The hypothalamus sits inferior to the thalamus and forms the floor of the third ventricle rather than its lateral wall. The pineal gland, part of the epithalamus, lies posterior to the third ventricle and does not constitute the lateral wall. So the thalamus is the correct structure.