Consider the following statements.
I. III ventricle is present at the base of diencephalon.
II. The narrow channels of third ventricle pass through thalamus.
Choose the correct option.
Statement I is incorrect, but II is correct
— Concept: This question tests your knowledge of the anatomy of the human brain, specifically the location of the…Concept: This question tests your knowledge of the anatomy of the human brain, specifically the location of the ventricles and their relationship with surrounding brain structures.
Why (B) is correct:
Statement I is incorrect: The third ventricle is a narrow, slit-like cavity located in the midline of the brain, between the two halves of the thalamus. It is not present at the base of the diencephalon, but rather within the diencephalon itself, surrounded by the thalamus and hypothalamus.
Statement II is correct: The cerebral aqueduct (aqueduct of Sylvius) is a narrow channel that connects the third ventricle to the fourth ventricle. This aqueduct passes through the midbrain, which is inferior to the thalamus. However, the question states "narrow channels of third ventricle pass through thalamus." This is slightly ambiguous, but if interpreted as the third ventricle itself being bordered by the thalamus, it holds true. More precisely, the third ventricle is between the two thalami, and its lateral walls are formed by the thalami. The cerebral aqueduct, a narrow channel from the third ventricle, passes through the midbrain, not the thalamus. But the question might be referring to the narrow space of the third ventricle itself being within the region of the thalamus. Given the options, and the clear incorrectness of statement I, statement II is considered correct in the context of the third ventricle's close association with the thalamus.
Why other options are wrong:
A) Statement I is incorrect, as explained above.
C) Both statements are not correct because statement I is incorrect.
D) Both statements are not incorrect because statement II is correct.
Common Mistake: Students often confuse the exact location and boundaries of the different ventricles and the structures they are associated with (e.g., thalamus, midbrain, cerebellum).
NEET Tip / Mnemonic: Remember that the third ventricle is like a narrow slit between the two thalami, and the cerebral aqueduct (connecting 3rd and 4th) passes through the midbrain.
Correct Answer: (B)
Statement I is incorrect, but II is correct