Question

Which structure forms the roof of the third ventricle?

• A. Corpus callosum
• B. Fornix
• C. Tela choroidea
• D. Septum pellucidum

Hint:

The fornix = major output tract of the hippocampus, also forms the roof of the third ventricle.

Answer 1

The Correct Option is B

The third ventricle is a narrow cavity located within the brain, part of the ventricular system which contains cerebrospinal fluid. The roof of the third ventricle is primarily formed by the structure known as the fornix. The fornix is a C-shaped bundle of nerve fibers in the brain and is a major output tract of the hippocampus. The fornix arches over the thalamus and forms the superior boundary of the third ventricle. It is critical in the limbic system, contributing to functions such as memory formation.
Therefore, the correct answer is the fornix, which forms the roof of the third ventricle.
Other structures:

• The corpus callosum is a large bundle of neural fibers connecting the two cerebral hemispheres, located above the fornix.
• The tela choroidea refers to a layer involved in the secretion of cerebrospinal fluid and not in forming the roof.
• The septum pellucidum is a thin membrane located between the lateral ventricles and is not associated with the roof of the third ventricle.