Which ventricle is located in the narrow channel between the cerebral hemispheres and communicates with the lateral ventricles through the foramen of Monro?

• A. Third ventricle
• B. Fourth ventricle
• C. Lateral ventricle
• D. Cerebral aqueduct

Answer: (A)

The third ventricle is a narrow, midline cavity located between the paired thalami in the diencephalon, right in the space between the cerebral hemispheres. It receives CSF from the two lateral ventricles through the foramina of Monro and then channels it onward to the fourth ventricle via the cerebral aqueduct. That placement and connections fit the description precisely.

The fourth ventricle sits behind the pons and medulla, between the brainstem and cerebellum, and connects to the third ventricle via the cerebral aqueduct. The lateral ventricles are the large, C-shaped spaces within each cerebral hemisphere and connect to the third ventricle through the foramina of Monro but are not themselves the narrow channel between the hemispheres. The cerebral aqueduct is the narrow passage linking the third and fourth ventricles, not the space between the hemispheres.