How are the third and fourth ventricles linked?

The third and fourth ventricles are linked by the cerebral aqueduct, also known as the aqueduct of Sylvius. The cerebral aqueduct is a narrow channel that connects the third ventricle, located in the centre of the brain, to the fourth ventricle, which is located at the back of the brain. The cerebral aqueduct allows cerebrospinal fluid, which bathes the brain and spinal cord, to flow from the third ventricle to the fourth ventricle.