*The cerebral (mesencephalic) aqueduct is a ventricular tube running through the midbrain which connects the third and fourth ventricles. It contains [[Cerebral Spinal Fluid - Anatomy & Physiology|cerebral spinal fluid]] which offer it immunological protection. | *The cerebral (mesencephalic) aqueduct is a ventricular tube running through the midbrain which connects the third and fourth ventricles. It contains [[Cerebral Spinal Fluid - Anatomy & Physiology|cerebral spinal fluid]] which offer it immunological protection. |