cerebral aqueduct
The cerebral aqueduct is the part of the ventricular system that carries cerebrospinal fluid from the third ventricle to the fourth ventricle. So, this must be the part of the ventricular system that was blocked. The central canal is the space where CSF flows through the spinal cord. It is continuous with the 4th ventricle. The foramina of Luschka (lateral aperatures) and foramen of Magendie (median aperature) are small foramina in the 4th ventricle that allow the CSF to leave the ventricular system and enter the subarachnoid space. The interventricular foramina are passages from the lateral ventricles that allow the CSF to enter the 3rd ventricle.