1. Pineal tumors also can cause compression of the cerebral aqueduct, resulting in a noncommunicating hydrocephalus.

2. The cerebral aqueduct (Aqueductus mesencephali, mesencephalic duct, sylvian aqueduct or aqueduct of Sylvius) is a conduit for cerebrospinal fluid (CSF) that connects the third ventricle to the fourth ventricle of the ventricular system of the brain

3. Aqueductus cerebri: 1 n a canal connecting the third and fourth ventricles Synonyms: Sylvian aqueduct , cerebral aqueduct Type of: canal , channel , duct , epithelial duct a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance