
A canal between two of the cavities (called the third and fourth ventricles) in the brain through which cerebrospinal fluid passes. ... (12 Dec 1998) ...
Found on
http://www.encyclo.co.uk/local/20973

Aqueduct of Sylvius: A canal that communicates between the third and fourth ventricles in a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord. The four ventricles consist of the two lateral ventricles, the third ventricle and the fourth ventricle: Lateral ventricles: The lateral ven...
Found on
http://www.medterms.com/script/main/art.asp?articlekey=9175

a canal in the midbrain, connecting the third and fourth ventricles of the brain.
Found on
https://www.infoplease.com/dictionary/aqueduct-of-sylvius
No exact match found.