The interventricular foramen (aka the foramen of Monro) joins the lateral ventricles of the brain with the anterior third ventricle. Cerebrospinal fluid then passes through the cerebral aqueduct (aka the aqueduct of Sylvius) into the fourth ventricle, and then through the median aperture (aka the foramen of Magendie) and the paired lateral apertures (aka the foramena of Lushka) into the thecal sac surrounding the spinal cord and the basilar cisterns of the skull. Cerebrospinal fluid (CSF) is a clear bodily fluid that occupies the subarachnoid space in the brain (the space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges). ...