The walls of the interventricular foramina also contain choroid plexus, a specialized CSF-producing structure, that is continuous with that of the lateral and third ventricles above and below it.

[1] The walls of the interventricular foramina contain choroid plexus, a specialized structure that produces cerebrospinal fluid.

[3] Narrowing of the foramen is more common in children[6] and linked to: inflammation and scarring from congenital infections, particularly TORCH infections; developmental abnormalities, including of the basilar artery and choroid plexus; and abnormal surrounding tissue growths, such as colloid cysts, subependymal giant-cell tumours, nodules and harmatomas.

[3] If an obstructing mass is too large or too difficult to remove endoscopically, an open operation or the insertion of an artificial path between the ventricles and peritoneum may be required.

[3][6] Because of the intimate nature of pathways within the brain, such operations may result in damage to nearby structures, with complications including anterograde amnesia, inability to move half the body, akinetic mutism and disconnection syndromes.