What does it mean cavum vellum interpositum?

The cavum vellum interpositum is a space located in the brain, specifically between the two layers of the tela choroidea, which is part of the lateral ventricles. It contains cerebrospinal fluid (CSF) and is situated above the corpus callosum and below the fornix. This anatomical feature is significant for understanding brain structure and function, particularly regarding the circulation of CSF. Its presence can also be relevant in certain neurological conditions and imaging studies.