Cavum Vergae

Cavum vergae is a normal anatomical variant in the human brain, which is seen in imaging as the posterior extension of the cave of septum pellucidum. It is sometimes described as the cavum septi pellucidi et vergae (or cavum septum pellucidum et vergae). It represents the persisntent embryonic fluid-filled space between the leaflets of the septum pellucidum.

Although the septal leaflets are ependyma-lined on their ventricular surfaces, the cavum itself is an extra-pial cavity that does not communicate with the ventricular system or the subarachnoid space.

Historically, cavum vergae has been referred to as the "sixth ventricle", but modern anatomical descriptions avoid ventricular numbering because it lacks key features of a true brain ventricle (for example, a continuous ependymal lining).