Cavum septum pellucidum
The septum pellucidum consists of thin translucent plate of two laminae which are frequently fused and lie between the anterior part of the body, the genu and the rostrum of the corpus callosum and the superior surface of the fornix. If these laminae are not fused then a fluid-filled space or 'cavum' is present, hence the term cavum septi pellucidi. The cavum septum pellucidum is present at birth but in more than 80% of individuals it is obliterated by the age of 3 to 6 months. It is up to 1cm in width and the walls are parallel. It is an enclosed space and is not part of the ventricular system or connected with the subarachnoid space in man. A cyst
of the cavum septum pellucidum may occur which is distinguished by the lateral bowing of the walls of the septum pellucidum which are more than 1 cm apart. These may be symptomatic. The significance of a persistent cavum septi pellucidi in the adult population is uncertain but may be associated with abnormalities of the limbic system.