A case of "accessory falx cerebri".

We report on a 12-year-old boy who underwent a right frontotemporoparietal craniotomy for complete extirpation of three cavernous hemangiomas of the temporal lobe. On this occasion, an accessory dural septum was observed that spanned, in the direction of the corona, the temporo-occipital base upward to the lower parietal area. It produced a deep notch in the cortex, was supplied by a small leptomeningeal artery, and probably contained small venous sinus. Embryological considerations and clinical relevance are discussed.