Some controversy, albeit of academic interest only, exists as to the exact location of a subdural haematoma. Classical teaching is that it is located in the potential space between the arachnoid layer and inner layer of the dura; however, no such space really exists. Rather the arachnoid-dura junction is composed of "avascular tissue with flake-like [...] cells stacked in several layers with narrow intercellular clefts" 10 . Bleeding occurs within this multicellular layer, with these cells located on both sides of the haematoma 9-10 . This possibly accounts for why some acute haematomas appear to have multiple compartments, usually ascribed to intermittent bleeding ref required .