subdural space subdural space the subdural space (or subdural cavity) is a potential space that can be opened by the separation of the arachnoid mater from the dura mater as the result of trauma, pathologic process, or the absence of cerebrospinal fluid as seen in a cadaver. in the cadaver, due to the absence of cerebrospinal fluid in the subarachnoid space, the arachnoid mater falls away from the dura mater. it may also be the site of trauma, such as a subdural hematoma, causing abnormal separation of dura and arachnoid mater. hence, the subdural space is referred to as "potential" or "artificial" space. subdural spacediagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. ("subdural cavity" visible at left.)diagrammatic transverse section of the medulla spinalis and its membranes. (subdural cavity is colored green, labeled at bottom and top right.)detailsidentifierslatinspatium subdurale, cavum subduralemeshd013355ta98a14.1.01.109ta25380fma83803anatomical terminology