====== Inner membrane ======
There is no clear plane between the [[dura]] and [[arachnoid]] in situ. Instead of the virtual [[subdural space]], there is a dura-arachnoid interface layer, which is structurally the weakest throughout the meninges. Extravasation of blood within the dural border layer splits it, leaving a few tiers of dural border cells over the arachnoid. These cells cover the internal surface of the hematoma, proliferate, and later on, form the inner membrane. The [[outer membrane]] is related to hematoma enlargement because of the repetitive hemorrhages whereas the inner membrane is related to liquefaction of the subdural hematoma. As the inner membrane plays a pivotal role in the pathophysiogenesis and determination of the location of [[chronic subdural hematoma]], histologic, ultrastructural, and clinical analyses were performed with correlations to the dura-arachnoid interface and the so-called "[[subdural space]]"
((Yamashima T. The inner membrane of chronic subdural hematomas: pathology and pathophysiology. Neurosurg Clin N Am. 2000 Jul;11(3):413-24. PMID: 10918010.))