Collection of blood that forms between the inner surface of the skill (calvaria) and the outer layer of the dura, which is called the endosteal layer Usually associated with head trauma. Usually answered with subdural hematoma in exams. The classic stem is a young male athlete playing sports, with trauma, who falls and loses unconsciousness, and then gets up with no issues. (Lucid interval) followed by collapse, losing consciousness, and rapidly worsening weakness.
