Dura

The outermost, toughest, and most fibrous of the three membranes (meninges) covering the brain and the spinal cord. Dura is short for dura mater (from the Latin for hard mother). Also called the pachymeninx (singular) or pachymeniges (plural).

Epidural means outside the dura. An accumulation of blood outside the dura is an epidural hematoma. Subdural means under the dura. A bleed under the dura may result in a subdural hematoma.