The dura mater is the outermost layer of the three protective membranes, known as meninges, that surround the brain and spinal cord. It is a tough, durable membrane that provides a protective barrier against physical impacts and infections. The dura mater is made of dense connective tissue and is closely attached to the inner surface of the skull. In addition to its protective role, the dura mater also contains blood vessels and nerves. It is divided into two layers: the periosteal layer, which is attached to the skull, and the meningeal layer, which covers the brain and spinal cord. These layers help to form structures like the dural sinuses, which drain blood from the brain.