The dura is the outermost layer of the three layers of meninges that surround the brain and the spinal cord. The dura is composed of two layers. The outer superficial layer lines the inner side of the skull and the deeper layer overlies the brain. The deeper layer is the actual dura as most consider it. The two dural layers enclose spaces called the dural sinuses that drain venous blood. The dura extends down to the spinal cord.