The dura mater is the tough outermost layer of the three meninges surrounding the brain.
The meninges are protective membranes around the brain and spinal cord. From outside to inside, they are the dura mater, arachnoid mater, and pia mater. The dura mater is dense connective tissue and has two layers in much of the cranial cavity: a periosteal layer attached to the skull and a meningeal layer nearer the brain.
Folds of the cranial dura, including the falx cerebri and tentorium cerebelli, help separate and support major brain compartments. Venous channels called dural venous sinuses form between layers of the cranial dura and drain blood from the brain.
A common mix-up is confusing the dura with the arachnoid mater. The arachnoid is the middle membrane, while cerebrospinal fluid circulates mainly in the subarachnoid space beneath it. The pia mater is the delicate innermost membrane closely following the brain’s surface.