The extradural (epidural) space is a potential space between the cranial bones and the endosteal layer of the dura mater, which is otherwise adherent to the cranial bone.
The extradural space is a potential space inside the cranial vault and is not normally appreciable unless there is an underlying pathology .
This is in contrast to the epidural space of the spinal cord which contains epidural fat, lymphatics, blood vessels, and nerve roots . The two spaces are not continuous.
Meningeal arteries exist within the cranial extradural space. These include branches of the middle meningeal artery . These vessels may be damaged in trauma and can lead to a collection of blood known as an extradural hematoma.