Which layer is the inner layer that covers the arachnoid mater and splits in some areas to form dural folds and venous sinuses?

Which layer is the inner layer that covers the arachnoid mater and splits in some areas to form dural folds and venous sinuses?

• A. Meningeal layer
• B. Periosteal layer
• C. Subarachnoid space
• D. Arachnoid mater

Answer: (A)

The inner layer of the dura mater is the meningeal layer. It lies just under the periosteal layer and closely covers the arachnoid mater. In several areas this layer splits to form dural folds, such as the falx cerebri and tentorium cerebelli, which help partition the brain. Where these layers separate, the spaces become the dural venous sinuses, channels that drain blood from the brain. The outer periosteal layer stays attached to the skull and does not form these sinuses. The subarachnoid space is the area between the arachnoid and pia mater and is not formed by the dura folds. The arachnoid mater is a separate membrane, not the inner layer of the dura.

The inner layer of the dura mater is the meningeal layer. It lies just under the periosteal layer and closely covers the arachnoid mater. In several areas this layer splits to form dural folds, such as the falx cerebri and tentorium cerebelli, which help partition the brain. Where these layers separate, the spaces become the dural venous sinuses, channels that drain blood from the brain. The outer periosteal layer stays attached to the skull and does not form these sinuses. The subarachnoid space is the area between the arachnoid and pia mater and is not formed by the dura folds. The arachnoid mater is a separate membrane, not the inner layer of the dura.