Cranial and Spinal Meninges

The brain is wrapped by three membranes called meninges.

The outermost cranial dura mater has the periosteal layer adhering to the inner skull surface and the underlying meningeal layer.

The dura mater extends inwards, forming three dural septa: the falx cerebri, the falx cerebelli, and the tentorium cerebelli. They restrict the excessive movement of the brain within the cranium.

The arachnoid mater is the middle meninx and has projections extending into the superior sagittal sinus called the arachnoid granulations. They are essential in absorbing cerebrospinal fluid.

The subarachnoid space containing the CSF separates the arachnoid mater from the innermost meninx — pia mater.

The subarachnoid space helps absorb the external shocks, while the pia mater firmly adheres to the brain, providing additional protection.

Like the brain, three meninges also cover the spinal cord.

They are structurally the same as the cranial meninges, except for the spinal dura, which has only the meningeal layer.

The epidural space between the spinal dura and vertebral column has a network of veins and is filled with fat that provides additional cushion