1. 1- Dura Mater 2- Arachnoid Mater 3- Pia Mater
The dura mater is the dense, fibrous outermost meningeal covering. It consists of an outer periosteal layer, and an inner meningeal layer. The outer layer of the dura mater is closely applied to the cranial bone as periosteum.
2- Arachnoid Mater
The middle element of the meninges is the filmy and vulnerable arachnoid mater, so named because of its spider web-like appearance. It lies deep to and flush with the inner dura, and adheres to the dura via a series of tight junctions. The arachnoid mater is separated from the deeper pia mater by the subarachnoid space, which is filled with CSF.
3- Pia Mater
The pia mater is a thin vascular layer of fibrous connective tissue.
It is inseparable from the surface of the brain and cord, and is pierced by the blood vessels that travel to the brain and spinal cord.
The subarachnoid space separates the pia and arachnoid layers, with the pia mater loosely connected to the arachnoid mater.

8. Indications
Stroke
Acute Bleed, Severe Headache, Subarachnoid Hemorrhage,
Brain Tumor, Suspected Brain Tumor
CNS Infection, Abscess, Meningitis, AIDS
Pituitary Tumor
Pediatric Anomaly, Pediatric Developmental Delay
Known Aneurysm