The human brain is protected by the skull. Inside the skull, there are cranial meninges that cover the brain. The cranial meninges are made up of three layers, namely – Dura mater (outer layer), Arachnoid (middle layer) and Pia mater (inner layer which is in contact with the brain). Dura mater is a thick, tough, fibrous membrane. Arachnoid is a membrane with a spider-like structure. The parameter is a very thin, delicate and vascular membrane. The space between dura mater and arachnoid is called subdural space. The space between arachnoid and parameter is called subarachnoid space. It is filled with cerebrospinal fluid, which acts as a cushion for CNS from shock.