The human brain is present in the cavity of skull called cranium but the brain is not in directly in contact with skull, it is protected by layers of connective tissue called meninges. There are three meninges viz.
1) Dura mater (Hard mother): It is the outermost meninx which is in direct contact with cranium of skull. Below the dura mater there is a space called sub-dural space which is filled with Serous fluid which acts as shock absorber to the brain.
2) Arachnoid mater: It is the middle meninx having blood vessels and it forms Spider web like structure. Below the arachnoid matter there is a space called sub-arachnoid space which is filled with CSF (cerebrospinal fluid) secreted by choroid plexus and ependymal cells of brain. CSF acts as shock absorber as well as protects brain from desiccation.
3) Pia mater (Soft mother): It is thin, innermost meninx which is in direct contact with brain. It is highly vascularised structure.
