Meninges - Anatomy & Physiology

Diagram of the meninges. Sourced from WikiMedia Commons, attributed to http://training.seer.cancer.gov/module_anatomy/unit5_3_nerve_org1_cns.html

• The CNS is surrounded by several layers of tissue.
  1. Bone layer
     • E.g. the skull and the vertebrae.
  2. Dura-arachnoid layer.
     • Composed of the dura mater and arachnoid layer in close opposition.
     • Adhered to the skull in the calvaria.
  3. Pia mater.
• The epidural space lies between the bone layer (skull or vertebrae) and the dura-arachnoid layer.
  • Local anaesthetic is injected here in epidural anaesthesia.
    • E.g. when calving cows.
• The sub-arachnoid space lies between the arachnoid layer and the pia mater.
  • CSF filled.
  • This is where myelographic contrast medium is injected.