Expansion
Dumb Aunts Party
Mnemonic
“DAP”, from the skull inwards:
- D - Dura mater, tough, two layered
- A - Arachnoid mater, avascular and delicate
- P - Pia mater, adherent to the brain surface
The spaces follow the same order, and each has its own haemorrhage:
- Extradural, between skull and dura, arterial
- Subdural, between dura and arachnoid, venous bridging veins
- Subarachnoid, between arachnoid and pia, containing the cerebrospinal fluid and the circle of Willis, so bleeding here is from a berry aneurysm
Cerebrospinal fluid lies in the subarachnoid space, which is why a lumbar puncture enters it and why xanthochromia there confirms subarachnoid haemorrhage.
Expansion
- D - Dura mater, thick outer layer
- A - Arachnoid mater, middle web like layer
- P - Pia mater, thin layer hugging the brain surface