CRANIAL MENINGIES
The cranial meninges protect and support the brain. The meninges are composed of 3 concentric layers of connective tissue layers.
1. Dura matter 2. Arachnoid matter 3. Pia matter
From superficial to deep:
1. Skull 2. Endosteum 3. Dura mater
4. Subdural space 5. Arachnoid mater
6. Arachnoid trabeculae 7. Subarachnoid space 8. Pia mater 9. Brain
Dura Mater
The dura mater is fused with the skull. It is a very thick, dense, moderately elastic layer. It can be divided into 2 layers; the outer fibrous layer is fused with the skull and makes up the endosteum of the cranium. The inner serous layer surrounds the brain and in regions separates away from the outer layer to formmultiple venous sinus. These spaces are filled with venous blood returning to the heart from the brain.
The subdural space lies between the dura mater and arachnoid mater.
Arachnoid Mater
Second meningeal layer, the arachnoid mater is a thin filmy membrane that lies against the inner surface of the dura mater. It extends over the brain surface and convolutions. Within the arachnoid layer are arachnoid trabeculae, which are attached to the pia mater. This is what creates the subarachnoid space. The subarachnoid space contains CSF which helps support the brain and spinal cord and acts as a shock absorbing cushion.
The subarachnoid space lies between the arachnoid mater and pia mater.
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