The Human Brain : From Neurone to Nervous System

MENINGES


  1. The brain and spinal cord are surrounded by cerebro-spinal fluid (CSF) contained within the meninges (meningeal membranes).

  2. The meninges consist of three layers: the (outer) dura mater, arachnoid mater and (inner) pia mater.

  3. Cerebro-Spinal Fluid, manufactured by the Choroid Plexuses, circulates within the sub-arachnoid space, i.e between the arachnoid mater and pia mater. It acts as a cushion to protect the brain.

  4. The meningeal membranes are sensitive to stretch, and pain and headache are common symptoms arising from them. The sensory impulses arising in the meninges also cause reflex spasm of neck and paravertebral muscles, which is an important sign of meningeal irritation.

  5. Blood vessels have to pass through the meninges in order to deliver oxygen, glucose and other substances to the brain. These vessels can be ruptured as a result of head injury, or because of weakness associated with an aneurysm (as in sub-arachnoid haemorrhage) or other pathologies, and the consequences can be life threatening.


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