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Contributors:Pauline Rowsome, BSc (Hons), Tanner Marshall, MS, Sam Gillespie, BSc, Jake Ryan, Filip Vasiljević, MD
So, an epidural hemorrhage is when there’s bleeding above the dura mater.
CSF is a clear, watery liquid which is pumped around the spinal cord and brain, cushioning them from impact and bathing them in nutrients.
The outer membrane, the dura mater consists of two layers.
The internal layer of the dura mater lies above the arachnoid mater - the two are separated by the subdural space.
The external layer of the dura mater adheres to the inner surface of the skull.
These two layers of the dura mater travel together, but at certain spots, the internal layer of the dura mater separates from the external one to form the meningeal folds.
The meningeal folds help divide the sections of the brain like the falx cerebri which separates the two hemispheres of the cerebrum, and the tentorium, which covers the cerebellum and separates it from the cerebrum.
Between the external layer of the dura mater and the inner surface of the skull, there are arteries that supply meninges.
The most common cause of epidural hemorrhage is a head trauma which might happen after tripping and falling in a bathtub.
The meningeal arteries are protected by the skull but can be damaged by a serious head trauma.
The most common site is at the pterion which is the spot where the frontal, parietal, temporal and sphenoid bones join together.
This section of the skull is relatively thin and it’s located right above the middle meningeal artery.
When a blood vessel is damaged and there’s active bleeding, it’s called a hemorrhage, and the collection of blood that results is called a hematoma.
In the case of an epidural hemorrhage, once a meningeal artery is torn, blood will pool between the skull and the external layer of the dura mater, separating it from the inner surface of the skull.
The blood builds up between the skull and the outer layer of the dura mater but cannot cross the suture lines where the dura mater adheres more tightly.
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