Subarachnoid
Literally, beneath the arachnoid, the middle of three membranes that cover the central nervous system. In practice, subarachnoid usually refers to the space between the arachnoid and the pia mater, the innermost membrane surrounding the central nervous system.
The subarachnoid space is a potential space. It normally contains cerebrospinal fluid. A subarachnoid hemorrhage is a bleed into this space.
The arachnoid is named for its delicate, spider-web-like filaments that extend from its undersurface through the cerebrospinal fluid in the subarachnoid space to the pia mater. “Arachnoid” comes from the Greek “arachne” meaning spider or cobweb + “eidos” meaning resemblance = spider-web-like.
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A bleeding into the subarachnoid, the space between the arachnoid and the pia mater, the innermost membrane surrounding the central nervous system. Subarachnoid hemorrhage typically occurs when an artery breaks open in the brain, such as from a ruptured aneurysm. This can require emergency neurosurgical procedures.
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A very common cause of a painless bloody eye usually first noticed by somebody else or by the person with it when they look in the mirror. The bleeding results from a break in a small blood vessel in the sclera, the white of the eye. This releases a tiny amount (less than a drop) […]