Arachnoid

 

A clear membrane with fine strands (resembles a spider's web -- arachnoid = related to spider) that surrounds a cap of cerebrospinal fluid that covers the pial surface of the entire central nervous system.


Below the arachnoid lies the subarachnoid space.  The cerebral arteries run through the subarachnoid space.

 

Arachnoid villi

Arachnoid cyst

Adhesive arachnoiditis

 
Figure:  Arachnoid membrane overlying the cerebral (temporal, frontal, parietal lobes) cortex glistening under the OR lights frontotemporoparietal craniotomy.

Mueller MD Hamburg

 

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