Back تحببات عنكبوتية Arabic Pacchionische Granulation German Granulaciones aracnoideas Spanish Granulation arachnoïdienne French Granulación aracnoide Galician くも膜顆粒 Japanese Granulationes arachnoideae Dutch Araknoidal granulasjon NN Ziarnistości pajęczynówki Polish Грануляции паутинной оболочки Russian
| Arachnoid granulation | |
|---|---|
 Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. ("Arachnoid granulation" label is at top right.) | |
 Arachnoid granulations seen on autopsy, where the dura mater has been removed but the arachnoid mater is left in place. | |
| Details | |
| Identifiers | |
| Latin | granulationes arachnoideae |
| TA98 | A14.1.01.205 |
| TA2 | 5389 |
| FMA | 77760 |
| Anatomical terminology | |
Arachnoid granulations (also arachnoid villi, and pacchionian granulations or bodies) are small protrusions of the arachnoid mater (the thin second layer covering the brain) into the outer membrane of the dura mater (the thick outer layer). They protrude into the dural venous sinuses of the brain, and allow cerebrospinal fluid (CSF) to exit the subarachnoid space and enter the blood stream.
The largest granulations lie along the superior sagittal sinus, a large venous space running from front to back along the center of the head (on the inside of the skull). They are, however, present along other dural sinuses as well.