- Subarachnoid space
Name = Subarachnoid space
Latin = spatium subarachnoideum, cavum subarachnoideale
GraySubject = 193
GrayPage = 876
Caption = Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. ("Subarachnoid cavity" visible at left.)
Caption2 = Diagrammatic transverse section of the medulla spinalis and its membranes. (Subarachnoid cavity labeled center.)
MeshName = Subarachnoid+Space
MeshNumber = A08.186.566.166.686
DorlandsPre = s_16
DorlandsSuf = 12746651
central nervous system, the subarachnoid cavity (subarachnoid space) is the interval between the arachnoid membraneand pia mater.
It is occupied by a spongy tissue consisting of
trabeculæ(delicate connective tissue filaments that extend from the arachnoid mater and blend into the pia mater) and intercommunicating channels in which the cerebrospinal fluidis contained.
This cavity is small on the surface of the hemispheres of the
brain. On the summit of each gyrusthe pia mater and the arachnoid are in close contact, but in the sulci between the gyri, triangular spaces are left, in which the subarachnoid trabecular tissue is found. Whilst the pia mater closely follows the surface of the brain and dips into the sulci, the arachnoid bridges across them from gyrus to gyrus.
At certain parts of the base of the brain, the arachnoid is separated from the pia mater by wide intervals, which communicate freely with each other and are named
subarachnoid cisternæ; in these the subarachnoid tissue is less abundant. The subarachnoid space is the location of the interface between the vascular tissue and the cerebrospinal fluidand is active in the blood brain barrier.
The arachnoid mater continues down the
spinal cordtoo, and the subarachnoid layer with it. It serves a similar function in the spinal cord as it does in the brain.
* [http://instruct.uwo.ca/anatomy/530/SagSin.gifDiagram at uwo.ca]
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