Arachnoid mater

Arachnoid mater

Infobox Brain
Name = PAGENAME
Latin =
GraySubject = 193
GrayPage = 876


Caption = The medulla spinalis and its membranes.


Caption2 = Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc.
IsPartOf = Meninges
Components =
Artery =
Vein =
BrainInfoType = ancil
BrainInfoNumber = 561
MeshName = Arachnoid
MeshNumber = A08.186.566.166
DorlandsPre = a_56
DorlandsSuf = 12149123
The arachnoid mater is one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space.

The delicate, spiderweb-like (therefore the name) arachnoid layer, attached to the inside of the dura, surrounds the brain and spinal cord but does not line the brain down into its sulci (folds). Cerebrospinal fluid flows under this membrane in the subarachnoid space, which is full of the delicate fibres of the arachnoid extending down to attach to the pia mater.

The portions covering the brain and spinal cord are called "arachnoidea encephali" and "arachnoidea spinalis", respectively.

The arachnoid and pia mater are sometimes considered as a single structure, the "leptomeninx", or the plural version, "leptomeninges". (Lepto- from the root meaning "thin" in Greek). Similarly, the dura in this situation is called the "pachymeninx".

Etymology

"Arachnoid" is from a Greek root, and means "cob web like". The "mater" designation (meaning "mother" in Latin) is borrowed from the "dura mater" and "pia mater", which were Latin translations of Arabic terms. While "mater" does not technically belong with the arachnoid layer, it has nevertheless been adopted by it for uniformity with the other meninges, and "arachnoid mater" is currently the Terminologia Anatomica international standard.


=Additional

References

* Orlando Regional Healthcare, Education and Development. 2004. [http://www.orlandoregional.org/pdf%20folder/overview%20adult%20brain%20injury.pdf "Overview of Adult Traumatic Brain Injuries."] Retrieved on 2008-01-16.

External links

*
* [http://www.upei.ca/histology/assets/images/w-spinal-2.jpgSlide]

ee also

* Arachnoid cyst


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Look at other dictionaries:

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  • arachnoid mater — see arachnoid * * * arach·noid ma·ter (ə rakґnoid maґtər) (mahґter) arachnoidea mater …   Medical dictionary

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  • arachnoid — SYN: a. mater. [G. arachne, spider, cobweb, + eidos, resemblance] a. of brain SYN: cranial a. mater. cranial a. mater [TA] that portion of the a. that lies within the cranial cavity and surrounds the …   Medical dictionary

  • Arachnoid — The word Arachnoid means pertaining to or resembling an arachnid or spider. It may also refer to:* Arachnoid mater, one of the three layers of the meninges, a system of membranes that contain the central nervous system. * Arachnoid (astrogeology) …   Wikipedia

  • arachnoid barrier cell layer — the outer layer of the cranial and spinal arachnoid mater, immediately internal to the dura mater and loosely attached to the dural border cell layer by occasional cell junctions. Its cells have tightly apposed cell membranes and are connected to …   Medical dictionary

  • arachnoid — 1. adjective a) Relating to spiders. b) Relating to or resembling spider webs. 2. noun a) An arachnid b) The arachnoid mater, the middle layer of t …   Wiktionary

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