arachnoid mater

(redirected from Arachnoid layer)
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a·rach·noid mat·er

[TA]
a delicate fibrous membrane forming the middle of the three coverings of the central nervous system. In life, the arachnoid (specifically the arachnoid barrier cell layer) is tenuously attached to the externally adjacent dura mater (specifically the dural border cell layer), and no natural space occurs at the dura-arachnoid interface. Thus, in a spinal puncture, dura mater and arachnoid are penetrated simultaneously as if a single layer. Separation of the arachnoid mater from the dura mater (usually through the dural-border cell layer) may result from traumatic or pathologic processes creating what is commonly, but incorrectly, called a subdural hematoma. The arachnoid mater is named for the delicate, spiderweblike filaments that extend from its deep surface, through the cerebrospinal fluid of the subarachnoid space, to the pia mater. See: cranial arachnoid mater, spinal arachnoid mater.
See also: leptomeninx.

arachnoid membrane

The increasingly preferred term for the weblike membrane covering the brain that lies between the outer (and much thicker) dura mater and the deeper pia mater, from which it is separated by the subarachnoid space through which CSF flows and is absorbed by the arachnoid granulations.

a·rach·noid mat·er

(ă-rak'noyd mā'tĕr) [TA]
A delicate fibrous membrane forming the middle of the three coverings of the central nervous system. In life the arachnoid (specifically the arachnoid barrier cell layer) is tenuously attached to the externally adjacent dura mater (specifically the dural border cells) and there is no naturally occurring space at the dura-arachnoid interface. Thus, in a spinal puncture, dura mater and arachnoid are penetrated simultaneously as if a single layer. Separation of the arachnoid mater from the dura mater (usually through the dural border cell layer) may result from traumatic or pathologic processes creating what is commonly, but quite incorrectly, called a subdural hematoma. The arachnoid mater is named for the delicate, spiderweblike filaments that extend from its deep surface, through the cerebrospinal fluid of the subarachnoid space, to the pia mater.
Synonym(s): arachnoidea mater [TA] , arachnoid membrane, arachnoidea, arachnoides.
[G. arachnē, spider, cobweb, + eidos, resemblance]

arachnoid mater

See ARACHNOID.

Arachnoid mater

One of three membranes that encase the brain and spinal cord. The arachnoid mater is the middle membrane.

Patient discussion about arachnoid mater

Q. What is the treatment for an arachnoid cyst? My 15 year old son has just been diagnosed with an arachnoid cyst. What is the treatment? Is an operation necessary?

A. An operation is not always necessary, it depends on the size and location of the cyst. I suggest you take your son to a neurologist or a neurosurgeon for further consult.

Q. info on arachnoid cyst in the right posterior fossa

A. Basically it's like a small sac filled with fluid. The problem is that the skull is a rigid closed space, which means that if there's something other than the brain, it'll occupy space, usually on expense of the brains' space. These kinds of problems are often referred to as "space occupying lesion".

It's usually congenital (i.e. develops during pregnancy), and even when it cause symptoms they develop slowly.

YOu can read more here (http://en.wikipedia.org/wiki/Arachnoid_cyst)

Q. Is there any problem, if an arachnoid cyst ,2cmx1.5cm size, rostral to cerebellar region left untreated? symptoms: repeated headaches, twitching of muscles, tiredness

A. An arachnoid cyst that leads to symptoms usually needs treatment. Mild symptoms as you suggested are ok to left untreated however gradual onset of new symptoms may arise such as seizures, paralysis and other complications, therefore once symptoms occur one should consider treatment.

More discussions about arachnoid mater
References in periodicals archive ?
The nerves then follow a relatively long intra-cranial route which first courses through different regions of the sub-arachnoid space between the brain and the arachnoid layer of its covering membranes (meninges), sometimes close to major arteries running in this space near the anterior brainstem surface.
7) It has been suggested that post-traumatic changes can lead to pressure increases that foster an environment suitable for arachnoid layer separation that leads to cyst formation.