arachnoid

1. Anatomy. Of or relating to a delicate membrane enclosing the spinal cord and brain.
2. Of, relating to, or resembling arachnids.
3. Covered with or consisting of thin, soft, entangled hairs or fibers resembling those of a cobweb or spider's web.

1. See arachnid.
2. Anatomy. A delicate membrane that encloses the spinal cord and brain and lies between the pia mater and dura mater.

[New Latin arachnoīdēs, from Greek arakhnoeidēs, cobweblike : arakhnē, spider + -oeidēs, -oid.]

1. resembling a spider's web.
2. the delicate membrane interposed between the dura mater and the pia mater, and with them constituting the meninges. Called also arachnoidea.

• cerebral a., arachnoidea cerebri — the arachnoid investing the brain.
• a. cyst — cysts of the pia and arachnoid containing cerebrospinal fluid; may cause gradually increasing pressure on nervous tissue, especially spinal cord, causing ataxia, paresis.
• a. fibroblastoma — see meningioma.
• a. granulations — villous enlargements of the arachnoid that protrude into dural sinuses or diploic veins and serve to drain cerebrospinal fluid. They are conspicuous in the dorsal sagittal sinus of the horse.
• a. membrane — arachnoid; middle layer of the meninges.
• spinal a. — the arachnoid investing the spinal cord.

Look up arachnoid in Wiktionary, the free dictionary.

Arachnoid may refer to:

• Relating to arachnids
• Arachnoid mater, a layer of the meninges, membranes that contain the central nervous system
• Arachnoid (astrogeology), a geological structure found only on the planet Venus

See also

• Arkanoid, an arcade game

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