arachnoid mater

anatomy

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July 21, 2026

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The arachnoid mater is one of the three protective membranes, known as the meninges, that surround the brain and spinal cord. It is a thin, transparent membrane situated between the pia mater and the dura mater. The arachnoid does not follow the brain's surface contours, appearing more like a loose sac. Fine filaments, called arachnoid trabeculae, connect it to the pia mater through the subarachnoid space, which contains cerebrospinal fluid (CSF). Together, the pia mater and arachnoid are referred to as the leptomeninges. The primary role of the meninges and CSF is to protect the central nervous system.12

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epidural hematoma
Anatomy
The second layer, the arachnoid mater, covers the brain and pia mater but does not follow the contour of the involutions of the brain. The outermost layer, the dura mater, provides a thicker and tougher layer of protection.
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The second layer, the arachnoid mater, covers the brain and pia mater but does not follow the contour of the involutions of the brain. The outermost layer, the dura mater, provides a thicker and tougher layer of protection.
Read More

meninges
Pia mater and arachnoid
…the subarachnoid space is the arachnoid, a thin, transparent membrane. It is composed of fibrous tissue and, like the pia mater, is covered by flat cells also thought to be impermeable to CSF. The arachnoid does not follow the convolutions of the surface of the brain and so looks like…
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…the subarachnoid space is the arachnoid, a thin, transparent membrane. It is composed of fibrous tissue and, like the pia mater, is covered by flat cells also thought to be impermeable to CSF. The arachnoid does not follow the convolutions of the surface of the brain and so looks like…
Read More