Meninges

The meninges (singular meninx) are the system of membranes that contain the central nervous system. It consists of three layers, the dura mater, the arachnoid mater, and the pia mater.

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• The pia or pia mater is a very delicate membrane. It is closest to the brain or the spinal cord. As such it follows all the minor contours of the brain (gyri and sulci).
• The middle element of the meninges is the arachnoid mater, so named because of its spider web-like appearance.
• The dura mater is a thick, durable membrane, closest to the skull.

The arachnoid and pia mater are sometimes together called the leptomeninges.

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The subarachnoid space is the space that normally exists between the arachnoid and the pia.

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Normally, the dura mater is attached to the skull in the head, or to the bones of the vertebral canal in the spinal cord. The arachnoid is attached to the dura mater, and the pia mater is attached to the central nervous system tissue. When the dura mater and the arachnoid separate through injury or illness, the space between them is the subdural space.

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A subdural hematoma is, therefore, a separation of the arachnoid from the dura mater. The small veins that connect the dura mater and the arachnoid are torn, and blood can leak into this area. Other medical conditions that affect the meninges include meningitis, a viral or bacterial infection.

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Membrane: A membrane is a thin, typically planar structure or material that separates two environments. Because it sits between environments or phases and has a finite volume, it can be referred to as an interphase rather than an interface. Membranes selectively control mass transport between the phases or e...

Central nervous system: The central nervous system (CNS) represents the largest part of the nervous system. Together with the peripheral nervous system, it has a fundamental role in the control of behaviour....

Dura mater: The dura mater (from the Latin "hard mother") is the tough and inflexible outermost of the three layers of the meninges (the other two being the pia mater and the arachnoid mater). It protects the brain, spinal cord and forms various structures within the cranial cavity. Around the spinal cord it fo...