Anatomy of Meninges(Anatomy)

By: kd ( learning something new ) 1Topic: meninges

Sub-topic: Anatomy of Meninges

2The Meninges:Membrane covering brain and spinal cord.Consists of 3 membranes :Dura mater Arachnoid mater Pia mater

3Duramater :Outermost layer, Thick , dense and elastic membrane BilaminarEndosteal layer (outer)Meningeal layer (inner) - these are closely united except along central lines where they separate to form venous sinuses. -Layers Falx cerebriFalx cerebelliTentorium cerebelliDiaphragma sellae

42. Arachnoid Mater:Lying below duramater (externally).Separated from duramater by a potential space, the subdural space.Separated from piamater by subarachnoid space.

53.Piamater :Innermost layer, Vascular membrane covered by mesothelial cells.Closely invest the brain, covering the gyri, descending into the deepest sulci and closely applied to the cortical surface.Forms Tela Choroidea .Tela Choroida fuse with ependyma to form the choroid plexus.

6Bacterial Meningitis:(clinical correlated_) - Infection of the arachnoid membrane , subarachnoid space , and CSF by bacteria.

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Route:

7Infection may spread from an adjacent infected area such as sinusitis , otitis media , mastoiditis Or, from the environment through a penetrating injury or congenital defect such as menigomyelocoele. Commonly from hematogenous dissemination of bacteria.

summary8

Meninges of spinal cord9

Dura Mater

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The dura mater is theoutermostlayer of the meninges, lying directly underneath the bones ofvertebral column

Arachnoid Mater

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The arachnoid mater is the middle layer of the meninges, lying directly underneath the dura mater. It consists of layers of connective tissue, isavascular, and does not receive any innervation.Underneath the arachnoid is a space known as thesub-arachoid space. It contains cerebrospinal fluid, which acts to cushion the brain. Small projections of arachoid mater into the dura(known asarachnoid granulations)allow CSF to re-enter the circulation via the dural venous sinuses.

Pia mater12The pia mater is located underneath the sub-arachnoid space. It is very thin, andtightly adheredto the surface of the brain and spinal cord. It is the only covering to follow the contours of the brain (the gyri and fissures).

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