Meninges = membranes covering the brain and spinal cord
    Arachnoid mater
    Pia mater

    Two layers of dense fibrous tissue
    Outer layer takes the place of periosteum on the inner surface of the skull
    Inner layer covers the brain
    Forms a partition between the two cerebral hemispheres called the falx cerebri
    Between the cerebellar hemispheres - falx cerebelli
    Between the cerebrum and cerebellum - tentorium cerebelli
    Venous blood from the brain flows through the venous sinuses between the layers of dura mater.
    Falx cerebri forms the superior sagittal sinus
    Tentorium cerebelli forms the straight and and transverse sinuses

    Spinal Dura mater
    Foms a loose sheath around the spinal cord
    Extends from the foramen magnum to the S2 vertebra
    Then it invests the filum terminale
    Fuses with the periosteum of the coccyx
    It is separated from the periosteum of the vertebrae and ligaments within the neural canal by the epidural space.

    Arachnoid mater
    Middle layer of the three membranes covering the brain and spinal cord
    Separated from the dura mater by the subdural space and from the pia mater by the subarachnoid space
    Subarachnoid space contains the cerebrospinal fluid
    Covers the spinal cord also and ends by merging with the dura mater at the level of S2
   Pia mater
    Inner most layer of the meninges
    Fine connective tissue
    Contains minute blood vessels
    Closely invests the brain
    Completely covers the convolutions
    Dips into fissures
    Invests the spinal cord
    Beyond the end of the spinal cord continues as the filum terminale
    Pierces arachnoid mater and with dura mater fuses with periosteum of the coccyx

    Applied anatomy :
    epidural space - epidural anaesthesia
    Subarachnoid space of the spinal canal - spinal anaesthesia
    Inflammation : meningitis - pyogenic; tuberculous

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