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