Central nervous
system
1) Coverings of the
brain and Dural venous sinuses
MENINGES are connective tissue membrane covering brain
and spinal cord.
There are three layers of meninges
Dura mater
Arachnoid mater
Pia mater
DURA MATER – outermost covering, fibrous membrane and made
up of two layers.
Outer -endosteal layer Inner -meningeal layer
OUTER ENDOSTEAL LAYER - Meningeal blood vessel pass deep to this
layer, it forms the inner periosteum of the skull bones.
Mostly the endosteal and meningeal layer are fused together but at
certain places these two layers are separated ,this space with
endothelial lining
drains venous blood from the brain and meninges called dural venous
sinuses.
INNER MENINGEAL LAYER-this layer projects inwards to form folds
called Dural folds.
DURAL FOLDS they divide the cranial cavity into compartments
, 1.FALX CEREBRI -it is a sickle shaped fold in the median sagittal plane
and occupies in the median longitudinal fissure of the cerebrum.
2.TENTORIUM CEREBELLI-it is a broad tent shaped fold placed
horizontally between cerebrum above and cerebellum below .
3. DIAPHRAGM SELLAE- it is a horizontally placed dural fold forming the
roof of pituitary fossa (sella turcica) ,traversed in the centre by the
stalk of the pituitary gland.
4.FALX CEREBELLI- this fold lies below the tentorium cerebelli .
These meningeal folds are supplied by blood vessels and nerve fibres.
ARACHNOID MATER – it is the middle layer separated from the dura
mater by a potential space called subdural space and separated from
the inner pia mater by subarachnoid space .
SUBARACHNOID CISTERNS – these are enlarged subarachnoid spaces
at the base of the brain and around the brainstem, these cisternae are
traversed by cerebral blood vessels.
1. Cerebellomedullary cistern ( cisterna magna ): lies between the
dorsal surface of medulla and inferior surface of cerebellum.The CSF
from the 4thventricle escapes into this cistern through an opening called
foramen of magendie.
2.Cisterna pontis: lies on the ventral aspect of the pons . The CSF from
the 4thventricle escapes into this cistern through two lateral apertures
called foramen of Luschka.
3.Interpeduncular cistern: lies at the base of the brain at the
interpeduncular fossa.
ARACHNOID GRANULATIONS- these granulations are made up of
numerous arachnoid villi. Arachnoid villi serves as sites where the CSF
system
1) Coverings of the
brain and Dural venous sinuses
MENINGES are connective tissue membrane covering brain
and spinal cord.
There are three layers of meninges
Dura mater
Arachnoid mater
Pia mater
DURA MATER – outermost covering, fibrous membrane and made
up of two layers.
Outer -endosteal layer Inner -meningeal layer
OUTER ENDOSTEAL LAYER - Meningeal blood vessel pass deep to this
layer, it forms the inner periosteum of the skull bones.
Mostly the endosteal and meningeal layer are fused together but at
certain places these two layers are separated ,this space with
endothelial lining
drains venous blood from the brain and meninges called dural venous
sinuses.
INNER MENINGEAL LAYER-this layer projects inwards to form folds
called Dural folds.
DURAL FOLDS they divide the cranial cavity into compartments
, 1.FALX CEREBRI -it is a sickle shaped fold in the median sagittal plane
and occupies in the median longitudinal fissure of the cerebrum.
2.TENTORIUM CEREBELLI-it is a broad tent shaped fold placed
horizontally between cerebrum above and cerebellum below .
3. DIAPHRAGM SELLAE- it is a horizontally placed dural fold forming the
roof of pituitary fossa (sella turcica) ,traversed in the centre by the
stalk of the pituitary gland.
4.FALX CEREBELLI- this fold lies below the tentorium cerebelli .
These meningeal folds are supplied by blood vessels and nerve fibres.
ARACHNOID MATER – it is the middle layer separated from the dura
mater by a potential space called subdural space and separated from
the inner pia mater by subarachnoid space .
SUBARACHNOID CISTERNS – these are enlarged subarachnoid spaces
at the base of the brain and around the brainstem, these cisternae are
traversed by cerebral blood vessels.
1. Cerebellomedullary cistern ( cisterna magna ): lies between the
dorsal surface of medulla and inferior surface of cerebellum.The CSF
from the 4thventricle escapes into this cistern through an opening called
foramen of magendie.
2.Cisterna pontis: lies on the ventral aspect of the pons . The CSF from
the 4thventricle escapes into this cistern through two lateral apertures
called foramen of Luschka.
3.Interpeduncular cistern: lies at the base of the brain at the
interpeduncular fossa.
ARACHNOID GRANULATIONS- these granulations are made up of
numerous arachnoid villi. Arachnoid villi serves as sites where the CSF
