Meninges Flashcards
Meninges
protective covering for the brain
3 layers of cranial meninges and spinal cord meninges
- dura mater
- arachnoid
- pia mater
Dura mater (5 features)
- outer-most layer of meninges
- dense and fibrous - tough
- two layers; outer and inner - mostly stuck together
- space between layers forms venous sinuses - only in some places
- inner layer forms the dural folds
Arachnoid (5 features)
- layer beneath the dura mater
- layer above the pia mater
- does not extend into the sulci
- contains blood vessels (lying on top of pia mater)
Pia mater (4 features)
- inner layer of the meninges
- transparent and delicate
- blood vessels in arachnoid sit on top of pia mater
- adheres to brain and follows gyri and extends into sulci
Dura mater (2 components)
Dural folds
Dural venous sinus
Arachnoid space (2 components)
Subarachnoid space
Arachnoid granulations
3 dural folds
Falx cerebri
Falx cerebelli
Tentorium cerebelli
Features of dural folds (3)
- formed inner layer of dura mater
- separate major divisions of brain
- provide stability of the brain within cranium
Features of dural venous sinus (3)
- located where the two layers of dura mater separate
- collecting spaces
- collect: venous blood from the brain & ‘old’ CSF after it has cycled through the ventricular system
Dural folds:
Falx cerebri
separates cerebral hemispheres
median plane
Dural folds:
Falx cerebelli
separates cerebellar hemispheres
median plane
Dural folds:
Tentorium cerebelli
separates the cerebrum from the cerebellum
horizontal plane
Arachnoid space:
Subarachnoid space
- between the arachnoid and the pia mater
- filled with cerebrospinal fluid (CSF) - liquid gel layer that surrounds and protects the brain
Arachnoid space:
Arachnoid granulations
- perforate the inner layer of dura mater
- transport ‘old’ CSF from subarachnoid space into venous sinus
Ventricular system (4 features)
- Network of interconnected ‘spaces’ (ventricles) within the brain
- filled with (CSF), which nourishes and protects the brain
- spaces lined with ependymal cells, which circulate the CSF (waving cilia)
- CSF is produced by the choroid plexus
Lateral ventricles
- 2
- one in each cerebral hemisphere
- C-shaped structure that follows the shape of the cerebrum
Third ventricle
- 1
- located in the diencephalon
Cerebral aqueduct
- 1
- connects the 3rd ventricle to the 4th ventricle
- located in the midbrain
Fourth ventricle
- 1
- located at the level of the cerebellum
CerebroSpinal Fluid (CSF) (4 features)
- surrounds the CNS, within subarachnoid space
- provides support and cushion
- transports nutrients and waste
- produced by choroid plexus within the ventricles
CSF circulation path
starts at lateral ventricles —> 3rd ventricle —> cerebral aqueduct —> 4th ventricle —> subarachnoid space (within the subarachnoid space it flows around the brain and spinal cord) —> exits through arachnoid granulations into venous sinus
