L-21 Flashcards
What are meninges?
Protective coverings for the brain and spinal chord
How many layers of meninges are there? What are they called?
- 3
- Dura Mater
- Arachnoid Mater
- Pia Mater
Which meningeal layer is closest to the cranium?
Dura Mater
What is Dura Mater
- the outermost layer of the meninges
- dense and fibrous- first line of defence if cranium is injured
- consists of two layers- outer and inner
What are the spaces between the layers of dura mater called?
Venous sinuses
What are the two special features of the dura mater?
- Venous sinuses
- Dura folds
What are dural folds?
Sections of the inner dural layer that separate the major divisions of the brain and provide stability to the brain within the cranium
How many dural folds are there? What are they called
- 3
- Falx cerebri
- Falx cerebelli
- Tentorium cerebelli
What does the Falx Cerebri separate?
- right and left cerebral hemispheres
- on the median plane
What does the Falx cerebelli separate?
Cerebellar hemispheres
- median plane
What does the tentorium cerebelli separate?
- cerebrum from cerebellum
- horizontal plane
- one on each hemisphere?
What are venous sinuses? What do they do?
Collecting veins located where dural layers separate. They collect venous blood from the brain and old CSF after it has cycled through the ventricular system
What is Arachnoid mater?
- meningeal layer beneath the dural mater
- identified by spider like appearance
- does not extend into sulci
- Contains blood vessels within subarachnoid space
WHat are the two special features of the arachnoid mater?
- Subarachnoid space
- Arachnoid granulations
What is the subarachnoid space?
Area between the arachnoid and Pia mater that is filled with CSF
What are arachnoid granulations?
Granulations that perforate the inner dural layer and act as pumps to transport old CSF from the subarachnoid space into the venous sinus
What is Pia Mater?
- the innermost layer of the meninges
- transparent and delicate
- adheres to brain and follows gyro and extends into sulci
- blood vessels of the arachnoid layer sit on top
What is the ventricular system?
A network of interconnected spaces (ventricles) within the brain. Filled with CSF which nourishes and protects the brain and are lined with Ependymal cells which circulate the CSF.
How many ventricles make up the ventricular system? What are their names?
- 4 types, 5 ventricles
- lateral ventricles (2)
- Third ventricle (1)
- Cerebral aqueduct( 1)
- Fourth ventricle (1)
Where are the lateral ventricles located?
One in each cerebral hemisphere
Where is the third ventricle located?
in the diencephalon
Where is the cerebral aqueduct located?
- in the midbrain
- connects third and fourth ventricles
Where is the Forth Ventricle located?
- at the level of the cerebellum
- connects to central canal
What are the roles of the CSF? (2)
- surround the CNS within the subarachnoid space and provide support and cushioning
- transport nutrients and waste
Where is CSF produced?
By choroid plexus in Lateral ventricles
What is the order of the flow of CSF?
- Starts in lateral ventricles (made in choroid plexus)
- Travels to and through third ventricle, cerebral aqueduct, fourth ventricle and enters subarachnoid space
- Flows around brain and spinal chord and exits through arachnoid granulations into venous sinuses
