Lecture 21 Flashcards
What are the three layers of the meninges?
- dura mater
- arachnoid
- pia mater
What are the features of the dura mater?
- outer-most layer
- dense+fibrous
- 2 layers (outer + inner)
- space between layers forms venous sinuses
- inner layer forms dural folds
What are the features of the dural folds?
- formed from inner layer of dura mater
- seperate major divisions of the brain
- provide stability of the brain within the cranium
What are the 3 dural folds and their purpose?
Falx cerebri - seperates cerebral hemispheres in the median plane
Falx cerebelli - seperates cerebellar hemispheres in median plane
Tentorium cerebelli - seperates cerebrum from cerebellum in horizontal plane
What are the features of the venous sinus?
- located where 2 layers of dura mater separate
- collecting veins
- collect venous blood + old CSF
What are the features of the arachnoid?
- layer beneath dura mater
- layer above pia mater
- does not extend into sulci
- contains 3 special features (subarachnoid space, arachnoid granulations, arachnoid trabeculae)
- contains blood vessels
What is the subarachnoid space?
- space between arachnoid and pia mater
- outer layer of arachnoid bound with tight junctions
- filled with CSF
What are arachnoid granulations?
- perforate inner layer of dura mater
- transport old CSF from subarachnoid space to venous sinus
What are the features of the pia mater?
- inner layer of meninges
- transparent + delicate
- blood vessels in arachnoid sit on top
- adheres to brain and follows gyri and extends into sulci
What are the features of the ventricular system?
- network of interconnected spaces (ventricles) within the brain
- filled with CSF
- spaces lined with ependymal cells which circulate CSF via cillia
- CSF produced in choroid plexus
What are the different ventricles of the brain and their locations?
Lateral ventricles -one in each cerebral hemisphere
Third ventricle - diencephalon
Cerebral aqueduct - midbrain
Fourth ventricle - at level with cerebellum
What are the features of CSF?
- produced by choroid plexus within ventricles
- surrounds CNS within subarachnoid space
- provides support + cushioning
- transports nutrients and waste
What are the features of the choroid plexus?
- epithelial cells make up blood/CSF barrier
- many immune cells
- villi to push CSF around
What is circulation path of CSF?
lateral ventricle -> 3rd ventricle -> cerebral aqueduct -> 4th ventricle -> subarachnoid space
Exits through arachnoid granulations to venous sinus
