Meninges and Ventricular System Flashcards
What makes up the meninges?
- Dura mater (outermost layer)
- Arachnoid (middle layer)
- Pia mater (innermost layer)
What are the five features of the dura mater (‘tough mother’)?
- outer most layer of meninges
- dense and fibrous (tough)
- two layers (outer and inner)
- space between the layers forms venous sinuses - only in some places
- inner layer forms dural folds
What are the three features of the dural folds?
- formed from inner layer of dura mater
- separates the major divisions of the brain
- provides stability of the brain within the cranium
What are the three dural folds called and what are their purposes?
- Falx cerebri: separates cerebral hemispheres in the median plane (think saggital but upper)
- Falx cerebelli: separates cerebellar hemispheres in the median plane (thing saggital but lower)
- Tentorium cerebelli: separates cerebrum from cerebellum. horizontal plane (thing transverse
What are the three features of the venous sinus?
- located where the two layers of dura mater separate
- collecting veins
- They collect two things:
1. Venous blood from the brain
2. ‘Old’ CSF after it has cycled through the ventricular system
What are the five features of the arachnoid?
- Layer beneath the dura mater
- layer above pia mater
- Does NOT extend into sulki (‘valleys’)
- Contains 2 special features
1. Subarachnoid space
2. Arachnoid granulations - contains blood vessels (within the subarachnoid space, lying on top of pia mater).
What are the features of the subarachnoid space?
- It is between the arachnoid and the pia mater
- it is filled with cerebrospinal fluid (CSF)
What are the arachnoid granulations?
- Perforate the inner layer of the dura mater
- Transport ‘old’ CSF from subarachnoid space into venous sinus
The CSF is manufactured elsewhere but it puts pressure on the subarachnoid space causing it to flow out of the arachnoid granulation and into the venous sinus.
What are the four features of the pia mater?
- Inner layer of the meninges
- Transparent and delicate
- Blood vessels in arachnoid sit ontop of pia mater
- Adheres to brain and follows gyri and extends into sulci
Describe the structure of the meninges of the spinal cord
It is very similar to in the brain.
From outside in it goes: dura mater, arachnoid mater, pia mater. The subarachnoid space is what the fluid is suspended in.
What are the four features of the ventricular system?
- Network of interconnected ‘spaces’ (= ventricles) within the brain
- Filled with cerebrospinal fluid (CSF), which nourishes and protects the brain
- Spaces lined with ependymal cells which circulate the CSF (waving cilia)
- CSF if produced by the choroid plexus
What is the choroid plexus?
A special type of tissue which is located inside the ventricles (mainly the lateral ones) and produces cerebrospinal fluid (CSF).
What does the ventricular system consist of/what is it made up of?
- 2x Lateral ventricles (one in each cerebral hemisphere)
- Third ventricle (located in the diencephalon)
- Cerebral aqueduct (connects 3rd and 4th ventricles. located in the midbrain)
- Fourth ventricle (located at the level of the cerebellum)
- Central canal (it circulates a small amount of CSF)
What are the four features of cerebrospinal fluid?
- Produced by choroid plexus within the ventricles
- Surrounds the CNS, within subarachnoid space
- Provides support and cushion
- Transports nutrients and waste
What is the circulation path of CSF?
- Starts at lateral ventricles
- 3rd ventricle
- cerebral aqueduct
- 4th ventricle
- subarachnoid space
- within the subarachnoid space it flows around brain and spinal cord
EXIT: through arachnoid granulations into venous sinus.
The ‘old’ CSF will be degraded while the deoxygenated blood will be recycled.
