Meninges and blood supply Flashcards
How many layer of meninges are there and what are their names?
3
- Dura mater
- Arachnoid mater
- Pia mater
What are the roles of the meninges?
- Physical protection
- Facilitate flow of CSF
- Provide a framework for blood vessels to supply CNS tissues
Where can the dura mater be distinguished as two separate layers?
- Falx cerebri
- Tentorium cerebelli
Which nerve supplies the dura mater?
CN V = trigaminal
Describe the sub-arachnoid space
It is a true space that has blood vessels running through it and contains CSF.
It is criss-crossed with connective tissue giving a spider web appearance
Where does the pia mater follow and merge?
Follows blood vessels into tissue and merges with tunica adventitia (outer layer of blood vessels)
What is the epidural space in the spinal cord filled with?
Fat and connective tissue
What is a cuff zone?
The point at which meninges stop (after traveling a small distance out with the nerves) and merge with the outside of the nerve
It is easier for drugs to access a nerve at these points
Where is the CSF found in the brain?
- sub-arachnoid space
- ventricles
What is the channel that runs between the 3rd and 4th ventricles?
mesencephalic aquaeduct
Where is the 4th ventricle found?
Caudal to the cerebellum
Where is CSF produced?
Choroid plexi
Where are the two locations of the choroid plexi?
- Between the lateral ventricles and 4th ventricle
2. In the roof of the 4th ventricle
What are the 3 layers of the blood brain barrier?
Endothelial cells have tight junctions
Thick basement membrane
Foot processes of astrocytes
What type of substances can easily pass into the CSF?
Lipid soluble
What are the transporting cells in the blood brain barrier?
Ependymal cells
Where are the 2 sites of CSF sampling?
- Right behind skull at the junction between the occipital bone and first vertebrae
- At the end of the spinal cord where it narrows as there is less tissue
What is the cerebral arterial circle?
Circle of arteries that gives off arteries to supply different bits of the brain
Which part of the brain does the cerebral arterial circle go around?
Hypothalamus
Why is the source of the arterial supply important to know in industry?
In terms of slaughter technique e.g. halal
What are the 2 routes that arterial supply reaches the cerebral arterial circle?
Directly or via rete mirabile
What is the purpose of rete mirable?
Cool down the blood and reduce its pulsation/speed
What is meant by poor collateral circulation in the brain?
Not much interarterial communication
Blockage of an artery means the blood supply to the tissue is stopped e.g. stroke
Where does the spinal cord blood supply branch from?
Vertebral artery and aorta
