Intact brain II- Meninges and blood supply Flashcards
Describe the consistency of the brain
Soft like set custard
What is the brain protected by?
- Hair
- Skin
- Skull
- Meninges
What is the skull a collective term for?
- Skin
- Dense connective tissue
- occipito frontal muscle
- Loose connective tissue
- layer of periosteal
What does the subarachnoid space contain?
Cerebrospinal fluid (CNF)
Name the 3 layers of meninges
- Dura mater
- Arachnoid
- Pia mater
Describe the Dura mater
It is a tough fibrous membrane that forms the outer protective later
It can be divided into a periosteal and membranous layers
Where is the periosteal layer found
Tightly adhered to the underside of the skull
Describe the arachnoid
It is a thin delicate avascular layer
It is usually held again the inner layer of the dura mater by pressure in the underlying cerebrospinal fluid
What is the space between the dura mater and the arachnoid called?
It is a sub dural space
Describe the pia mater
It is a delicate vascular layer that is adherent to the surface of the CNS
What is the space between the the arachnoid and the pia mater called?
The subarachnoid space
What is the role of the CNF?
- To protect the CNS
2. To form a water jacket around the CNS
Where do the 3 meninges extend to?
Through then foramen magnum to the spinal cord
What are the 2 layer the dura mater can be split into called?
- The inner meninges layer
2. Outer periosteal layer
Where is the inner meninges layer?
Tightly lines the arachnoid
Where is the cute periosteal layer?
Tightly lines the underlying skull;;
The areas where the meningeal layer and periosteal layer of the dura are called what?
Dural sinuses
Why are dural sinuses important?
They are important in enabling venous blood to be drained from the brain to the internal jugular vein
How are dural sinuses formed?
When the inner meningeal layer comes way from the outer periosteal layer
What do the inner meningeal layers do when they separate from the periosteal layer?
Both the left and right meningeal layer converge and form a partition between the 2 cerebral hemisphere
This is the faix cerebri
What is the sinus above the fix cerebra called?
The superior sagittal sinus
Which veins empty into the superior sagittal sinus?
The superficial veins
The great cerebral vein receives blood from where?
The deep veins of the brain
What does the great cerebral veins empty into?
The straight sinus
Where do the straight sinus and superior sagittal sinus converge into
They converge into the confluence of the sinuses
What comes out of the confluence of sinuses?
The left and tight transverse sinuses
Where do the transverse sinuses run?
They travel laterally along the root of the tentorium cerebelli
What do the transverse sinuses become?
The sigmoid sinuses
Where do the sigmoid sinuses run?
To the jugular veins
Which foramen does the jugular vein pass through?
The jugular foramen
What connects the 2 cerebral hemispheres?
The corpus callosum
Describe the corpus callosum
It is a thick bad of white matter that separates the left and right cerebral hemispheres
Where does the fair cerebri extend from and to?
It extends from the Crista galli anterior to the internal occipital protuberance posterior
What does the fair cerebri give rise to?
The sagittal sinus
What is the tentorium cerebelli?
A horizontal dural fold that separates the occipital folds from the cerebella hemispheres
How is the CNF in the sub arachnoid space recycles into the venous system?
Arachnoid granulations (villi)
What are Arachnoid granulations (villi)
By specialised finger like projections
Name the 2 pairs of arteries that supply blood to the brain
- Internal carotid arteries
2. Vertebral arteries
Describe the path the internal common carotid artery takes to get to the brain
- Common carotid artery bifurcates into the internal and external common carotid arteries
- The internal common carotid artery runs up the neck and passes through the carotid canal to get to the skull
What does the internal common carotid artery do oceanarium its in the brain?
Ir runs slightly anteriorly and gives rise to the middle cerebral artery and forms the circle of willis
Where do the vertebral arteries ascend
Ascend through foramena in the transverse processes of the cervical vertebrae
Then goes into the skull through the foramen magnum on the ventral sept of the medulla oblongata
What happens to the vertebral arteries once they enter the skull?
They fuse together to form the basilar arteries
Where do the basilar arteries run?
Ventral aspect of the pons
Which arteries comes off the vertebral arteries?
- Posterior inferior cerebella artery
2. The Anterior spinal artery
What comes off the vertebral arteries?
The Anterior spinal artery
Where does Anterior spinal artery run
Run cordially down the spinal cord
Which arteries come off the basilar arteries
- The anterior inferior cerebella arteries
- The pontine branches
- Labyrinthine arteries
- The superior cerebella arteries
Name the 3 pairs of arteries that supply the cerebella
- Posterior inferior cerebella artery
- The anterior inferior cerebella arteries
- The superior cerebella arteries
What does the basilar artery bifurcate into?
The posterior cerebral arteries
How does the internal carotid artery become the middle cerebral artery
It runs slight anterior then quickly runs laterally to become the middle cerebral artery
What foe the internal carotid artery become?
The middle cerebral artery
What connect the middle cerebral artery to the posterior cerebral artery?
2 slender arteries called posterior communication arteries
Name the 3 pairs of arteries that supply the cerebrum
- The posterior cerebral arteries
- The middle cerebral artery
- The anterior cerebral artery
Which arteries come off anteriorly from the middle cerebral artery?
The anterior cerebral artery these extend forwards and then travel over the corpus calosum
What percentage of the blood to the brain is supplied by the vertebral arteries?
30%
What percentage of the blood to the brain is supplied by the common carotid arteries?
70%
What does the posterior inferior cerebella artery supply?
The posterior inferior portion of the cerebellum
What does the anterior inferior cerebella artery supply?
The anterior inferior portion of the cerebellum
What does the superior cerebella artery supply?
The superior portion of the cerebellum
Where does bifurcation of the basilar artery occur?
At the point midbrain section
What do the anterior cerebral arteries supply?
Majority of the medial aspect of the cerebral hemisphere
And about a cm of the lateral surface
What do the middle cerebral arteries supply?
Majority of the lateral surface
What do the posterior cerebral arteries supply?
Majority of the underside of the temporal lobe
And the majority of the temporal lobe
What is the faix cerebri?
The partition formed by the convergence of the left and right meningeal layers in the dura
This separates the 2 cerebral hemispheres
Where do deep veins drain into?
The great cerebral vein
Where is the superior sagittal sinus found?
Above the faix cerebri
What empties into the straight sinus?
The great cerebral vein
What is the confluence of the sinuses?
Where the straight sinus and superior sagittal sinus converge into
Where do the superficial veins drain into?
The superior sagittal sinus
What to the left and right transverse sinuses receive blood from?
The confluence of sinuses
Which sinuses empty into the jugular veins?
The sigmoid sinuses
