Meningeal layers, dural folds, dural venous sinuses Flashcards
What are the meninges?
Membranous layers that surround the brain
How many meninges are there?
Three
What are the meninges called? How are they arranged?
Dura - superficial
Arachnoid - middle
Pia - deep
How are the dura, arachnoid and pia meninges related to each other?
Are close to each other
small spaces in between
What are the small spaces between the meninges called?
Sub-dural space - between dura and arachnoid
Sub-arachnoid space - between arachnoid and pia
What are the sub-dural and sub-arachnoid spaces called potential spaces?
Because fluid can accumulate there
What fluids are most likely to accumulate in the sub-dural and sub-arachnoid spaces?
Blood
CSF
What type of tissue is the dura made out of?
Fibrous connective tissue
How many layers does the dura have?
Two
What are the layers of the dura?
Periosteal layer
Meningeal layer
What is the periosteal layer of the dura?
Endosteum of inner surface of neurocranium
What is the meningeal layer of the dura?
Layer superficial to arachnoid
What layers of the meninges cannot be peeled off? Why?
Pia, equivalent to the visceral layer of a serous membrane
Periosteal layer of dura, forms part of the neurocranium bone layers
How do the periosteal layer and meningeal layer of the dura relate to each other?
Are close to each other
apart from at dural folds, dural venous sinuses
What are dural folds?
Double-folds of the meningeal layer of the dura
against the periosteal layer
What is the function of the dural folds?
Divide the brain into different sections
and hold those different sections in their places
What are the main dural folds?
Falx cerebri
Tentorium cerebelli
Where is the falx cerebri located?
From front to back of brain
between the right and left hemispheres
What is the falx cerebri attached to anteriorly?
Crista galli
What is the falx cerebri attached to posteriorly?
Upper part of tentorium cerebelli
Where is the tentorium cerebelli located?
Beneath the right and left hemispheres of the brain
above the cerebellum
Is the tentorium cerebelli continuous?
No
has a gap in the middle of it
What is the purpose of the gap in the middle of the tentorium cerebelli?
Allows the brainstem to pass through it
between the hemispheres of the brain and the spinal cord
What do dural venous sinuses contain?
Venous blood
What are the dural venous sinuses in the falx cerebri?
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
What does the straight sinus do?
Joins together the superior and inferior sagittal sinuses
Where do the superior sagittal sinus and straight sinus converge?
The confluence of sinuses
What are the dural venous sinuses of the tentorium cerebelli?
The transverse sinuses x2
What dural venous sinus arises from the confluence of sinuses?
The transverse sinuses x2
How do the transverse sinuses travel?
Laterally
What are the continuations of the transverse sinuses x2?
The sigmoid sinuses
What do the sigmoid sinuses continue as?
Part of the internal jugular vein
Where are the cavernous sinuses located?
Either side of sella turcica
What does the cavernous sinus drain into?
The superior and inferior petrosal sinuses
What are dural venous sinuses?
Space between the dural folds of the meningeal layer and periosteal layer of the dura
What does the superior petrosal sinus drain into?
Transverse sinus
What does the inferior petrosal sinus continue as?
Part of internal jugular vein
What can a fracture of the crista galli result in?
Tearing of falx cerebri
damage to superior and inferior sagittal sinuses
leakage of CSF, leakage of blood
What does the arachnoid layer look like?
Translucent
How closely does the arachnoid surround the brain?
Doesn’t follow every sulci of brain
What does the sub-arachnoid space contain?
CSF
Cerebral arteries, veins
What do the cerebral veins drain into?
Dural venous sinuses
How do the cerebral veins in the subarachnoid space drain into the dural venous spaces in the dura?
Bridging veins cross the subarachnoid space, arachnoid, subdural space and meningeal dura
connect together the cerebral veins and the dural venous sinuses
What do the dural venous sinuses drain into?
Internal jugular vein
What effect does increased intracranial pressure have on the brain?
Herniation
What can cause an increase in intracranial pressure?
Intracranial haemorrhage
Tumours
What effect does brain herniation have on the brain itself?
Brain gets compressed
How closely does the pia surround the brain?
Follows every sulci of the brain
Where does the superior petrosal sinus run in the cranial cavity?
Superior petrosal sinus runs above the ridge of the petrous bone
How are the cavernous sinuses on each side of the head related to each other?
Intercavernous sinus connects them together
What is located between the two cavernous sinuses on each side?
Pituitary gland
Where does the inferior petrosal sinus run in the cranial cavity?
Below the ridge of the petrus bone
How can the brain herniate?
Pushed against dural folds
Pushed through foramen magnum
