Meninges & Venous Sinuses Flashcards
What does the falx cerebri enclose?
The superior sagittal sinus in its upper attached border and the inferior sagittal sinus in its lower free border
Where is the falx cerebri located?
Between the 2 cerebellar hemispheres
Where does the falx cerebri run from?
The internal occipital protuberance to the foramen magnum
What forms the Superior Sagittal Sinus? What does it occupy?
From several cerebral veins which drain the brain
Occupies the attached base of the falx cerebri
State the location of the Superior Sagittal Sinus
Anterior to crista galli and ends posteriorly at the confluence of veins
What are arachnoid granulations?
Small extensions of arachnoid matter that project through the dura mater into the superior sagittal sinus
What is the role of arachnoid granulations?
Allow CSF to leak through from the superior sagittal sinus to the superior sagittal sinus
Describe the route of the inferior sagittal sinus
Starts anteriorly in the region of crista galli and follows the inferior border of falx cerebri.
As it approaches the tentorium cerebelli, joins with the great cerebral vein to form the straight sinus.
Where does the Inferior Sagittal Sinus receive blood from?
From small cerebral veins
What forms the straight sinus?
Joining of the inferior sagittal sinus & great cerebral vein
Describe the route of the straight sinus
Internal occipital protuberance where it ends at the confluence of veins which leads to the left transverse sinus
Where is the straight sinus found?
At the interval between the base of falx cerebri and tentorium cerebelli
What passes through the jugular foramen?
Cranial Nerves 9,10, 11
Sigmoid sinus & Inferior petrosal sinus
Where does the cavernous sinus receive blood from?
Superior and inferior opthalmic veins of the orbit, cerebral veins and the sphenoparietal sinus
Where does the sphenoparietal sinus run ?
Under the lesser wing of sphenoid
How is the cavernous sinus drained?
By the Superior and inferior petrosal sinuses on both sides
Where does the cavernous sinus lie?
On the side of the side of the sella turcica
Where does the abducent nerve lie?
Posterolateral to internal carotid artery
Where do most of the nerves in the cavernous sinus lie?
In the lateral wall
What causes a subdural hemorrhage?
Rupture of cerebral veins as they enter the superior sagittal sinus & creates pressure on the brain
Where is the basilar sinus located?
Below the dura of the clivus
Where does the basilar sinus receive blood from?
The cavernous sinus and inferior petrosal sinus
Where does the basilar sinus drain to?
Drains to the vertebral plexus of veins through the foramen magnum
Describe the route of the occipital sinus
Travels within the base of falx cerebelli down along the internal occipital crest. It passes along the foramen magnum and communicates with the vertebral plexus of veins
What drains the cavernous sinus?
Superior & Inferior Petrosal sinuses
What does the Superior petrosal sinus travel within?
The superior petrosal sulcus
What does the Superior petrosal sinus empty into?
Sigmoid sinus
What does the Inferior petrosal sinus empty into?
Internal Jugular Vein
What does the Inferior petrosal sinus travel within?
The inferior petrosal sulcus
Describe the route of the transverse sinus
The attached base of tentorium cerebelli from the confluence. As it approaches the petrous temporal ridge, it takes a deeper S-shaped course medially as the sigmoid sinus
Is the Transverse sinus paired or single?
Paired
Is the sigmoid sinus paired or single?
Paired
Describe the route of the sigmoid sinus
Continues medially from the transverse sinus at the base of the petrous ridge & ends at the mouth of jugular foramen.
Where does all the blood from the venous sinuses drain through?
Jugular foramina to the internal jugular vein
What can infections in the dangerous area of the face lead to?
Cavernous sinus through ophthalmic vein and cause cavernous sinus thrombosis (clot)
Where is the dangerous area of the face?
Mainly covers upper lip, nose & medial angle of eye
What can result with as a complication with a boil to the face?
Cavernous Sinus Thrombosis
What are the consequences of a Cavernous Sinus Thrombosis?
Fever, ptosis (drooping eye/ not able to open fully), proptosis (protrusion/buldging of eye) and ophthalmoplegia (paralysis of extraocular muscles due to dysfunction of cranial nerves III, IV, and VI)
How is a Cavernous Sinus Thrombosis formed?
Boil drains through facial vein, via ophthalmic vein through cavernous sinus. Blood clot forms in the cavernous sinuses to try to prevent bacteria spreading, then results in Cavernous Sinus Thrombosis.
