Meninges And Venous Sinuses Check All Flashcards
What are the three membranes that surround the brain and spinal cord?
Dura mater, arachnoid mater, pia mater
What are the two layers of the dura mater in the brain?
Endosteal layer, meningeal layer
What is the endosteal layer of the dura mater?
The ordinary periosteum covering the inner surface of the skull bones
Does the endosteal layer extend through the foramen magnum?
No, it does not extend through the foramen magnum - becomes continuous with periosteum on outside of skull bones at foramina
What does the meningeal layer of the dura mater cover? What happens to it at the foramen magnum?
It covers the brain.
Becomes continuous with dura mater of spinal cord at foramen magnum
What happens to the meningeal layer of the data mater at the foramina of the skull?
It provides tubular sheaths for the cranial nerves, these then fuse with epineuium of nerves
What are the four septa sent inward by the meningeal layer?
Falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae
What is the function of the septa in the cranial cavity?
To restrict rotatory displacement of the brain
Where is the falx cerebri located?
What is it attached to anteriorly and posteriorly?
In the midline between the two cerebral hemispheres
Anteriorly = frontal crest and crista galli
Posteriorly = blends in midline with upper part of tentorium cerebelli
What runs along the upper fixed margin and the feee inferior margin of the falx cerebri?
upper margin = Superior sagittal sinus
inferior margin = inferior sagittal sinus
What is the tentorium cerebelli?
A crescent-shaped fold of dura mater that roofs over the posterior cranial fossa (overs cerebellum and supports occipital lobes)
What is the tentorial notch?
A gap in the anterior part of the tentorium cerebelli for the passage of the midbrain
What structures are attached to the fixed border of the tentorium cerebelli?
- Posterior clinoid processes
- Superior borders of the petrous bones
- Grooves for the transverse sinuses on the occipital bone
Does the anterior free border of the tentorium cerebelli attach to anything?
Yes, crosses attached border and is affixed to anterior clinoid process on each side
What passes forward at the point where the free and attached borders of the tentorium cerebelli cross?
The third and fourth cranial nerves to enter lateral wall of cavernous sinus
What is found close to the apex of the petrous part of the temporal bone?
A recess for the trigeminal nerve and the trigeminal ganglion
Which sinus runs along the attachment of the falx cerebri to the tentorium cerebelli?
Straight sinus
Describe the location of three sinuses that are in contact with the tentorium cerebelli
- straight sinus along attachment to falx cerebri
- superior petrosal sinus along attachment to petrous bone
- transverse sinus along attachment to occipital bone
Fill in the blank: The _____ mater is the outermost layer of the meninges.
Dura
True or False: The pia mater is the strongest layer of the meninges.
False
What is the falx cerebelli attached to? Which parts of the brain does it separate?
internal occipital crest
Projects forwards between two cerebellar hemispheres
What shape is the falx cerebelli?
Sickle-shaped
It is a small fold of dura mater.
What is the function of the diaphragma sellae?
Forms the roof for the sella turcica
It has a small opening that allows passage of the stalk of the hypophysis cerebri.
What is the shape of the diaphragma sellae?
A small, circular fold of dura mater
It is located above the sella turcica and has an opening for the hypophysis cerebri to pass through
Label this diagram starting at top right and working anticlockwise (Use paper and pen!)
1) Superior sagittal sinus
2) straight sinus
3) great cerebral vein of gallen
4) tentorium cerebelli
5) superior sagittal sinus
6) falx cerebri
7) inferior sagittal sinus
8) sphenoparietal sinus
9) intercavernous sinus
10) superior petrosal sinus
11) basilar venous plexus
12) inferior petrosal
13) jugular foramen
14) sigmoid sinus
15) transverse sinus
16) occipital sinus
17) falx cerebelli
18) confluence of sinuses
Fill in the blank: The _______ contains the occipital sinus.
posterior fixed margin of the falx cerebelli
True or False: The falx cerebelli is larger than the falx cerebri.
False
The falx cerebelli is smaller and located in the cerebellum.
What nerves provide the dura mater with sensory supply?
Branches of the trigeminal, vagus, first three cervical nerves, and sympathetic system
These branches facilitate the sensory innervation of the dura mater.
What sensation does stretching of the dura produce?
Headache
The dura is sensitive to stretching, which triggers headache sensations.
What nerve stimulation causes referred pain to the same side of the head?
Stimulation of the sensory endings of the trigeminal nerve above the tentorium cerebelli
This phenomenon is due to the sensory pathways of the trigeminal nerve.
What is the effect of stimulating dural endings below the level of the tentorium?
Referred pain to the back of the neck and scalp
This referred pain follows the distribution of the greater occipital nerve.
From which arteries does the dura mater receive its arterial supply?
Internal carotid, maxillary, ascending pharyngeal, occipital, vertebral arteries, middle meningeal
These arteries ensure the vascularization of the dura mater.
Which artery is most clinically significant for the dura mater?
Middle meningeal artery
It is commonly damaged in head injuries.
Where does the middle meningeal artery arise from?
Maxillary artery in the infratemporal fossa
This artery plays a crucial role in supplying the dura mater.
How does the middle meningeal artery enter the cranial cavity?
Through the foramen spinosum
It lies between the meningeal and endosteal layers of dura after entering.
What does the anterior (frontal) branch of the middle meningeal artery groove?
Anteroinferior angle of the parietal bone
Its course corresponds to the underlying precentral gyrus of the brain.
What is the function of the meningeal veins?
Drain blood from the dura mater
Where does the middle meningeal vein drain to?
The middle meningeal vein drains into the pterygoid venous plexus or the sphenoparietal sinus.
Fill in the blank: The middle meningeal vein follows the branches of the _______.
middle meningeal artery
This relationship is crucial for venous drainage of the dura mater.
What is the arachnoid mater?
A delicate, impermeable membrane covering the brain, lying between the pia mater and the dura mater
The arachnoid mater is one of the three meninges surrounding the brain.
What separates the arachnoid mater from the dura mater?
The subdural space
The subdural space is a potential space that can become significant in certain medical conditions.
What fills the subarachnoid space?
Cerebrospinal fluid
Cerebrospinal fluid serves to cushion the brain and maintain intracranial pressure + to remove waste products of neuronal activity
subarachnoid space = space between arachnoid and Pia mater
What are subarachnoid cisternae?
Widely separated areas between the arachnoid and pia mater due to arachnoid running over sulci in brain, whereas pia remains close to brain
These cisternae allow for the accumulation of cerebrospinal fluid.
Name the three subarachnoid cisterns and where they are found.
- Cisterna cerebellomedullaris = between inferior surface of cerebellum and roof of 4th ventricle
- cisterna pontis = anterior surface of pons and medulla oblongata
- cisterna interpeduncularis = between two cerebral peduncles
All in free communication with eachother and remainder of subarachnoid space
What are arachnoid villi?
Projections of the arachnoid into venous sinuses
Arachnoid villi facilitate the drainage of cerebrospinal fluid into the bloodstream.
Where are arachnoid villi most numerous?
Along the superior sagittal sinus
This area is critical for the absorption of cerebrospinal fluid.
What do aggregations of arachnoid villi form?
Arachnoid granulations
Arachnoid granulations play a role in the resorption of cerebrospinal fluid.
What connects the arachnoid to the pia mater?
Delicate strands of fibrous tissue
These strands traverse the fluid-filled subarachnoid space.
What must pass through the subarachnoid space?
Structures passing to and from the brain to the skull or its foramina
This includes all cerebral arteries, veins, and cranial nerves.
What happens at the point where cranial nerves exit the skull?
The arachnoid fuses with the epineurium of the nerves
This fusion helps protect and support the nerves as they exit the cranial cavity.
How does the arachnoid relate to the optic nerve?
It forms a sheath that extends into the orbital cavity through the optic canal
This sheath fuses with the sclera of the eyeball.
Fill in the blank: The subarachnoid space extends around the optic nerve as far as the _______.
eyeball
This extension provides a protective layer for the optic nerve.
What does the pia mater form in the brain’s ventricles?
The tela choroidea of the roof of the brain’s third and fourth ventricles
The tela choroidea is a thin membrane that supports the choroid plexus.
Describe the production and flow of CSF.
- Choroid plexuses in lateral, thirs and fourth ventricles produce CSF.
- Escapes from ventricular system of brain through one of three holes in fourth ventricle and enters subarachnoid space.
- circulates upwards over surfaces of cerebral hemispheres and downwards around spinal cord
- Spinal subarachnoid space extends to second sacral vertebra
- fluid enters bloodtream by passing into arachnoid villi and diffusing through their walls
Which vertebra does the subarachnoid space extend to?
Second sacral vertebra
What is the pia mater?
A vasular membrane that closely invests the brain. Covers gyri and descends into sulci. Fuses with epineurium of nerves.
Cerebral arteries entering brain carry sheath of pia mater with them
With which structure does the pia mater fuse to form the choroid plexuses?
The ependyma
The choroid plexuses are involved in the production of cerebrospinal fluid.
In which ventricles are the choroid plexuses formed?
Lateral, third, and fourth ventricles
The choroid plexus is crucial for maintaining the homeostasis of cerebrospinal fluid.
Where are the venous sinuses of the cranial cavity located?
Between the layers of the dura mater
What type of tissue lines the venous sinuses?
Endothelium
What is absent in the walls of the venous sinuses?
Muscular tissue
no muscular layer, no valves
Do venous sinuses contain valves?
No
No muscular layer, no valves
What do venous sinuses receive tributaries from?
- Various parts of the brain
- The diploe
- The orbit
- The internal ear
Where does the superior sagittal sinus begin?
At the foramen cecum
What does the superior sagittal sinus occasionally receive at the foramen cecum?
A vein from the nasal cavity
What does the superior sagittal sinus groove?
The vault of the skull
At which anatomical feature does the superior sagittal sinus deviate to one side?
The internal occipital protuberance
Normally deviates to the right to become transverse sinus. Superior sagittal sinus communicates with 2-3 irregularly shapes lacunae on each side via small openings. Numerous arachnoid villi and granulations project into lacunae, which receive diploic and meningeal veins
True or False: The walls of venous sinuses have muscular tissue.
False
What does the superior sagittal sinus receive during its course?
The superior cerebral veins
It is dilated at the internal occipital protuberance to form the confluence of the sinuses.
What is the confluence of the sinuses?
A dilation at the internal occipital protuberance where the superior sagittal sinus connects with the right transverse sinus
It also connects to the opposite transverse sinus and receives the occipital sinus.
Where does the inferior sagittal sinus occupy?
The free lower margin of the falx cerebri.
What does the inferior sagittal sinus join to form the straight sinus?
What other veins join the inferior sagittal sinus?
The great cerebral vein at the free margin of the tentorium cerebelli.
Cerebral veins from medial surface of cerebral hemispheres also join inferior sagittal sinus
What is formed by the union of the inferior sagittal sinus and the great cerebral vein?
The straight sinus.
What do the transverse sinuses receive?
- Superior petrosal sinuses
- Inferior cerebral veins
- Cerebellar veins
- Diploic veins
Where do the transverse sinuses begin? What is each transverse sinus continuous with proximally?
At the internal occipital protuberance.
- right transverse sinus usually continuous with sperior sagittal sinue
- left transverse sinus usually continuous with the straight sinus
What is the continuation of the transverse sinuses?
The sigmoid sinuses.
each turns downwarda and medially and grooves the mastoid part of the temporal bone to lie behind mastoid antrum. Then turn forward and donwward through posterior part of jugular foamen to become continuous with superior bulb of internal jugular vein
What do the sigmoid sinuses become continuous with?
The superior bulb of the internal jugular vein.
Where does the occipital sinus commence?
Near the foramen magnum.
= small sinus occupying the attached margin of the falx cerebelli. Commences near the foramen magnum where it communicates with the vertebral veins and drains into the confluence of the sinuses
What does the occipital sinus communicate with?
The vertebral veins.
Where are the cavernous sinuses located?
Which boney landmarks does it extend between?
- In the middle cranial fossa on each side of the body of the sphenoid bone.
- Extends from superior orbital fissure to apex of petrous part of temporal bone
What anatomical feature gives the cavernous sinuses a spongy appearance?
Numerous trabeculae crossing their interior.
What runs through the cavernous sinus?
- Internal carotid artery (surrounded by sympathetic plexus)
- Abducent nerve
What lies between the endothelial lining and the dura mater in the cavernous sinus?
The third and fourth cranial nerves + V1 and V2 (the ophthalmic and maxillary divisions of the trigeminal nerve.)
What drains posteriorly from the cavernous sinus?
The superior and inferior petrosal sinuses.
What is the function of the superior and inferior petrosal sinuses?
- Superior petrosal sinus drains into the transverse sinus
- Inferior petrosal sinus drains into the internal jugular vein
Fill in the blank: The two cavernous sinuses communicate with each other by means of the _______.
anterior and posterior intercavernous sinuses. (these run inis diaphragm sellae in front and behind stalk of hypophysis cerebri)
What is an important communication of each cavernous sinus?
With the facial vein through the superior ophthalmic vein.
What does the superior sagittal sinus receive during its course?
The superior cerebral veins
It is dilated at the internal occipital protuberance to form the confluence of the sinuses.
What is the confluence of the sinuses?
A dilation at the internal occipital protuberance where the superior sagittal sinus connects with the right transverse sinus
It also connects to the opposite transverse sinus and receives the occipital sinus.
Where does the inferior sagittal sinus occupy?
The free lower margin of the falx cerebri.
What does the inferior sagittal sinus join to form the straight sinus?
The great cerebral vein at the free margin of the tentorium cerebelli.
What is formed by the union of the inferior sagittal sinus and the great cerebral vein?
The straight sinus.
What do the transverse sinuses receive?
- Superior petrosal sinuses
- Inferior cerebral and cerebellar veins
- Diploic veins
Where do the transverse sinuses begin?
At the internal occipital protuberance.
What is the continuation of the transverse sinuses?
The sigmoid sinuses.
What do the sigmoid sinuses become continuous with?
The superior bulb of the internal jugular vein.
Where does the occipital sinus commence?
Near the foramen magnum.
What does the occipital sinus communicate with?
The vertebral veins.
Where are the cavernous sinuses located?
In the middle cranial fossa on each side of the body of the sphenoid bone.
What anatomical feature gives the cavernous sinuses a spongy appearance?
Numerous trabeculae crossing their interior.
What runs through the cavernous sinus?
- Internal carotid artery
- Abducent nerve
What lies between the endothelial lining and the dura mater in the cavernous sinus?
The third and fourth cranial nerves, and the ophthalmic and maxillary divisions of the trigeminal nerve.
What drains posteriorly from the cavernous sinus?
The superior and inferior petrosal sinuses.
What is the function of the superior and inferior petrosal sinuses?
- Superior petrosal sinus drains into the transverse sinus
- Inferior petrosal sinus drains into the internal jugular vein
Fill in the blank: The two cavernous sinuses communicate with each other by means of the _______.
anterior and posterior intercavernous sinuses.
What is an important communication of each cavernous sinus?
With the facial vein through the superior ophthalmic vein.
Where are the superior and inferior petrous sinuses located?
Small sinuses on superior and inferior borders of petrous part of temporal bone on each side
What does the superior petrous sinus drain?
the cavernous sinus into the transverse sinus
What does the inferior petrous sinus drain?
cavernous sinus into internal jugular vein
