Cerebral Vasculature And Meninges

Question 1

Leptomeninx

Answer 1

Arachnoid and pia matter combined

Question 2

Meninges functions

Answer 2

Protect the brain

Form supporting framework for vasculature

Encloses fluid-filled cavity

Question 3

Dura mater

Answer 3

Tough thick external fibrous layer composed of 2 layers:

External periosteum layer: formed by periosteum covering the internal surface of the calvaria
highly vascular and innervated

Internal meningeal layer: fused with periosteum layer and is avasculature

Question 4

Dura septa

Answer 4

Formed by separation of rural layers

Divide the cranial cavity into compartments and partial partitions between certain parts of brain

Functions to reduce or prevent displacement of the brain when head moves

Question 5

Tentorium cerebellum

Answer 5

Wide septum held by the falx celebri and appears tent like

• separates the occipital lobes from cerebellum

Contains a tentorial notch for the brain stem

Question 6

Falx cerebri

Answer 6

Vertical midline dura unfolding that partially separates the cerebellum hemispheres

Question 7

Diaphragma sellae

Answer 7

Circular sheet of dura over the sella turcica that covers the pituitary gland and passageway for infundibulum and hypophysial veins

Question 8

Blood supply to the dura mater

Answer 8

Anterior dura = anterior meningeal artery

Posterior dura = Supplied by branches of vertebral and occipital Arteries

Lateral dura = supplied by middle meningeal artery

Question 9

Potential pathological spaces for dura mater

Answer 9

Dura-cranial interface: pathologically generated space between the dura mater and the calvaria
(Epidural hemorrhage)

Dura-arachnoid interface:
Pathologically generated space between the dura and arachnoid maters
(Subdural hemorrhage)

Question 10

Subarachnoid space

Answer 10

Non-pathological potential space that is between the arachnoid and Pia mater
- contains CSF, arteries, veins and trabeculae

enlarged areas of the subarachnoid space are called subarachnoid cisterns

Question 11

Subarachnoid hemorrhage

Answer 11

Trauma or intracranial aneurysm causes extravastion of blood into the subarachnoid space

• portion where CSF is also present

Question 12

Dura venous sinuses purpose

Answer 12

Purpose is to collect blood from superficial and deep veins of the brain as well as recycle CSF
- empties contents into internal jugular vein

Question 13

Falx cerebelli

Answer 13

Small fold in the midline of the dura in the posterior cranial fossa and separates the left and right cerebellar hemispheres

Question 14

Sensory innervation to the periosteal layer of the dura

Answer 14

Anterior, middle cranial fossa dura and falx cerebri/tentorium cerebelli = V1-3

Posterior cranial fossa dura = C2-3

Question 15

What sinuses drain into the confluence of sinuses

Answer 15

Superior sagittal

Inferior sagittal and straight

Occipital

(All four are single sinuses)

Question 16

What sinus does the confluence of sinuses drain into?

Answer 16

Transverse sinuses (paired)

Question 17

Where do the transverse and sigmoid sinus drain into?

Answer 17

The internal jugular foramen in the jugular foremen

Question 18

Cavernous sinuses

Answer 18

Paired sinuses Located in the middle cranial fossa just lateral to each side of the sella turcica
receives venous blood from
-orbit
-pituitary gland
-superficial veins of cerebral hemisphere
-small dural sinuses (sphenoparietal sinuses)

• cranial nerves 3,4,V1-2,6 all run through this sinus as well as the internal carotid artery*

Question 19

What sinuses drain into the cavernous sinus?

Answer 19

Superior sinuses

Intercavernous sinuses

Sphenoparietal sinuses

Question 20

What is special about the Inferior petrosal sinus?

Answer 20

It is the only sinus near the cavernous sinus that does not drain into it
- drains directly into the internal jugular vein

Question 21

Parts of vertebral artery (4)

Answer 21

Prevertebral part: subclavian artery -> transverse foramen of C6

Cervical part: transverse foramina of C6- > C1

Atlantic part: transverse foramina of C1 -> around lateral atlas masses and into the posterior Atlanta-occipital membrane -> vertebral canal
only part visible through suboccipital triangle

Intracranial part: vertebral canal -> dura and arachnoid mater -> foramen magnum via posterior cranial fossa -> ascend brainstem and form fused basilar artery at medullopontine sulcus

Question 22

Medullopontine sulcus

Answer 22

Site where right and left vertebral arteries fuse together to form one basilar artery

Question 23

Branches of vertebral and basilar artery

Answer 23

Anterior and posterior spinal arteries (vertebral)
- supply spinal cord

Posterior/ anterior inferior cerebellar (PICA/AICA) and superior cerebellar arteries

• AICA = basilar
• PICA = vertebral
• supply the cerebellum

Posterior cerebral arteries (Basilar)
- supply entire occipital lobes, inferior parts of temporal lobes, and posterior parts of parietal lobes

Question 24

Internal carotid artery parts (4)

Answer 24

1st part: (cervical) = Common carotid artery -> base of skull

2nd part: (petrous) = base of skull -> through carotid canal

3rd part: (cavernous) = exit of carotid canal -> periosteal dura -> through cavernous sinus

4th part: (cerebral) = exit of cavernous sinus -> bifurcation of anterior and middle cerebral arteries

Question 25

Branches of the internal carotid arteries

Answer 25

Ophthalmic artery: eye

Posterior communicating artery: from internal carotid -> proximal part of posterior cerebral artery
- is an active anastomosis

Anterior choroidal artery: deep brain

Anterior cerebral artery: Medial surface of anterior cerebral hemisphere
- supplies medial parts of frontal and parietal lobes

Middle cerebral artery: lateral sulcus of cerebral hemisphere
- supplies superior surface of temporal lobe, lateral portion of frontal lobe

Question 26

Cerebral arterial circle of Willis

Answer 26

Pentagon shaped circle of vessels on midbrains ventral surface

Encircles optic chiasma, infundibulum and maxillary bodies

Includes carotid and vertebro-basilar arteries

Acts as a potential vascular shunt to provide collateral circulation to the cerebral hemispheres if a proximal vessel is occluded
* most common examples are if ICA or vertebral-basilar system are blocked*

Question 27

Branches of the cerebral arterial circle of Willis

Answer 27

• from anterior -> posterior*

Anterior communicating artery (single artery)
- allows communication between left and right anterior cerebral arteries

Anterior cerebral arteries (paired arteries)
- w/ anterior communicating artery, allows communication between both right and left internal carotid arteries

Internal carotid arteries (paired arteries)

Posterior communicating arteries (paired arteries)
- communication between internal carotid and posterior cerebral arteries

Posterior cerebral arteries (paired arteries)
- w/ posterior communicating, allows communication between basilar artery and internal carotid arteries

Question 28

Vertebro-basilar circulation

Answer 28

Includes vertebral arteries and basilar arteries (and branches)

Supplies blood to the medulla, pons, mesencephalon and cerebellum

Question 29

Watershed areas

Answer 29

Areas of brain where blood supply is provided by distal regions of 2 or more arteries (allows easy anastomosis and multiple blood supply to one area)

Watershed areas in the brain:

• ACA and MCA (frontal lobe)
• MCA and PCA (anterior occipital/ posterior parietal lobe)

Pros: if one artery dies/infarcts, the other can provide adequate blood supply to the area

Cons: if a global reduction in blood volume/flow (multiple arteries are obstructed) then these areas die first usually