L4 - blood supply to the brain

Question 1

what % of o2 consumption does the brain use

Answer 1

20

Question 2

what happens with an increase in intracranial pressure

Answer 2

• herniations or certain structures into other places

- compression of ventricles

Question 3

TIA

Answer 3

transient ischaemic attack

Question 4

main arteries which supply the brain

Answer 4

• vertebral

- internal carotid

Question 5

what is the vertebral artery a branch of

Answer 5

subclavian

Question 6

how does the vertebral artery travel from neck to brain

Answer 6

• Ascend in the neck through transverse foramen of the cervical vertebrae
• Enter skull via foramen magnum
• fuse at base of brainstem to form basilar artery

Question 7

basilar artery - how it forms

Answer 7

fusion of vertebral arteries at base of brainstem

Question 8

what is the internal carotid artery a branch of

Answer 8

common carotid

Question 9

where does the common carotid artery give off the internal and external carotid artery

Answer 9

neck

Question 10

how many branches does the external artery supply to the face

Answer 10

8

Question 11

how does the internal carotid artery enter the skull

Answer 11

carotid canals in temporal bone

Question 12

where does the internal carotid artery emerge

Answer 12

other side of optic chiasm

Question 13

where are the characteristic bands of the internal carotid artery

Answer 13

cavernous sinus

Question 14

how many pairs of cerebellar arteries does the vertebral artery give off

Answer 14

3

Question 15

what are the pairs of arteries which the vertebral artery gives off

Answer 15

• posterior inferior cerebellar artery (PICA)
• superior cerebellar artery (SCA)
• posterior cerebral artery (PCA)

Question 16

which arteries does the vertebral artery give off

Answer 16

• posterior inferior cerebellar artery
• anterior spinal artery
• posterior spinal artery
• anterior inferior cerebellar artery
• basilar artery
• superior cerebellar artery
• posterior cerebral artery

Question 17

how many branches of the vertebral artery are there

Answer 17

7

Question 18

posterior inferior cerebellar artery (PICA)

Answer 18

supplies the posterior and inferior surface of the cerebellum

Question 19

anterior spinal artery

Answer 19

anterior aspect of spinal cord

Question 20

posterior spinal artery

Answer 20

• posterior aspect of spinal cord

- In some people they come from the VA and in some people, they come from the PICA

Question 21

anterior inferior cerebellar artery

Answer 21

supplies anterior and inferior portions of the cerebellum

Question 22

basilar artery

Answer 22

Tiny branches in the surface of the pons of the brainstem: transverse pontine branches – supply the anterior aspect of the pons

Question 23

superior cerebellar artery

Answer 23

tucks under and supplies the superior aspect of the cerebellum

Question 24

posterior cerebral artery

Answer 24

• terminal branch of the basilar artery

- supplies posterior aspect of the cerebrum

Question 25

terminal branch of the basilar artery

Answer 25

posterior cerebral artery

Question 26

branches of the internal carotid artery

Answer 26

middle cerebral artery | anterior cerebral artery

Question 27

paired branches of the internal carotid artery

Answer 27

middle cerebral artery

Question 28

middle cerebral artery

Answer 28

Supply the middle and lateral portions of the cerebrum

Question 29

anterior cerebral artery

Answer 29

Tucks under the midline portion of each hemisphere to supply its anterior and medial aspect

Question 30

circle of willis

Answer 30

Anastomotic loop interconnecting the internal carotid and vertebral / basilar system

Question 31

function of circle of willis

Answer 31

ensures collateral circulation if decreased blood flow if one vessel is occluded

Question 32

location of circle of willis

Answer 32

surrounds optic chiasma and hypothalamus

Question 33

constituents of the circle of willis

Answer 33

- anterior, middle , posterior cerebral arteries - anterior and posterior communicating arteries - internal carotid arteries - basilar artery

Question 34

examples of variations within the circle of willis

Answer 34

- Absence of anterior communicating artery - Both anterior cerebral arteries come from the same internal carotid artery (1 common trunk) - Under-developed / not present posterior communicating artery - Under-developed / not present posterior communicating artery x2 - Under-developed PCA x1 - Under-developed PCA x2

Question 35

when does a berry aneurysm occur

Answer 35

weakening of the wall, especially when the arteries are highly branched

Question 36

what % of strokes are caused by a berry aneurysm

Answer 36

10%

Question 37

what does the ACA supply

Answer 37

superior and medial area of the frontal and parietal lobes and the corpus callosum

Question 38

what does the MCA supply

Answer 38

lateral areas of the frontal, temporal and parietal

Question 39

what does the PCA supply

Answer 39

occipital lobe and inferior and medial surface of the temporal lobe

Question 40

striate arteries

Answer 40

deep / perforating arteries

Question 41

functions of striate arteries

Answer 41

- grey matter - thalamus - deep white matter - internal capsule - supply includes descending motor pathway

Question 42

internal capsule

Answer 42

major fibre bundle to and from cerebral cortex and aids motor functions

Question 43

watershed areas

Answer 43

regions which receive blood supply from distal areas of adjacent cerebral arteries

Question 44

what happens to watershed areas when there is a drop in pressure

Answer 44

neither of the distal branches reach the areas which can result in a susceptible ischaemia

Question 45

where do superficial veins drain into

Answer 45

straight into the dural sinuses

Question 46

where do deep veins drain into

Answer 46

great cerebral vein --> straight sinus --> confluence of sinuses

Question 47

cavernous sinus

Answer 47

located lateral to the body of the sphenoid bone

Question 48

confluence of sinuses

Answer 48

where the superior sagittal, straight and transverse sinuses meet

Question 49

where does venous blood drain into from the confluence of sinuses

Answer 49

internal jugular veins

Question 50

clinical relevance of cavernous sinus anatomy

Answer 50

Infections are likely to reach the cavernous sinus if there is injury to the ‘danger triangle’ of the face

Question 51

what is the danger triangle

Answer 51

here, veins which have direct communication to the cavernous sinus

Question 52

examples of infections which can spread into the cranial cavity from the cavernous sinus

Answer 52

- meningitis | - cavernous sinus thrombosis

Question 53

clinical features of cavernous sinus thrombosis

Answer 53

- headaches - oedema of the eyeball - numbness of the face - palsies of cranial nerves

Question 54

location of meningeal artery

Answer 54

periostial dura

Question 55

bridging veins

Answer 55

the way in which the superficial cerebral arteries empty into the superior sinus

Question 56

how to the bridging veins enter the superior sagittal sinus

Answer 56

pierce the arachnoid before piercing the superior sagittal sinus

Question 57

where are the cerebral arteries and veins

Answer 57

subarachnoid space

Question 58

epidural / extradural haemorrhage

Answer 58

torn meningeal artery

Question 59

subdural haemorrhage

Answer 59

torn bridging veins

Question 60

subarachnoid haemorrhage

Answer 60

torn cerebral arteries

Question 61

location of superior sagittal sinus

Answer 61

along the edge of the falx cerebri

Question 62

cerebrovascular accident = CVA

Answer 62

a stroke

Question 63

when does a CVA occur

Answer 63

when the blood vessel is occluded and the brain becomes infracted

Question 64

communicating arteries

Answer 64

little blood - the blood will flow from one direction to another if there is blockage in the system using these communicating vessels