Cerebral vasculature

Question 1

why is the brain v vulnerable if blood supply is impaired?

Answer 1

Although brain makes up 2% of total body weight it uses:
10-20% cardiac output,
20% body O2 consumption , 66% liver glucose
if these requirements aren’t met braincells may infarct

Question 2

What structures supply blood to the brain and where do they come from

Answer 2

1) Vertebral artery ( right comes from R subclavian artery –> branch of the brachiocephalic artery . L from left subclavian artery.
2) Internal carotid arteries which split into common carotid at laryngeal prominence ( R comes from r common carotid –> branch of the brachiocephalic artery. L from left common carotid )

Question 3

What are the 3 branches of the aorta

Answer 3

Brachiocephalic artery
left subclavian
left common carotid

Question 4

What are the branches of the brachiocephalic artery

Answer 4

R common carotid ( giving internal + external carotid) + R subclavian ( giving vertebral artery

Question 5

Which foramen does the vertebral artery pass through

Answer 5

transverse foramen on vertebral body

Question 6

Where does the internal and external carotid artery bifurcate from the common carotid artery

Answer 6

level of laryngeal prominence

Question 7

What is the circle of willis

Answer 7

Circle of blood vessels in the brain

Question 8

What are the 2 main arteries that feed the circle of willis

Answer 8

internal carotid + vertebral

Question 9

Describe the circle of willis

Answer 9

See image on docs

Question 10

Where does the basilar artery sit

Answer 10

on the base of the pons

Question 11

What does the middle , anterior and posterior cerebral artery supply

Answer 11

middle –> temporal + parietal lobes

anterior –> frontal +superior medial parietal lobes)

Posterior –> occipital + inferior temporal lobes

Question 12

Why is the circle of willis beneficial

Answer 12

can avoid blockage in any major artery ( ie internal carotid) due to compensatory flow form the other side
though not universal as communicating arteries are thin

Question 13

How are sinuses created

Answer 13

Due to separation of periosteal and meningeal layers of the dura

Question 14

What does the superior , straight and occipital sinus drain into

Answer 14

Confluence of sinuses

Question 15

What does the confluence of sinus drain into

Answer 15

Transverse sinus then to sigmoid sinus

Question 16

What does the signmoid sinus drain into

Answer 16

Internal jugular vein

Question 17

What is the order of venous drainage in the brain

Answer 17

1) sagittal sinus
2) Confluence of sinuses
3) Transverse sinus
4) sigmoid sinus
5) IJV ( internal jugular)

Question 18

name the 3 layers of meninges in the brain

Answer 18

Dura ( periosteal , meningeal. Infoldings form falx cerebri + falx cerebelli

arachnoid mater : Subarachnoid space has CSF –> collapses onto brain if CSF not there

pia mater

Question 19

What are the 4 types of haemorrhage

Answer 19

Extradural
subdrual
subarachnoid
intracerebral

Question 20

What causes extradural bleeds

Answer 20

Trauma often to the pterion region damaging middle meningeal artery

Question 21

Why are extradural haemorrhage so dangerous

Answer 21

As arterial high pressure bleed. can increase intercranial pressure ( stripping periosteal layer away from bone) and compress brainstem
Will have immediate clinical effects

Question 22

How to spot extradural haemorrhage

Answer 22

lemon shaped spot in MRI/CT

Question 23

What causes subdural bleeds

Answer 23

ruptured veins in brain

Question 24

Why are subdural bleeds less dangerous than extradural bleeds

Answer 24

Extradural due to high pressure arterial bleed , subdural is a venous bleed at lower pressure so less blood loss

Question 25

What should you do clinically with a patient who might have a subdural bleed

Answer 25

Keep patient in hospital overnight and monitor esp if head injury causes confusion / loss of consciousness as subdural bleeds present with delayed symptoms that can present overnight

Question 26

What causes subarachnoid bleeds

Answer 26

Ruptured aneurysms ( often in lower brain in circle of willis

Question 27

Risk factors for subarachnoid bleeds

Answer 27

Congenital aneurisms

hypertension

Question 28

Causes of intracerebral bleeds

Answer 28

Spontaneous rupture of artery due to hypertension

Question 29

What is a stroke

Answer 29

type of cerebrovascular accident (CVA) aka rapidly developing focal disturbance of brain function of presumed vascular origin and >24 h duration

Question 30

What causes CVAs ( cerebrovascular accidents

Answer 30

15% haemorrhage

85% thrombo- embolic ( blockage in vessels

Question 31

What are the 4 types of stroke

Answer 31

Ischemic
haemorrhagic
transient ischaemic
thromboembolic

Question 32

What is an ischaemic stroke

Answer 32

occurs when blood flow is blocked by a clot or an embolism

Question 33

What is haemorrhagic stroke

Answer 33

Occurs due to bursting of a blood vessel

Question 34

what is transient ischaemic stoke

Answer 34

Occurs when disruption of circulation to one part of brain due to thromboembolic causes . Resolves in 24h

Question 35

What is a thrombosis

Answer 35

formation of blood clot

Question 36

What is embolism

Answer 36

Plugging of small vessel by material ( atherosclerotic debris) is carried from a larger vessel

Question 37

What is a thromboembolism

Answer 37

formation of a thrombus elsewhere within circulation can be degenerated into an embolus, being carried within circulation into cerebral arteries.
Atherosclerotic debris from the internal carotid artery can further contribute to the development of a thrombo-embolic stroke
An arterial gas embolism can form within blood vessels, and travel into cerebral vasculature, potentially causing a stroke

Question 38

symptoms for stoke

Answer 38

Think FAST 
Face --> cant smile , one side fallen 
Arms --> can't hold them up 
speech --> slurred
time --> call 999

Question 39

Risk factors for stroke

Answer 39

Age 
Hypertension 
Cardiac disease 
Smoking 
Diabetes mellitus

Question 40

What does the anterior, middle and posterior cerebral artery supply

Answer 40

1) ant --> Supplies the para-sagittal midline of the brain and perfuses the occipital fissure
Includes PMC ( premotor cortex) 

2) middle –> supplies a portion of the frontal lobe and the lateral surface of the temporal and parietal lobes + deep structures of the brain
Includes PMC

3) post –> supplying the occipital lobe, in addition to the inferior region of the temporal lobe

Question 41

Symptoms of anterior cerebral artery stroke

Answer 41

Disruption to ACA supply impacts contralateral motor control, subsequently leading to paralysis.
This is due to it effecting the PMC which is sematosensory ( different areas are mapped to different parts of the body)
Topographically, paralysis of the leg > arm, face.
Disturbance of intellect, executive function, and judgement (abulia).
Abulia = broken down frontal function
Loss of appropriate social behaviour (disinhibition).
2 + 3 due to damage to frontal lobe

Question 42

Symptoms of middle cerebral artery stroke

Answer 42

Classic stroke leads to contralateral hemiplegia, topographically affecting the arm > leg.
As effects motor cortex and deep motor association structures
hemiplegia= paralysis on one sde of teh body
Contralateral hemisensory deficits (damage to primary somatosensory cortex residing in the post central gyrus).
Hemianopia ( loss of one half of visual field→ Ocular systems runs back to occipital lobe which can be damaged )
Aphasia (In a left sided lesion): Broca’s and Wernicke’s area affected.

Question 43

Symptoms of post cerebral artery stroke

Answer 43

A stroke will lead to visual deficits: Homonymous hemianopia (One side) and visual agnosia (inability to recognise).
Due to damage to occipital lobe so loss of visual field and processing
Prosopagnosia is a cognitive disorder of face perception. ( aka inability to recognise faces of ppl you’ve known for a long time)