Blood Supply to the CNS

Question 1

How much CO goes to the brain?

Answer 1

10-20%

Question 2

How much glucose consumption is done by the brain?

Answer 2

66%

Question 3

2 sources of blood supply to the brain?

Answer 3

Internal carotid arteries

Vertebral arteries

Question 4

Path of the internal carotid arteries?

Answer 4

(internal branch of CC)

Goes through carotid canal in base of skull

Question 5

Path of the vertebral arteries?

Answer 5

(branch of the SCV artery)

Goes through the foramen magnum (as associated w. cervical vertebrae) to fuse and form the basilar artery

Question 6

What protects the vertebral arteries?

Answer 6

Vertebral transverse foramina

Question 7

What part of the brain circulation do the vertebral arteries form?

Answer 7

Posterior circulation (of the brain)

Question 8

What do the internal carotid arteries and vertebral arteries give rise to?

Answer 8

Circle of Willis - anastomotic circuit of vessels that supplies the brain

Question 9

What comes off the Circle of Willis?

Answer 9

Cerebral arteries

LOOK AT ONENOTE PICTURE!!!

Question 10

What part of the brain circulation do the internal carotid arteries form?

Answer 10

Anterior circulation (of the brain)

Question 11

What do the internal carotid arteries go on to become?

Answer 11

Middle cerebral artery

Question 12

What does the basilar artery spilt into to form?

Answer 12

Posterior cerebral artery

Question 13

What does the basilar artery sit infront of?

Answer 13

Pons

Question 14

Which artery goes into the longitudinal fissure between the hemispheres?

Answer 14

Anterior communicating artery

connects L and R anterior cerebral artery across the L.F

Question 15

4 things that mediate venous drainage of the brain

Answer 15

Cerebral veins
Venous sinuses
Dura mater
IJV

Question 16

What forms the venous sinuses?

Answer 16

Falx

Folds of the dura mater (as 2-layers)

Question 17

Where is the blood from the brain drained into?

Answer 17

Into the BACK of the head to the IJV

Question 18

Stroke (or CVA) definition?

Answer 18

Rapidly developing focal disturbance of brain function of presumed vascular origin
AND
of >24 hours duration

Question 19

Two reasons for why a stroke can happen?

Answer 19

Infarction (85%)

Haemorrhage (15%)

Question 20

TIA?

Answer 20

Transient Ischaemic Attack

Question 21

TIA definition?

Answer 21

Rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours

(temporary blockage - warning of a stroke)

Question 22

2 causes of occulusions?

Answer 22

Thrombosis
OR
Embolism

Question 23

5 main risk factors for stroke?

Answer 23

Age
Hypertension
Cardiac disease
Smoking
Diabetes mellitus

Question 24

Part of brain middle cerebral artery is supplying?

Answer 24

Lateral parts of the brain - frontal lobe (large part) and temporal & parietal lobes (lateral surface)

Also supplies sub-cortical grey matter towards centre of brain

Question 25

Part of brain anterior cerebral artery is supplying?

Answer 25

Mid-saggital part of brain - frontal lobes (midline) and parietal lobes (superior medial) [uptil parieto-occipital fissure]

Question 26

Part of brain posterior cerebral artery is supplying?

Answer 26

Occipital lobes

Question 27

What happens if ACA is occluded?

Answer 27

Paralysis of contralateral leg > arm, face (as supplies motor cortex) Disturbance of intellect, executive function & judgement Loss of appropriate social behaviour

Question 28

What happens if MCA is occluded?

Answer 28

''Classic stroke'' Contralateral hemiplegia: arm>leg Contralateral hemisensory deficits (behing central gyrus have 1o sensory cortex) Hemianopia & aphasia

Question 29

What happens if PCA is occluded?

Answer 29

Visual deficits!!! Homonymous hemianopia Visual agnosia

Question 30

Where does lacunar infarcts happen?

Answer 30

Lacune is a small cavity - forms after a stroke as causes these small holes to form in the brain tissue

Question 31

Explain how lacunar infarcts appear

Answer 31

Appear in deep structures as a result of small vessel occlusion

Question 32

Results of a lacunar infarction?

Answer 32

Deficit depends on anatomical location Happens during life - area has often been infarcted and then cleared away (via phagocytosis) leaving a lacuna

Question 33

What are lacunar infarcts associated with?

Answer 33

Hypertension

Question 34

4 different types of haemorrhagic strokes?

Answer 34

Extradural - trauma, immediate effects Subdural - trauma, delayed effects Subarachnoid - ruptured aneurysms Intracerebral - spontaneous hypertensive

Question 35

Extradural bleed?

Answer 35

Due to rupture of meningeal artery - arterial bleed

Question 36

Subdural bleed?

Answer 36

Due to rupture of veins - venous bleed

Question 37

Superior sagittal sinus?

Answer 37

Biggest sinus - CSF leaks into here