Neuro 4: Anatomy of blood flow in CNS + Consequences of disruption

Question 1

The brain uses up _____% of cardiac output

Answer 1

10-20%

Question 2

What are the 2 sources of blood supply to the brain?

Answer 2

• internal carotid arteries (front)

- vertebral arteries (back)

Question 3

The 2 sources of blood supply to brain gives rise to network of cerebral arteries called _________

cerebral arteries come off the circle

Answer 3

Circle of Willis.

Question 4

External carotid supplies the ______

Internal carotid supplies the _______

Answer 4

External carotid supplies the face

Internal carotid supplies the cerebral hemispheres

Question 5

Vertebral arteries branch off the ________

and make their way through the _______ ________ (in the cervical vertebrae)

and through the ______ _____ into the brain

Answer 5

Vertebral arteries branch off the subclavian arteries

and make their way through the TRANSVERSE FORAMINA

and through the ________ _______ into the brain

Question 6

What is the ventral view of the brain?

Answer 6

• from underneath

Question 7

the two vertebral arteries at the bottom join together to form the _______ _____

Answer 7

the two vertebral arteries at the bottom join together to form the Basilar Artery

Question 8

The basilar artery bifurcates –> to form the ____ ______ _____

Answer 8

The basilar artery bifurcates –> to form the posterior cerebral arteries

Question 9

The internal carotid arteries travel superiorly, then heads laterally —> forming the ______ _____ ______

and
they also branch to form the ______ ______ _____

Answer 9

The internal carotid arteries travel superiorly, then heads laterally —> forming the middle cerebral arteries

((They emerge through the fissure btw frontal, parietal + temporal lobes))

and they also branch to form the anterior cerebral arteries

Question 10

Why is the arrangement of arteries circular?

Answer 10

• if one side gets occluded, there is still another route for blood to travel.

Question 11

What are the 4 main veins that drain the cerebral hemispheres via the jugular system?

Answer 11

• cerebral veins
• venous sinuses
• dura mater
• internal jugular vein

Question 12

Dural Venous sinuses:

Running along the top, housed between the 2 folds of dura –>

at bottom of dural fold –>

Answer 12

Dural Venous sinuses:

Running along the top, housed between the 2 folds of dura –> Superior Sagittal Sinus

at bottom of dural fold –> Inferior Sagittal Sinus

Question 13

The superior + inferior sagittal sinus runs backwards to form a large blood filled space called –>

Answer 13

The superior + inferior sagittal sinus runs backwards to form a large blood filled space called –> CONFLUENCE OF THE SINUSES

Question 14

DEFINE stroke:

Answer 14

DEFINE stroke:

• rapidly developing focal disturbance of brain function of presumed vascular origin, lasting more than 24 hours

(85% due to infarction, 15% due to hemorrhage)

Question 15

Define Transient Ischemic Attack (TIA)

Answer 15

Define Transient Ischemic Attack (TIA):

• rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hrs

Question 16

What is an infarction?

Answer 16

• degenerative changes that occur in tissues following occlusion of an artery

Question 17

What is Cerebral Ischaemia ?

Answer 17

• lack of sufficient blood supply to the nervous tissue
• -> resulting in permanent damage if blood flow is not restored quickly.

–> due to hypoxia/anoxia

Question 18

What are 2 major causes of Occlusions?

Answer 18

• Thrombosis

- Embolism

Question 19

What are 5 main risk factors for stroke?

Answer 19

• age
• hypertension
• cardiac disease
• smoking
• diabetes mellitus

Question 20

Middle cerebral artery extends laterally

–> supplies __ of the lateral hemisphere

Answer 20

Middle cerebral artery extends laterally

–> supplies 2/3 of the lateral hemisphere

Question 21

The posterior cerebral artery supplies the ____ and ____ parts of the posterior part of the hemisphere.

Answer 21

The posterior cerebral artery supplies the MEDIAL and LATERAL parts of the posterior part of the hemisphere.

Question 22

The anterior cerebral artery supplies the _____ part of the hemisphere

Answer 22

The anterior cerebral artery supplies the medial part of the hemisphere

Question 23

What might happen in disturbance of the anterior cerebral artery?

Answer 23

• paralysis of contralateral leg more common than arms
• disturbance of intellect, executive function + judgement
• loss of appropriate social behavior

Question 24

What might happen in disturbance of the middle cerebral artery?

Answer 24

• “classic stroke”
• contralateral hemiplegia (arm >leg)
• contralateral hemisensory deficits
• hemianopia
• aphasia (L-sided)
• -> can’t speak

Question 25

What might happen in disturbance of the posterior cerebral artery?

Answer 25

PCA supplies the occipital lobe (which has the primary visual cortex)

• this leads to visual defects
• -> homonymous hemianopia
• -> visual agnosia
• -> can’t recognize things you see

Question 26

What is a lacunar infarct?

Answer 26

• stroke causes small holes (lacunae) as brain tissue dies
• occurs due to small vessel occlusion.
• may also occur due to hypertension
• symptoms = dependent on anatomical location of vessel that has been occluded

Question 27

What are the different classifications of haemorrhagic stroke?

Answer 27

• extradural
• subdural
• subarachnoid
• intercerebral

Question 28

How do the different subtypes of hemorrhagic stroke differ?

• extradural
• subdural
• subarachnoid
• intercerebral

Answer 28

EXTRADURAL

• from trauma
• immediate effects

SUBDURAL

• from trauma
• has delayed effects

SUBARACHNOID
- due to ruptured aneurysms

INTRACEREBRAL
- due to spontaneous hypertensive rupture of small vessels

Question 29

What is the difference between dura in the skull and in the vertebral column.

Answer 29

in the VERTEBRAL COLUMN:
- single layer of dura with fat btw bone + the dura

in the SKULL:
- 2 layers of dura

Question 30

What are the 2 layers of dura ?

Answer 30

• periosteal

- meningeal

Question 31

What is the Falx Cerebri

Answer 31

• fold of dura extends between the medial surfaces of the 2 hemisphere.

Question 32

peeling apart of the 2 layers of 2 layers of dura at the top forms the ______ ______ ______

Answer 32

peeling apart of the 2 layers of 2 layers of dura at the top forms the superior sagittal sinus

Question 33

in the superior sagittal sinus, you find the arachnoid granulation which are:

Answer 33

in the superior sagittal sinus, you find the arachnoid granulation which are:

• bursts of subarachnoid space
• that protrudes into the superior sagittal sinus
• CSF leakes through the holes in the arachnoid memb
• and enters the superior sagittal sinus

Question 34

Extradural hemorrhages have a rapid onset due to the rupture of a _____ artery.

Answer 34

Extradural hemorrhages have a rapid onset due to the rupture of a meningeal artery.

Question 35

What is an extradural haematoma?

Answer 35

• high pressure arterial supply to the brain –> leads to splitting of arteries in the meninges themselves
• leads to compression of the skull underneath
• potential space in periosteal dura –> can be filled with blood in extradural hemorrhage

Question 36

Why is subdural hemorrhagic stroke delayed?

Answer 36

• has slower development because:

- it is a lower pressure venous bleed

Question 37

skull isn’t completely closed they might have veins through them e.g

Answer 37

• emissary vein

Question 38

why is antibiotics given in scalp laceration?

Answer 38

there is a chance of infection passing into brain via the emissary vein