Lecture 9

Question 1

Arteries of the anterior system

Answer 1

• left internal carotid
• right internal carotid
• middle cerebral artery
• anterior communicating artery
• anterior cerebral artery

Question 2

arteries of the posterior system

Answer 2

• left and right vertebral artery
• posterior cerebral artery
• anterior spinal artery
• basilar artery
• anterior inferior cerebellar artery
• posterior inferior cerebellar artery
• pontine arteries

Question 3

where do the below arteries of the posterior system supply?

• Superior cerebellar artery
• Basilar artery
• Pontine arteries
• Anterior inferior cerebellar artery
• Posterior inferior cerebellar artery

Answer 3

• sup. cerebellum, sup. pons, and inf midbrain
• anterior pons
• anterior pons
• ant. inf. cerebellum, and inf. pons
• post. inf. cerebellum and lateral medulla

Question 4

blockage of what artery leads to locked in syndrome

Answer 4

basilar artery (block to anterior pons)

Question 5

Where do the below arteries of the anterior system supply?

• anterior cerebral artery
• middle cerebral artery

Answer 5

• medial surface of cerebral hemisphere, medial frontal and parietal lobes and corpus callosum
• lateral surface of cerebral hemisphere and basal ganglia

Question 6

The left and right anterior cerebral arteries are connected by a small artery called the ?

Answer 6

anterior communicating artery

Question 7

The common carotid artery branches off to form _____?The subclavian arteries branch off to form ______?

Answer 7

Internal carotid arteries –> supplying anterior system

Vertebral arteries —> supplying posterior system

Question 8

Damage to the anterior cerebral artery leads to

Answer 8

1) Somatosensory- motor deficits of legs on the contralateral side
2) Prefrontal cortex–> cog deficits (personality changes & problems with EF)

Question 9

Damage to the middle cerebral artery leads to

Answer 9

1) Somatosensory- motor deficits of arms on the contralateral side
2) left hemisphere–> Expressive aphasia (frontal lobe- Broca)/ receptive aphasia (temporal lobe- Wernickes)
3) Right parietal lobe–> left neglect syndrome
4) Prefrontal cortex–> cog deficits (personality changes & problems with EF)

Question 10

The vertebral arteries give rise to what 3 branches?

Answer 10

1) Posterior spinal artery
2) Anterior spinal artery
3) Posterior inferior cerebellar artery (PICA)

Question 11

The posterior spinal artery supplies?

The anterior spinal artery supplies?

Answer 11

Post: posterior 1/3 of spinal cord (dorsal columns)
Ant: Anterior + lateral 2/3 of spinal cord

Question 12

Anterior spinal artery fuses together to form _____, which runs down the ______.

Answer 12

midline artery

anterior median fissure of spinal cord

Question 13

Stroke in the posterior spinal artery leads to

Answer 13

Posterior Cord Syndrome

• loss of discriminative touch, proprioception and vibration on the IPSILATERAL side below level of stroke
• pain and temperature NOT affected

Question 14

Stroke in the anterior spinal artery leads to

Answer 14

Anterior Cord Syndrome:

• loss of motor control below level of stroke
• loss of pain & temperature sensation below level of stroke
• Autonomic fxn often affected

Question 15

Where do the vertebral arteries come together to form the basilar artery?

Answer 15

Junction of the pons & medulla

Question 16

Basilar artery gives rise to (3)

Answer 16

1) Anterior inferior cerebella arteries (AICA)
2) superior cerebellar arteries
3) Many pontine arteries (supply pons)

Question 17

At level of midbrain basilar artery splits to form the ______. What does it supply? What would occur if the structure were damaged?

Answer 17

Two posterior cereBRAL arteries

Supplies occipital lobe and inferior parts of temporal lobe (incl hippocampus)

Damage:

• Occipital lobe: visual deficits in the contralateral visual field (contralateral homonymous hemianopsia)
• Hippocampus: memory deficits

Question 18

The posterior and anterior spinal arteries receive blood from the (2)

Answer 18

1) Vertebral artery

2) Radicular arteries (off the intercostal arteries)

Question 19

The diencephalon and BG receive blood from (3)

Answer 19

1) Medial striate arteries
2) Lateral striate arteries
3) thalamoperforate and thalamogeniculate arteries

Question 20

What connects the anterior system and the posterior system of arteries? What does it form?

Answer 20

Posterior communicating artery

Circe of Willis

Question 21

Describe the benefit of an anastamosis

Answer 21

Provides an alternate route for blood flow in case of blockage of an artery

Question 22

Identify what arteries are included in the circle of Willis (10)

Answer 22

1) Anterior communicating artery
2) Left anterior cerebral artery
3) Left internal carotid artery
4) Left posterior communicating artery
5) left posterior cerebral artery
6) Basilar artery
7) Right posterior cerebral artery
8) Right posterior communicating artery
9) Right internal carotid artery
10) Right anterior cerebral artery

Question 23

Where are the venous sinuses located?

Answer 23

Between layers of dura mater

Question 24

____, ____ and _____ form the confluence of sinuses

Answer 24

superior, straight, occipital sinuses

Question 25

T or F: blood from the transverse and sigmoid sinuses drain into the confluence of sinuses

Answer 25

F: blood --> confluence of sinuses --> transverse --> sigmoid sinus--> jugular foramen

Question 26

T or F: The deep venous system consists of veins that lie next to the arteries in the sulci of the cerebral cortex

Answer 26

F: superficial venous system

Question 27

Describe blood flow of the deep venous system

Answer 27

Centre of brain --> venous sinuses

Question 28

The largest deep vein is _____ and it empties into the _____ sinus.

Answer 28

``` great vein (vein of Galen) straight sinus ```

Question 29

Main function of CFS

Answer 29

cushion the brain

Question 30

Problems with production, circulation and reabsorption of CSF can result in _____

Answer 30

Hydrocephalus : excess CSF leading to increased intracranial pressure

Question 31

CSF is produced in the ____ _____ of all ventricles

Answer 31

Choroid plexus

Question 32

Describe the flow of CSF within the ventricles/ around the brain & spinal cord

Answer 32

CSF flows from the subarachnoid space via - the lateral apertures of the 4th ventricles (foramina of Luschka), - median aperture of the 4th ventricle (foramen of Magendie) - central canal of the spinal cord Reabsorbed by the arachnoid granulations --> emptied into superior sagittal sinus (with venous blood)

Question 33

Describe an ischemic stroke and the various types of atherosclerotic changes

Answer 33

Occluded (blocked) artery shutting off blood supply to a region of the brain Thrombus: blood clot formed within vessel Embolus: foreign matter (blood clot) carried along in the bloodstream

Question 34

Region of dead tissue affected by a stroke

Answer 34

Infarct

Question 35

T or F: Transcient ischemic attack are similar to strokes but symptoms only last for minutes to hours

Answer 35

T (no acute infarct)

Question 36

Rupture of an aneurysm or blood vessel can cause ____ _____

Answer 36

hemorrhagic stroke

Question 37

Malformation of confined large anastomoses between arteries and veins

Answer 37

Arteriovenous malformation (AVM) Tangle = increased risk for bleed

Question 38

Tear to middle meningeal artery can lead to ___ _______, which leads to potential bleeding between ____ and _____. Name symptoms (3)

Answer 38

Epidural hemorrhage dura and skull Sx: 1) headache 2) loss of consciousness 3) possible impingement of CN III // loss of pupillary light reflex

Question 39

T or F: Artery bleeds have higher mortality rates compared to veins. Why?

Answer 39

T: arterial = increased pressure

Question 40

Shearing of the cerebral veins entering the dural sinuses causes ______ ______. Often due to ______.

Answer 40

``` subdural hematoma (between dura & arachnoid- not usually present) trauma --> fluctuating symptoms depending on speed of bleed ```

Question 41

Subarachnoid hemorrhage is caused by bleeding between ____ and ____ . Symptoms (3)

Answer 41

arachnoid pia mater high mortality rate: circle of willis Sx: - headache - loss of consciousness - possible loss of pupillary light reflex (CN III)

Question 42

Bleeding directly into brain tissue

Answer 42

Intracranial hemorrhage | Sx depends on area affected/ size of bleed

Question 43

Sx of subdural hematoma

Answer 43

often seem drunk - headaches - confusion - varies depending on speed/ location of bleed

Question 44

Neuroplasticity plays a role (4) after injury/ disease

Answer 44

development memory learning recovery

Question 45

A strengthening or weakening of the synaptic connections between neurons

Answer 45

Synaptic plasticity

Question 46

3 subcellular mechanisms for synaptic plasticity

Answer 46

Increased or decreased 1) release of neurotransmitter 2) # of neurotransmitter receptors 3) sensitivity of neurotransmitter receptors

Question 47

What is synaptogensesis?

Answer 47

Formation of new synapses Contact between presynaptic & postsynpatic neurons + appropriate molecules = new synapse

Question 48

Regeneration

Answer 48

Damaged axons regrow and re-establish original connections

Question 49

Axon sprouting

Answer 49

Axons from undamaged portions of neurons form new branches

Question 50

Reactive synaptogenesis

Answer 50

synapse formation in response to a stimulus (e.g. damaged neuron)

Question 51

Describe the Wallerian degeneration process

Answer 51

In the PNS the distal portion of the axon will break down and macrophages clean up the debris Meanwhile, the medial (healthy) portion of the axon that is connected to the cell body will heal and begin to regrow

Question 52

What are 2 factors that influence the success of Schwann cells regenerating to original target?

Answer 52

1) intact neurolemmal tube | 2) supply of growth factor

Question 53

Why is it more difficult for regeneration/ axon sprouting to occur in the CNS?

Answer 53

1) Oligodendrocytes do not form a neurolemmal tube 2) inhibitory axon growth effect 3) astrocytes form gliotic scar tissue around damaged area = physical barrier to growth

Question 54

T or F: in adult brains axon sprouting consists of the formation of new pathway formations

Answer 54

F: increase in inputs that already exist

Question 55

What are the 3 neuroplastic changes that can occur in the cerebral cortex?

Answer 55

1) Use- dependent: Learning alters body representation in motor/ sensory cortex - most used = largest representation 2) Connection- dependent: reorganization of cortex based on adjacent muscles being used 3) After damage to brain: adjacent areas or contralesional areas can take over motor control

Question 56

Humans that have an increased somatosensory cortex related to their fingers that read braille is an example of what neuroplastic change?

Answer 56

Use- dependent *motor and sensory maps can change

Question 57

Describe the process of secondary connections becoming "unmasked"

Answer 57

One area of the cortex may have connections to several parts of the body. Therefore when the primary input fibers are damaged, the secondary connections can be unmasked to become the main input. sensory and motor

Question 58

Describe the process of "learned non-use"

Answer 58

reorganization of the map after injury. Eliminating the areas of non-use to be remapped by areas of undamaged use areas --> can limit person's functional recovery // important to still use affected areas Tx: Constraint Induced therapy

Question 59

Factors influencing recovery post stroke

Answer 59

1) size of infarct 2) age 3) rehab - use it or lose it 4) timing and intensity of rehab