Anatomy and Physiology

Question 1

how many descending white matter tracts are there in the spinal cord?

Answer 1

6

Question 2

what are the two main classifications of descending motor tracts in the spinal cord?

Answer 2

lateral (pyramidal) and ventromedial (extrapyramidal)

Question 3

which motor tracts are lateral/pyramidal tracts?

Answer 3

• lateral corticospinal tract

- rubrospinal tract

Question 4

which motor tracts are ventromedial/extrapyramidal?

Answer 4

• tectospinal tract
• vestibulospinal tract
• medullary reticulospinal tract
• pontine reticulospinal tract

Question 5

what is the function of the tectospinal tract?

Answer 5

it stabilises eyes during movement

Question 6

what is the function of the vestibulospinal tract?

Answer 6

it steadies the head and neck

Question 7

what is the function of the lateral pyramidal tracts?

Answer 7

voluntary control of fine movement

Question 8

what is the function of the reticulospinal tracts?

Answer 8

control of axial muscles for body positioning and posture

Question 9

what is the decussation of the pyramids?

Answer 9

the point in the medullary pyramids where the corticospinal tract fibres cross over to the opposite side

Question 10

where does the rubrospinal tract begin?

Answer 10

in the red nucleus in the midbrain

Question 11

what structure in the brain is the 3rd ventricle associated with?

Answer 11

diencephalon

Question 12

what structure in the brain is the cerebral acqueduct associated with?

Answer 12

midbrain

Question 13

what structure in the brain is the 4th ventricle associated with?

Answer 13

posteriorly - cerebellum

anteriorly - pons and medulla

Question 14

which two motor tracts complement eachother?

Answer 14

corticospinal tract and rubrospinal tract

Question 15

where do the pyramidal tracts originate from?

Answer 15

cerebral cortex

Question 16

where do the extrapyramidal tracts originate from?

Answer 16

brainstem

Question 17

what are the two simultaneous actions of corticospinal tract neurons?

Answer 17

1 - monosynaptic excitation of agonist motor neurons

2- inhibition of antagonist motor neurons (through interneurones)

Question 18

which motor neurons are activated by lateral corticospinal tracts? what action do they carry out?

Answer 18

distal limb muscles - voluntary movement

Question 19

what is the somatotopic distribution of lower motor neurons in the spinal cord?

Answer 19

axial and proximal muscles medially

distal muscles laterally

Question 20

are the actions of the ventromedial motor pathways voluntary or reflexes?

Answer 20

reflexes

Question 21

are the actions of the lateral motor pathways voluntary or reflexes?

Answer 21

voluntary

Question 22

what area of the brain (name and Brodmann area number) is responsible for planning movements?

Answer 22

premotor cortex - Brodmann area 6

Question 23

what do PMA and SMA stand for, and what muscles do they each innervate?

Answer 23

PMA = premotor area - innervates proximal motor units
SMA = supplementary motor area - innervates distal motor units

Question 24

what kind of neurons are found in the corpus striatum?

Answer 24

medium spiny neurones

Question 25

what is the corpus striatum composed of?

Answer 25

caudate nucleus and putamen

Question 26

what actions does firing of the caudate nucleus predict?

Answer 26

eye movements

Question 27

what actions does the firing of the putamen predict?

Answer 27

body/limb movements

Question 28

what are the main steps of the basal ganglia direct pathway? what kind of neurotransmitter signal does each step send?

Answer 28

- cortex to corpus striatum - excitatory (glutamate) - corpus striatum to globus pallidus (internal) - inhibitory (GABA) - globus pallidus to thalamus (VLo) - reduced inhibition - thalamus (VLo) to Area 6 (SMA) - excitatory (glutamate)

Question 29

which area of the thalamus is involved in the basal ganglia pathway?

Answer 29

VLo - ventral lateral nucleus in dorsal thalamus

Question 30

what is the resting state of the thalamus?

Answer 30

inhibited by action of globus pallidus

Question 31

what is the function of the indirect basal ganglia pathway?

Answer 31

to stop antagonistic movements from being activated by the thalamus

Question 32

what is the corticopontocerebellar tract, and what is its function?

Answer 32

a large projection tract from the somatosensory cortex to the pons and cerebellum, involved in motor control

Question 33

which area of the cortex is activated as a result of the direct basal ganglia pathway?

Answer 33

supplementary motor area (SMA)

Question 34

how does cerebellar information get fed back to the SMA for motor control?

Answer 34

cerebellum --> superior cerebellar peduncles --> ventrolateral thalamus --> back to motor cortex

Question 35

which two types of neurons are involved in motor pathways?

Answer 35

upper and lower motor neurons

Question 36

how many different neurons are involved in a sensory pathway?

Answer 36

three - first, second and third order neurons

Question 37

what sensations does the spinothalamic tract carry?

Answer 37

pain and temperature

Question 38

what sensation does the dorsal column tract carry?

Answer 38

proprioception, vibration and light touch

Question 39

what are the three common characteristics of first, second and third order sensory neurons involved in ascending pathways?

Answer 39

- first order neuron always pseudounipolar with a dorsal root ganglion - second order neuron always the one to cross to contralateral side - third order neuron always starts in contralateral medulla

Question 40

what is the crossover point of ascending fibers from the dorsal column?

Answer 40

gracile and cuneate nuclei in medulla

Question 41

what is the crossover point of ascending fibers from the spinothalamic tract?

Answer 41

spinal cord

Question 42

at which level of any ascending pathway does the third order neuron get activated?

Answer 42

at the contralateral thalamus

Question 43

what is the dorsal column tract called after crossover at the cuneate and gracile nuclei?

Answer 43

medial lemniscus

Question 44

which nerve fibres carry pain sensation?

Answer 44

A delta | C fibres

Question 45

name some characteristics of A beta fibers and what sensations they carry

Answer 45

large diameter myelinated mechanoception

Question 46

name some characteristics of A delta fibers and what sensations they carry

Answer 46

``` medium diameter myelinated mechanoception fast pain (nociception) pressure ```

Question 47

name some characteristics of C fibres and what sensations they carry

Answer 47

small unmyelinated carry slow pain temperature (hot)

Question 48

which lamina of Rexed receive pain input?

Answer 48

mainly 2 and 5

Question 49

which system is involved in modulating descending pain pathways?

Answer 49

PAG (periacqueductal grey) pathway

Question 50

what is the gate control theory with regards to pain sensation?

Answer 50

firing of A-beta fibres and PAG fibres may activate inhibitory interneurons, which block the firing of C fibres

Question 51

how does the PAG mechanism modulate pain?

Answer 51

through action at 5HT, NA and opioid receptors

Question 52

what is the difference between pain and nociception?

Answer 52

pain - subjective experience | nociception - physiological stimulus to tissue damage

Question 53

which type of pain (acute or chronic) is physiological?

Answer 53

acute pain

Question 54

define the three types of peripheral sensitisation to pain

Answer 54

allodynia - reduced threshold for nociception hyperalgesia - increased neuronal firing for non-painful stimulus spontaneous pain - independent firing of neurons with no physiological cause

Question 55

define the three types of central sensitisation

Answer 55

wind up: only affects affected synapses, increased firing when stimulus increases, firing stops when stimulus stops classical: new synapses triggered in response to painful stimulus, firing outlasts stimulus long-term potentiation: adaptation of affected synapses as result of repeated stimulus to that area

Question 56

list the three types of central pain sensitisation

Answer 56

wind up sensitisation classical sensitisation long-term potentiation

Question 57

list the three types of peripheral pain sensitisation

Answer 57

allodynia hyperalgesia spontaneous firing

Question 58

what is normally the cause of neuropathy?

Answer 58

nerve damage

Question 59

at which stages of the pain pathway can drugs modulate it?

Answer 59

transduction (peripheral afferents) transmission (to thalamus) response (descending pathway)

Question 60

which two systems are involved in modulating pain, according to the gate control theory?

Answer 60

- A-beta fibre firing | - PAG (periacqueductal grey) and NRM (nucleus raphe magnum) firing

Question 61

which molecules are used to inhibit pain sensation in the gate control theory?

Answer 61

opioid peptides (endorphins)

Question 62

explain the mechanism of action of NSAIDS

Answer 62

they block cyclo-oxygenase, which converts arachidonic acid to prostaglandins

Question 63

explain the mechanism of action of local anesthetics

Answer 63

they block sodium channels, stopping depolarisation of afferent neurons

Question 64

explain the mechanism of action of opiates

Answer 64

desensitise nociceptors trigger inhibitory interneurons in dorsal horn trigger PAG/NRM descending pathway

Question 65

list some chemical triggers found in injured tissue which can activate the pain pathway

Answer 65

``` low pH temperature bradykinin histamine prostaglandins ```

Question 66

what are the three areas of the brain that are essential for forming, accessing and storing memories?

Answer 66

forming - hippocampus accessing - thalamus storing - cortex

Question 67

name the four types of memory

Answer 67

- immediate - short term memory - intermediate term memory - long term memory

Question 68

name the four structures involved in the Papez circuit

Answer 68

- hippocampus - mammillary bodies - thalamus - cingulate cortex