Theme 5: Neurophysiology

Question 1

what fibre types are associated with muscle spindle and Golgi tendon organs?

Answer 1

muscle spindle- type Ia/ A-alpha and type II/ A-beta

Golgi tendon organs- type Ib/A-alpha

Question 2

which fibre type is associated with the withdrawal reflex?

Answer 2

type III/ A-delta

Question 3

which fibre type is responsible for pain and temperature sensation?

Answer 3

type IV/ C

Question 4

where is the emotional response to pain produced?

Answer 4

the cingulate gyrus in the limbic system

Question 5

what is the purpose of the crossed extension reflex?

Answer 5

occurs at the same time as the withdrawal reflex to compensate and enhance postural support

Question 6

what function do the type Ia and type II fibres have in the stretch reflex?

Answer 6

type Ia- respond to the velocity of stretch (phasic response)
type II- respond to the degree of stretch (sustained response, tonic firing)

Question 7

what is the purpose of gamma motor neurones in the muscle spindle?

Answer 7

they maintain contraction of the muscle spindle when the stretch reflex occurs snd the muscle contracts so that the muscle spindle remains the same length despite the new length of the muscle. this allows tonic firing to be maintained so it is still sensitive to stretch

Question 8

what is recurrent inhibition?

Answer 8

Alpha motor neurones feedback onto themselves via the renshaw cell (inhibitory interneurone) causing the alpha motor neurone to be inhibited. this prevents the neurone from firing for too long/too often and causing too much contraction

Question 9

what is reciprocal inhibition?

Answer 9

one set of muscles is excited whilst another set is inhibited

Question 10

what is pre-synaptic inhibition?

Answer 10

upper motor neurones act on pre-synaptic neurones via interneurones to inhibit the pathway. occurs in reflex pathways- UMN lesion causes hyperreflexia

Question 11

what is the function of the corticospinal pathway?

Answer 11

voluntary control of musculature

Question 12

what is the function of the corticobulbar pathway?

Answer 12

innervate the motor nuclei of cranial nerves

Question 13

what is the function of the rubrospinal pathway?

Answer 13

excite flexor activity and inhibit extensor activity

Question 14

what is the function of the reticulospinal pathway?

Answer 14

control axial muscles (muscles of the tail trunk and head)

Question 15

what is the function of the vestibulospinal pathway?

Answer 15

assist in postural adjustments and positioning of the head in response to acceleration

Question 16

what is the function of the tectospinal pathway?

Answer 16

control neck movements in response to visual stimuli

Question 17

what are signs of an upper motor neurone lesion?

Answer 17

weakness
spasticity- velocity dependent resistance
hypertonia
hyperrelfexia

Question 18

what are the signs of a lower motor neurone lesion?

Answer 18

weakness 
hypotonia 
flaccid paralysis 
hyporeflexia 
fasciculation's 
atrophy

Question 19

what causes decorticate posturing?

Answer 19

damage to motor pathways above the level of the red nucleus- midbrain, internal capsule, cerebral hemisphere

Question 20

what causes decerebrate posturing?

Answer 20

damage at or below the red nucleus- brainstem, cerebellum, pons

Question 21

what is decorticate posturing?

Answer 21

involuntary flexion of upper extremities caused by excess red nucleus influence
arms are flexed and bent inwards, hands clenched, legs extended and feet turned inward

Question 22

what is decerebrate posturing?

Answer 22

involuntary extension of upper extremities
head is arched back 
arms extended and internally rotated 
wrists extended 
patient is rigid with teeth clenched

Question 23

what is a vegetative state?

Answer 23

wakefulness but absent awareness

Question 24

what is a minimally conscious state?

Answer 24

wakefulness with minimal awareness

Question 25

what are the functions of the reticular formation?

Answer 25

1. sleep and consciousness- reticular activating system
2. somatic motor control- balance, posturing
3. cardiovascular control- cardiac and respiratory centres
4. pain modulation

Question 26

what are the 4 groups of nuclei which form the major part of the reticular activating system?

Answer 26

locus coeruleus
raphe nucleus
ventral tegmental area
basal forebrain

Question 27

which neurotransmitter does the locus coeruleus utilise and what are its functions?

Answer 27

noradrenaline

functions- attention, cortical arousal, sleep-wake cycle, learning, memory and mood

Question 28

which neurotransmitter is associated with the raphe nucleus and what are its functions?

Answer 28

serotonin

functions- sleep-wake cycle, control of mood and emotional behaviour

Question 29

which neurotransmitter is associated with the ventral tegmental area and what are its functions?

Answer 29

dopamine

fucntions- reward behaviour, attention and mood

Question 30

where is the pontomesencephalic nuclei and what neurotransmitter is it associated with?

Answer 30

located at the basal forebrain
acetylcholine
functions- learning, memory and arousal

Question 31

what are the components of the Glasgow coma scale?

Answer 31

eye opening (4- spontaneous, 3- to sound, 2- to pressure, 1- none)
verbal response (5- orientated, 4- confused, 3- inappropriate words, 2- incomprehensible words, 1- none)
motor response (6- obeys commands, 5- moves to localised pain, 4- flexion withdrawal from pain, 3- abnormal flexion (decorticate), 2- abnormal extension (decerebrate), 1- none)