motor and neuromuscular control

Question 1

what is meant by hierarchical organisation in motor control

Answer 1

high order areas of hierarch are involved in more complex tasks e.g coordinating muscle movement
lower level areas perform lower level tasks e.g execution of movement

Question 2

what is meant by functional segregation in motor control

Answer 2

motor system is organised in number of different area that control diff aspects of movement

Question 3

what are the major descending tracts

Answer 3

pyramidal tracts - corticospinal and corticobulbar
extrapyramidal -
vestibulospinal, tectospinal, reticulospinal,rubrospinal

Question 4

what makes a tract pyramidal

Answer 4

pass through pyramids of medulla

Question 5

what is the pathway for pyramidal tracts

Answer 5

motor cortex to spinal cord or cranial nerve nuclei in brainstem

Question 6

what is the pathway for extrapyramidal tracts

Answer 6

brainstem nuclei to spinal cord

Question 7

where is primary motor cortex located

Answer 7

precentral gyrus

anterior to central sulcus

Question 8

what is role of motor cortex

Answer 8

controls fine, discrete, precise voluntary movements

provides descending signals to execute movement

Question 9

where is premotor cortex located

Answer 9

anterior to primary motor cortex

Question 10

what is role of premotor cortex

Answer 10

involved in planning movement

regulates externally cued movements e.g seeing picking up object

Question 11

where is supplementary motor area located

Answer 11

anterior and medial to primary motor cortex

Question 12

what is role of supplementary motor area

Answer 12

involved in planning complex movements, internally cued e.g speech

Question 13

what is the pathway in corticospinal tract and what muscles are involved

Answer 13

upper motor neurones in cortex travel down to medulla where 85-90% of fibres decussate and innervate limb muscles = lateral corticospinal tract
10-15% are uncrossed fibres which innervate trunk muscles = anterior corticopinal tract

Question 14

what is corticobulbar tract responsible for

Answer 14

providing voluntary movements of face mostly and neck muscles too

Question 15

what is role of vestibulospinal tract

Answer 15

stabilise head during body movements
coordinate head movements with eye movement
mediate postural adjustments

Question 16

what is the role of reticulospinal tract

Answer 16

= most primitive descending tract, from medulla and pons

responsible for changes in muscle tone associated with voluntary movement and postural stabilty

Question 17

what is tectospinal tract responsible for

Answer 17

originates from superior colliculus of midbrain

orientation of head and neck during eye movements

Question 18

what is rubrospinal tract responsible for

Answer 18

originates from red nucleus of midbrain
mainly taken over by corticospinal tract
innervate lmn of flexors of upper limb
* comes into play when lesions to cns

Question 19

what are the negative (loss of function) signs caused by upper motor neurone lesion

Answer 19

loss of voluntary motor function
paresis - graded weakness of movements
paralyis (plegia) - complete loss of voluntary muscle activity

Question 20

positve signs (unwanted) sign of umn lesion

Answer 20

increased abnormal motor function due to loss of inhibitory descending inputs
spasticity - increased muscle tone
hyper-reflexia - exaggerated reflexes
clonus - abnormal muscle contractions
babinskis sign

Question 21

what is apraxia

Answer 21

disorder of skilled movement
lesion of inferior parietal lobe and frontal lobe
stroke and dementia are most common causes

Question 22

what can a lower motor neurone cause

Answer 22

weakness
hypotonia
hyporeflexia
muscle atrophy
muscle atrophy
fasiculations - twitching
fibrillations - spontaneous twitching of individual muscle fibres

Question 23

what is motor neurone disease

Answer 23

progessive neurodegenerative disorder of motor system
affects both umn and lmn
aka amyotrophic lateral sclerosis

Question 24

what are the umn signs of mnd

Answer 24

spacticity
brisk limb and jaw reflexes
babinski sign
loss of dexterity
dysarthria - difficulty swallowing
dysphagia - difficulty swallowing

Question 25

what are some lmn signs of mnd

Answer 25

``` weakness muscle wasting tongue fasciculations and wasting nasal speech dysphagia ```

Question 26

what structures make up the basal ganglia

Answer 26

caudate nucleus lentiform nucleus (putamen and external globus pallidus) nucleus accumbens subthalamic nuclei ventral pallidum,claustrum,nucleus basalis thalamus amygdala

Question 27

what is the function of basal ganglia

Answer 27

- decision to move - elaborating associated movements e.g swinging arms when walking - moderating and coordinating movement - performing movements in order

Question 28

what is parkinsons disease

Answer 28

degeneration of dopiminergic neurones that originate in substantia nigra to striatum

Question 29

signs/symptoms of parkinsons

Answer 29

``` bradykinesia - slow movement hypomimic face - emotionless akinesia rigidity tremor at rest ```

Question 30

what is huntingtons disease

Answer 30

degeneration of GABAnergic neurones in striatum,caudate and putamen

Question 31

what does huntingtons disease cause

Answer 31

choreic movemtns - dance rapid jerky involuntary movements of body,hands and leg first and then rest of body speech impairment dysphagia unsteady gait later stages - cognitive decline and dementia

Question 32

what is ballism

Answer 32

usually from stroke affecting subthalamic nucleus sudden uncontrolled flinging of extremitis symptoms occur contralaterally

Question 33

what is cerebellum

Answer 33

located in posterior cranial fossa separated from cerebrum above by tentorium cerebelli coordinator and predictor of movement

Question 34

what is the vestibulocerebellum

Answer 34

part of cerebellum regulation of gait,posture and equilibrium coordination of head movements with eye movemt

Question 35

what can damage to vestibulocerebellum cause

Answer 35

syndrome similar to vestibular disease leading to gait ataxia and tendency to fall

Question 36

what is the spinocerebellum

Answer 36

responsible for coordination of speech adjustment of muscle tone coordination of limb muscles

Question 37

what can damage to spinocerebellum cause

Answer 37

degeneration and atrophy related with chronic alcoholism | affects mainly legs, causes abnormal gait and stance

Question 38

what is the cerebrocerebellum

Answer 38

coordination of skilled movements cognitive function,attention,processing language emotional control

Question 39

what can damage to cerebrocerebellum cause

Answer 39

damage to arms/skilled coordinated movements(tremor)and speech

Question 40

what are the main signs of cerebellar disorders

Answer 40

``` ataxia - impairments in coordination dysmetria - inappropriate force intentional tremor dysdiadochokinesia - inability to perform rapidly alternating movements scanning speech - staccato ```

Question 41

what are alpha motor neurones

Answer 41

- lower motor neurons of brainstem and spinal cord - occupy anterior/ventral horn of grey matter of spinal cord - innervate the extrafusal muscle fibres of skeletal muscle

Question 42

what does activation of alpha motor neurones cause

Answer 42

muscle contraction

Question 43

what is a motor neurone pool

Answer 43

all the alpha motor neurones which go to an individual muscle

Question 44

what is a motor unit

Answer 44

a single motor neurone together with all the muscle fibres that it innervates = smallest functional unit

Question 45

on average how many muscle fibres does each motor neurone supply

Answer 45

600

Question 46

what does small innervation ratio allow

Answer 46

small fine precise control of that muscle

Question 47

what are the 3 types of muscle fibres

Answer 47

slow type - s,1 fast, fatigue resistant, - fr,2a fast, fatiguable - ff, 2b

Question 48

describe slow motor unit muscle fibres

Answer 48

smallest diameter cell bodies small dendritic trees thinnest axons slowest conduction velocity

Question 49

describe fast muscle fibres

Answer 49

large diameter cell bodies large dendritic trees thicker axons faster conduction velocity

Question 50

what are motor unit types classified by

Answer 50

amount of tension generated, speed of contraction and fatiguability

Question 51

how else can cns regulate force produced

Answer 51

recruitment of number of neurones and rate coding/firing

Question 52

what is meant by the 'size principle'

Answer 52

smaller units are recruited first generating small amounts of force and more are recruited if more force is required

Question 53

what happens when firing rate increases

Answer 53

force produced by unit increases

Question 54

what are neurotrophic factors

Answer 54

are a type of growth factor prevent neuronal growth promote growth of neurons after injury

Question 55

what is the reason behind plasticity of motor units/muscle fibres

Answer 55

fibre types can change properties under different conditions e.g type of nerve innervating them

Question 56

what is the most common muscle fibre type change

Answer 56

fast fatiguable to ffr | 2b to 2a

Question 57

when can changes from type 1 to 2 occur

Answer 57

cases of severe deconditioning / spinal cord injury | microgravity during spaceflight can result in shift from slow to fast type muscle fibres

Question 58

what is ageing associated with

Answer 58

loss of type 1 and 2 | more type 1 fibres in aged muscle

Question 59

what is a reflex function

Answer 59

automatic response to stimulus that involves nerve impulse passing inward from nerve centre then outward to effector without reaching level of consciousness

Question 60

jendrassik manoevre

Answer 60

larger reflex when patellar tendon tapped | works by reducing inhibition of brain action

Question 61

what is hyper- reflexia

Answer 61

overactive reflexes loss of descending inhibition associated with UMN lesions

Question 62

what is clonus

Answer 62

involuntary and rhythmic muscle contractions | loss of descending inhibition

Question 63

what is babinskis sign

Answer 63

stimulate sole of foot with blunt instrument curling upwards is abnormal associated with umn lesion

Question 64

what is hyporeflexia

Answer 64

below normal/ absent reflexes | associated with lmn disease