A & P - Motor nervous system

Question 1

what does the motor nervous system consist of?

Answer 1

cerebral motor centres
upper motor neurones (UMN)
lower motor neurones (LMN)

Question 2

in which direction is afferent information sent?

Answer 2

from muscles and sensors to CNS (sensory nervous system)

Question 3

in which direction is efferent information sent?

Answer 3

from the CNS to muscles (motor nervous system)

Question 4

what are the functions of the cerebral motor centres?

Answer 4

involved in planning, initiation and regulation of movement

Question 5

name the cerebral motor centres

Answer 5

primary motor cortex (+ pre-motor)
basal ganglia
cerebellum
brainstem
spinal cord

Question 6

where are upper motor neurones located?

Answer 6

cell body of neurone is in primary motor cortex and synapse onto LMN in spinal cord

Question 7

where are lower motor neurones located?

Answer 7

cell body in grey matter of spinal cord synapse with muscle

Question 8

what function does the cerebellum have in the motor nervous system?

Answer 8

balance
posture
locomotion
makes adjustments to movement
manual dexterity

Question 9

what function do the pre-motor areas have in the motor nervous system?

Answer 9

plan complex movement

coordinates movement

Question 10

what function does the primary motor cortex have in the motor nervous system?

Answer 10

initiates voluntary muscle movement
skilled movements
somatotopic

Question 11

what function does the basal ganglia have in the motor nervous system?

Answer 11

associated movements
facilitates wanted movements
suppresses unwanted movements

Question 12

what is the function of the UMNs?

Answer 12

transmit commands from motor cortex to LMNs

Question 13

UMNs form descending tracts, where?

Answer 13

in white matter of spinal cord

Question 14

what do UMNs do in the spinal cord?

Answer 14

decussate (cross over) to the opposite side

Question 15

which part of the motor nervous system can be found in the grey matter of the spinal cord?

Answer 15

cell bodies of MN
interneurons
neuroglia

Question 16

which part of the motor nervous system can be found in the white matter of the spinal cord?

Answer 16

myelinated and unmyelinated axons organised into ascending and descending tracts

Question 17

under what control are the motor neurones in the descending tracts of the spinal cord?

Answer 17

somatic

autonomic

Question 18

which tracts form the cortico-bulbar tract?

Answer 18

lateral cortio-spinal tract

anterior cortio-spinal tract

Question 19

which tract is involved in he cortio-spinal pathway and what is its function?

Answer 19

cortico-bulbar tract

conscious control of skeletal muscle

Question 20

where are the cell bodies of the UMNs in the cortio-spinal pathway located and what is their destination?

Answer 20

cell bodies : primary motor cortex

destination : spinal cord LMNs

Question 21

where in the spinal cord are the cell bodies of LMNs found?

Answer 21

grey matter (ventral horn)

Question 22

describe the journey of an impulse from along the LMN to the muscle fibre

Answer 22

1. myelinated axon exits spinal cord via ventral root
2. travels to muscle via peripheral nerve
3. On entry to muscle axon splits and synapses with muscle fibre at NMJ

Question 23

what does a motor unit consist of?

Answer 23

single LMN and all the muscle fibres it innervates

Question 24

what do small motor units allow for?

Answer 24

fine control movement (eg. eye)

Question 25

what do large motor units allow for?

Answer 25

strength

Question 26

how many muscle units innervate 1 muscle fibre?

Answer 26

1

Question 27

up to how many LMNs can innervate a single muscle?

Answer 27

100

Question 28

what clinical assessments might be used to judge motor neurological functioning?

Answer 28

observation - posture, symmetry coordination, balance, proprioception muscle strength - resistance to applied force muscle tone - resistance when joints moved passively deep and superficial reflexes

Question 29

what is clonus?

Answer 29

rhythmic, involuntary muscle contractions when stretching

Question 30

how is muscle strength regulated and which is the most important?

Answer 30

1. number of active motor units - recruitment 2. frequency of action potential - reduced frequency (brief force, twitching)/ increased frequency (sustained increased force (tetani) RECRUITMENT is most important

Question 31

what is the 'simple' tendon jerk reflex?

Answer 31

single, fast monosynpatic reflex

Question 32

can the 'simple' tendon jerk reflex persist after spinal cord section?

Answer 32

yes

Question 33

what modulates the 'simple' tendon jerk reflex?

Answer 33

higher cerebral centres

Question 34

what is reciprocal inhibition?

Answer 34

during the stretch reflex the antagonist muscle is often inhibited.

Question 35

how can the withdrawal reflex be tested?

Answer 35

plantar reflex | Babinski sign

Question 36

what is the withdrawal reflex?

Answer 36

complex poly-synaptic reflex with longer latency

Question 37

when is the withdrawal reflex seen?

Answer 37

in response to pain stimulus

Question 38

what is the withdrawal reflex sometimes accompanied by?

Answer 38

cross extension of extensor muscles in contralateral leg (avoids fall)

Question 39

what is the withdrawal reflex modulated by?

Answer 39

stimulus intensity

Question 40

what can nervous motor system lesions cause?

Answer 40

muscle weakness - loss of power/strength | paralysis - complete or partial

Question 41

what does the following terms mean? hemiplegia, quadriplegia, paraplegia?

Answer 41

hemiplegia - one sided paralysis quadriplegia - all four limb paralysed paraplegia - lower body paralysis

Question 42

what is the difference between myopathy and neuropathy?

Answer 42

myopathy - affects muscle fibres | neuropathy - LMN axon and/or cell body

Question 43

where can LMN lesions be found?

Answer 43

muscle fibres | LMN axon and/or cell body

Question 44

what are the symptoms of LMN lesions?

Answer 44

muscle weakness/loss of function muscle wasting fasciculation reduced muscle tone and reflexes

Question 45

what is fasciculation?

Answer 45

involuntary muscle movements

Question 46

give an example of a muscle fibre disease (myopathy)

Answer 46

muscular dystrophy

Question 47

given an example of motor neurone disease

Answer 47

amyotrophic lateral sclerosis

Question 48

what is Bell's Palsy?

Answer 48

inflammation of the peripheral nerves

Question 49

what is Sciatica?

Answer 49

compression of peripheral nerves

Question 50

where can UMN lesion be found?

Answer 50

axons in descending tract of spinal cord | cell bodies in motor area of brain

Question 51

what are the symptoms of UMN lesions?

Answer 51

``` increased muscle tone muscle paralysis/weakness no muscle wasting increased stretch reflexes no fasciculation contralateral signs ```