Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

neuro lectures > motor control 1 > Flashcards

motor control 1 Flashcards

1
Q

types of motor control

A

voluntary
goal directed
habit
involuntary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

examples of voluntary motor control

A

running
walking
talking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is goal directed motor control

A

conscious
explicit
controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is habit motor control

A

unconscious
implicit
automatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is involuntary motor control

A

eye movements
facial expression,jaw,
tongue,
postural muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe activation of muscle fibres

A

its either all or none

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how is a skeletal muscle attached to the bone

A

by a tendon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is a muscle fascicle

A

a bundle of skeletal muscle fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is skeletal muscle made of

A

several muscle fasiculi (group of muscle fibres)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a muscle fibre made of

A

several myofibrils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what do myofibrils contain

A

protein filaments; actin & myosin myofilaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what happens when a muscle fibre is depolarised

A

actin and myosin slide against each other and produce muscle contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define motor unit

A

a motoneuron and all of its associated muscle fibers that it innervates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

is an alpha motor neurone an upper or lower motor neurone

A

lower motor neurone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe muscle fibres in a single motor unit

A

located in one muscle but they are distributed throughout the muscle and are not necessarily adjacent to each other

this is to provide evenly distributed force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

do different motor neurones innervate different numbers of muscle fibres

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does it mean if a motor neurone innervates less fibres

A

greater variation of movement
eg fingertips and tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does activation of an alpha motor neurone cause

A

depolarisation and contraction of all the fibres in that unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the final common pathway for motor control

A

the motor unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

the more a motor neurone fires…

A

… the more fibres that contract

resulting in more power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

where are alpha motor neurones controlling distal muscles located

A

laterally in the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

where are alpha motor neurones controlling proximal muscles located

A

medially in the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what does the average number of muscle fibres innervated by a single motor neurone depend on

A

on 2 functional requirements for that muscle

  1. level of control
  2. strength
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

where does the myelin sheath surrounding the axon of each motor neurone end

A

near the surface of a muscle fibre

and the axon divides into a number of short processes that lie embedded in the grooves on the muscle fibre surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what do the axon terminals of a motor neurone contain
vesicles similar to those found in the synaptic junctions between two neurones the vesicles contain the neurotransmitter acetyl-choline (ACh)
26
what is the motor end plate
the region of the muscle fibre plasma membrane that lies directly under the terminal portion of the axon
27
what is the neuromuscular junction
the junction of an axon terminal with the motor end plate
28
what happens when an action potential in a motor neurone arrives at the axon terminal
it depolarises the plasma membrane, opening voltage-gated Ca2+ channels and allowing Ca2+ ions to diffuse into the axon terminal from the extracellular fluid
29
what do Ca2+ ions bind to
to proteins that enable the membranes of the acetyl-choline containing vesicles to fuse with the neuronal plasma membrane, thereby releasing ACh into the extracellular cleft separating the axon terminal and the motor end plate
30
where does ACh diffuse from
diffuses from the axon terminal to the motor end plate where it binds to cholinergic nicotinic receptors
31
what does binding of ACh do
opens an ion channel in the receptor protein (both sodium & potassium can pass through these channels)
32
what is the end-plate potential (EPP)
due to the differences in the electrochemical gradients across the plasma membrane, MORE Na+ moves in than K+ out - producing a local depolarisation of the motor end plate the end-plate potential (EPP) (this is equivalent to an EPSP (excitatory postsynaptic potential) at a neuron-neuron synapse
33
compare magnitudes of EPP and EPSP
the magnitude of a single EPP is much larger than that of an EPSP because the neurotransmitter is released over a larger surface area, thereby binding to many more receptors and opening many more ion channels SO one EPP is more than sufficient to depolarise the muscle plasma membrane adjacent to the end-plate membrane to its threshold potential thereby initiating an action potential
34
where is the action potential propagated
over the surface of the muscle fibre and into the T-tubules (to spread throughout the muscle)
35
where are most neuromuscular junctions located
near the middle of a muscle fibre with newly generated action potentials propagating from this region in both directions towards the ends of the fibre
36
how are action potentials in motor neurones different to synaptic junctions
EVERY ACTION POTENTIAL in a motor neurone normally produces an action potential in each muscle fibre in its motor unit - whereas in synaptic junctions multiple EPSPs must occur in order for threshold to be reached and an action potential elicited in the postsynaptic membrane
37
are all neuromuscular junctions excitatory
yes
38
which enzyme is present in the synaptic junction of the neuromuscular junction
acetylcholinesterase - breaks down ACh - the choline is then transported back into the axon terminals where it can be used for the synthesis of new ACh
39
what are muscle spindles
delicate sensory receptors that inform the CNS about changes in 1. the length of individual muscles 2. the speed of stretching receptors in the spindle will detect stretch regardless of the current muscle length
40
structure of stretch receptors
consist of peripheral endings of afferent nerve fibers wrapped around modified muscle fibers
41
what are intrafusal fibres
The modified muscle fibres within the spindle
42
what are the 2 ends of intrafusal fibres innervated by
GAMMA MOTOR NEURONES (type of lower motor neurone)
43
what do gamma motor neurones do
keep the intrafusal fibres set at a length that optimises muscle stretch detection
44
what part of muscle spindle is contractile
the two ends of the muscle spindle are contractile whilst the central portion is non-contractile
45
how many types of stretch receptor are there in the spindle
2
46
what are the 2 types of stretch receptors
1. nuclear chain fibres 2. nuclear bag fibres
47
what do nuclear chain fibres respond to
to how much muscle is stretched
48
what do nuclear bag fibres respond to
both the magnitude of stretch AND the speed with which it occurs
49
what is the middle third of the spindle associated with
fast type 1a afferent sensory nerves
50
what are the inferior and superior thirds of the spindle associated with
slower conducting type 2 afferent sensory nerves
51
describe arrangement of muscle spindle in regards to extrafusal fibres
muscle spindles are attached by connective tissue in parallel to the extrafusal fibers
52
what activates receptor endings of intrafusal fibres
an external force stretching the muscle pulls on the intrafusal fibers, stretching them and activating their receptor endings
53
impact of more or faster stretching of a muscle
greater rate of receptor firing
54
what happens if action potentials along motor neurons cause the contraction of extrafusal fibers
the resultant shortening of the muscle removes tension on the spindle and thus slows the rate of firing in the stretch receptor - thereby resulting in a reduction of sensory information
55
what is used to prevent loss of sensory information
alpha-gamma coactivation
56
how does alpha gamma coactivation work
1. the contractile ends of the intrafusal fibers are too small & weak to contribute to force or shortening of the entire muscle 2. However, they can maintain tension and stretch in the central receptor region of the intrafusal fibre 3. so activating the gamma-motor neurones ALONE will increases the sensitivity of the muscle to stretch 4. Coactivating BOTH the alpha and gamma motor neurones will prevent the central region of the muscle spindle from going slack during a shortening muscle contraction - ensuring that information about muscle length will be continuously available to provide for adjustment during ongoing actions and to plan and program future movements
57
what does tension depend on (3)
- muscle length - the load on the muscles - the degree of muscle fatigue
58
why is tension feedback necessary
to inform the motor control system of the tension actually achieved
59
how is tension feedback provided
- some provided by vision (you can see whether you are lifting or lowering an object) - some by afferent input from the skin, muscle & joint receptors
60
what are the golgi tendon organs
a receptor type that specifically monitors how much TENSION the contracting motor units are exerting (or is being imposed on the muscle by external forces if the muscle is being stretched) - they measure the force developed by the muscles & any resultant change in length
61
structure of golgi tendon organs
they are endings of afferent fibres that wrap around collagen bundles in the tendons near their junction with the muscles - these collagen bundles are slightly bowed in their resting state
62
what are the afferent fibres leading from the golgi tendon organ to the spinal cord
1b fibres that run to the anterior horn of the spinal cord
63
what causes tension to be exerted on the tendon
when the muscle is stretched or the attached extrafusal muscle fibres contract - tension is then exerted on tendon this straightens the collagen bundles and distorts the golgi tendon receptor endings thereby activating them
64
what causes the tendon to stretch more
the tendon is stretched much more by an active contraction of the muscle than when the whole muscle is passively stretched - thus golgi tendon organs discharge in response to the tension generated by the contracting muscle and initiate action potentials that are transmitted to the CNS
65
what is the INVERSE STRETCH (MYOTATIC) REFLEX
Branches of the afferent neurone (1b fibres) from the golgi tendon organ cause the inhibition of ALPHA MOTOR NEURONES of the contracting muscle (thereby inhibiting muscle contraction) and its synergists (muscles whose contraction assists the intended motion) via interneurons in order to regulate muscle tension at a normal range and to protect it from overload
66
what is the output produced by the golgi tendon proportional to
muscle tension (force)
67
do golgi tendon organs possess slower or faster afferent fibres than muscle spindles
slower
68
what else do golgi tendon organs stimulate
the motor neurones of the antagonistic muscles
69
what are Pacinian corpuscles
(occur in the skin & deep tissue) detect vibrations

neuro lectures (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions