Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Functional Neuroanatomy > W6 - LMNs, Motor Units + Reflex Arc > Flashcards

W6 - LMNs, Motor Units + Reflex Arc Flashcards

1
Q

What 2 patterns of muscular contractions produce movement?

A

Spatial and temporal

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

LMNs send axons out of the … and … to innervate skeletal muscles for the head + body respectively

A

Bst (head), SC (body)

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

What is the major source of input to the LMNs?

A

Interneurons

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

Interneurons are only found in the…

A

CNS

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

Interneurons act a connector between…

A

Sensory and motor systems

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

Local interneurons have short axons what do they connect with?

A

Local, nearby neurons only

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

Relay interneurons have long axons, what do these tracts connect?

A

Separate regions of the brain

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

What are the relay and local interneurons important for?

A

Relay - learning and decision making, Local - synchronised muscle movement

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

What two NTMs are used by interneurons?

A

GABA and glutamate

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

Interneurons are multipolar, what does this mean?

A

They synapse onto multiple neurons

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

LMNs are motor neurons in the SC and Bst that directly innervate …

A

Skeletal muscle contraction

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

What is a motor neuron pool?

A

All the LMNs that innervate a particular muscle

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

There are two types of LMNs found in MN pools, what are they and what do they innervate?

A

Alpha LMN - innervate extrafusal muscle fibres, Gamma LMN - innervate extrafusal muscle fibres

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

What is a motor unit?

A

The individual alpha motor neuron and the extrafusal fibres it innervates

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

What are the 3 motor unit subtypes and say them in the order recruited?

A

Slow, fast fatigue resistant, fast fatigable

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

What motor unit would be used for low effort, sustained movements like posture?

A

Slow MU

17
Q

What action would fast contracting, fatigue resistant MUs be used for?

A

Walking (intermediate movements)

18
Q

What would fast contracting, fast fatigable MUs be used for?

A

Actions of brief exertion e.g. sprinting

19
Q

Distinctions between MU explain how the NS produces movements appropriate for certain circumstances, what is different between the MU in the gastrocnemius (sudden movement) compared to the soleus (posture)?

A

Gastro alpha motor neurons innervate many more muscle fibres than the alpha MN in the soleus

20
Q

What is the size principle?

A

Increasing or decreasing the number of MU active to change the amount of force produced

21
Q

Low frequencies of stimulation causes AP in motor neurons to produce a single twitch, higher frequencies result in … summation and what type of tetanus?

A

Temporal, unfused tetanus

22
Q

When the rates of motor neuron activation is at it’s highest, there is a fused tetanus response, what is this?

A

A response where individual twitches are no longer apparent

23
Q

Muscle spindles comprise of 8-10 intrafusal fibres parallel to the extrafusal MFs, what are the two classes of intrafusal fibres?

A

Nuclear bag fibres and nuclear chain fibres

24
Q

What differs between the nuclear bag fibres and nuclear chain fibres?

A

Sensitivity to stretch

25
Q

Is there more nuclear bag fibres or nuclear chain fibres?

A

More nuc chain fibres

26
Q

Muscle spindles are specialised sensory organs, what type of information do they provide to show muscle length?

A

Mechanosensory

27
Q

Group 1a and 2 afferents (gamma MNs) are associated with different parts of the intrafusal MFs, what are these parts?

A

1a - coil around central part of each class of IFMF, 2 - form secondary endings mainly on nuclear chain fibres

28
Q

Stretch imposed on the muscle deform IFMFs, how does this tell the brain of this stretch?

A

Activate mechanically gated ion channels in afferent axons that innervate the spindle, producing APs

29
Q

Most muscle spindles fire APs spontaneously and steadily when the muscles rest, what happens when the muscle is stretched?

A

A brief increase in rate of APs firing

30
Q

How to measure APs in real time?

A

Use of EMG

31
Q

G-motor neurons regulate gain of muscle spindles so they can operate efficiently at any muscle length, if they are activated alongside

A
32
Q

Golgi tendon organs are encapsulated ….. nerve endings located at the junction of a muscle + tendon, what do they provide info about?

A

Afferent, provide info about muscle tension

Functional Neuroanatomy (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions