motor units, muscle spindles, golgi tendon organs and joint receptors Flashcards Preview

Neurology- Week 1 > motor units, muscle spindles, golgi tendon organs and joint receptors > Flashcards

Flashcards in motor units, muscle spindles, golgi tendon organs and joint receptors Deck (27)
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1
Q

What motor neurons make up LMN and what do they do?

A

Alpha motor neurones

Innervate bulk of fibres within a muscl that generate force

2
Q

What is the function of gamma motor neurones

A

Innervate a sensory organ called the muscle spindle

3
Q

Triceps brachii and anconeus msucle work together to produce a force, what name is given to these muscles?

A

Synergistic muscle

4
Q

Biceps brachii and brachialis oppose triceps and anconeus, what name is given to these muscles?

A

Antagonistic muscles

5
Q

How many spinal nerves are there?

A

31 pairs

6
Q

What is a motor unit?

A

An alpha motor neuron and all the muscle fibres it innervates

7
Q

What is a motor neuron pool?

A

All the alpha motor neurones that innervate a single muscle

8
Q

How is force of muscle contraction graded?

A

Frequency of action potential discharge of alpha MN

Recruitment of synergistic motor units

9
Q

How is a muscle twitch sustained into a contraction?

A

Summation of twitches causes a sustained contraction

10
Q

Benefit of a smaller motor unit?

A

Allows for finer movements e.g. extraocular eye muscles

11
Q

How do fast and slow fibres differ?

A

How fast myosin ATPase splits ATP to make energy for cross bridge cycling

12
Q

Features of slow fibres

A
Type 1
ATP from oxidative phosphorylation
Red (High myoglobin)
Slow contract and relax
Fatigue resistant
13
Q

Features of fast (IIa) fibres?

A

fast contract and relax
Oxidative phosphorylation
Fatigue resistant

14
Q

Features of fast (IIb) fibres?

A

ATP from glycolysis
Fast contraction
not fatigue resistant
White

15
Q

What are the 3 types of motor units?

A

Slow
Fast fatiguing
Fatigue resistant

16
Q

Relationship between speed of twitch and size of alpha MN?

A

Fast- large or intermediate

Slow- Small

17
Q

What is the Henneman size principle?

A

Smaller alpha MNs have a lower threshold than larger ones hence slow are more easily activated

18
Q

What is the myotatic reflex?

A

When a skeletal muscle is pulled, it pulls back

19
Q

What does the muscle spindle consist of?

A

Capsule
Intrafusal fibres
Sensory afferents
Gamma MN efferents

20
Q

Describe the myotatic reflex arc

A
Stretch spindle
Activate 1a Afferent
Excitatory synaptic transmission in spinal cord
Activation of alpha MN
Contraction
21
Q

Three types of intrafusal fibres?

A
Bag 1 (dynamic)- sensitive to rate of change of muscle length
Dynamic MN
Bag 2 (Static)- more sensitive to absolute length
Static MN

Chain fibres- absolute length
Static MN

22
Q

Two types of afferent fibres?

A

1a

II, more slowly conducting

23
Q

What are golgi tendon organs?

A

Located at tendon muscle junction

Monitor changes in muscle tension

24
Q

What is the function of golgi tendon organs?

A

Act to regulate muscle tension to protect muscle from overload and regulate at an optimal range

25
Q

What type of fibres innervate golgi tendon organs?

A

1b

26
Q

What are paciniform endings?

A

Found in periosteum near articular attachments and fibrous part of joing capsule
Acceleration detectors

27
Q

What are Ruffini endings?

A

Found mainly in joint capsule

Static postion and speed of movement