Motor Systems

Question 1

Dorsal horn neurons

Answer 1

Sensory neurons

Question 2

Ventral horn neurons

Answer 2

Alpha and gamma motor neurons

Preganglionic sympathetic fibers

Question 3

Alpha motor neurons

Answer 3

Extrafusal (fast)

Question 4

Gamma motor neuros

Answer 4

Intrafusal neurons (slow)

Question 5

Ia sensory neurons

Answer 5

Muscle spindles (fast)

Question 6

Ib sensory neurons

Answer 6

Golgi tendon organ (fast)

Question 7

Spinal cord motor neurons have an somatotropic arrangement
Anterior
Posterior
Medial
Lateral

Answer 7

Anterior: Extensor muscles
Posterior: Flexors
Medial: Proximal muscle
Lateral: Distal limb muscles

Question 8

Safety factor of motor neurons

Answer 8

1

Question 9

In increase in force\contraction is caused by

Answer 9

Recruitment of more motor units

Question 10

Three types of muscle fibers

Answer 10

Red (Type I)
White (Type II)
Intermediate

Question 11

Which fibers fatigue easily

Answer 11

White fibers

Question 12

Which fibers are fatigue resistant

Answer 12

Red fibers

Question 13

Which fibers hold the greatest tension

Answer 13

White

Question 14

Which fibers have the greatest contraction speed

Answer 14

White

Question 15

Which fibers have the greatest aerobic metabolism

Answer 15

Red

Question 16

Fatigue resistant white fibers are called

Answer 16

Intermediate fibers

Question 17

As demand on a muscle increases, what order are muscle fibers recruited

Answer 17

Red, White & Intermediate

Question 18

Function of deep tendon reflex

Answer 18

Triggers muscle contraction when a muscle is excessively stretched

At the same time, muscles that are antagonistic to the contraction are inhibited to allow contraction to take place

Question 19

Deep tendon reflex pathay

Answer 19

1a sensory fiber travels to dorsal horn

Synapses with motor neuron that will result in contraction of overstretched muscle

Question 20

Describe reciprocal inhibition pathway in the deep tendon reflex pathway

Answer 20

1a sensory fiber travels to dorsal horn
Synapses with a interneuron in the integration center
Interneuron synapses and inhibits a motor neuron that causes contraction in antagonistic muscle

Question 21

2 mechanisms to activate intrafusal muscles

Answer 21

1. Muscle contraction

2. Direct gamma motor neuron activation (gamma loop)

Question 22

Muscle contraction mechanism

Answer 22

Muscle contraction results in gamma motor neuron contraction because muscle spindle will reach a new set point to match extrafusal muscle contraction

Question 23

Gamma loop

Answer 23

activate just a few gamma motor neurons that will activate afferents that will then activate the other intrafusal muscle fibers

Question 24

Function of inverse myotatic reflex\golgi tendon reflex

Answer 24

Relax (inhibitory) a muscle in response in response to excessive contraction

At the same time, muscles that are antagonistic to the contraction are stimulated to allow contraction in order to prevent contraction in the muscle undergoing excessive contraction

Question 25

Pathway of inverse myotonic reflex

Answer 25

Sensory 1b neuron travels to dorsal horn
Synapses with an interneuron
The interneuron hyperpolarizes (inhibits) the motor neuron responsible for excessive contraction

Question 26

Describe reciprocal excitatory pathway in the deep tendon reflex pathway

Answer 26

Sensory 1b neuron travels to dorsal horn
Synapses with the interneuron
Interneuron depolarizes (activates) the motor neuron of the antagonistic muscle

Question 27

Function of the withdrawal reflex

Answer 27

Flexion in one limb is accompanied in the contralateral limb

Polysynaptic

Question 28

Spacticity

Answer 28

Overactive gamma motor neuron