Lecture 6: Spinal Cord Mechanisms Of Motor Control

Question 1

Each muscle fibre is innervated by how many motor axons?

Answer 1

One.

Question 2

Each motor axon innervates how many motor fibres?

Answer 2

They branch to innervate anywhere from 3 to 1000 muscle fibres.

Question 3

What is a motoneuron pool?

Answer 3

The motoneurons controlling an entire muscle.

Question 4

What are two ways in which the strength of a muscle contraction is dictated by?

Answer 4

The frequency in action potentials in motor neurons and the quantity of motoneurons recruited.

Question 5

Which neurotransmitter is present at a neuromuscular junction?

Answer 5

Acetylcholine.

Question 6

Where in the spinal cord are columns of motor neuron pools found?

Answer 6

The ventral horn.

Question 7

Are lateral pathways or ventromedial pathways involved in maintaining posture?

Answer 7

Ventromedial pathways.

Question 8

Are lateral pathways or ventromedial pathways involved in voluntary movement?

Answer 8

Lateral pathways.

Question 9

What do descending motor pathways make use of?

Answer 9

Existing spinal cord circuits.

Question 10

Two sets of pattern generating neurons allow for excitatory and inhibitory impulses that alternate to allow walking. What helps them coordinate their activity?

Answer 10

Inhibitory connections between the two sets of pattern generating neurons.