Motor Sytems - Spinal Cord

Question 1

What are the three categories of movements?

Answer 1

Reflexive

Rhythmic

Voluntary

Question 2

What are the three things the spinal cord?

Answer 2

1) carries motor information from the brain to the periphery
2) carries sensory information from periphery to the brain
3) mediates reflexes for body

Question 3

What is in the gray matter?

Answer 3

Nerve cell bodies, dendrites and axons

Question 4

What is in the white matter?

Answer 4

Bundled of myelinated axons organized into tracts (pathways)

Question 5

What are the types of neurons in the gray matter?

Answer 5

• dorsal horn: mainly neurons responding to sensory inputs
• ventral horn: mainly motor neurons whose axons exit the spinal cord
• Intermediate gray: some sensory neurons, some motor neurons, inter neurons

Question 6

What is a motor unit?

Answer 6

One alpha motor neuron and all the muscle fibers it innervates

Question 7

What is a motor neuron pool?

Answer 7

The collection of aloha motor neurons that innervates a single muscle

Question 8

What are the two types of lower motor neurons in the spinal cord?

Answer 8

1) Alpha Motor neurons
- innervates extrafusal muscle
- trigger the generation of force in the muscle

2) gamma motor neurons
Innervate intra fusal muscle fibers of the muscle spindle

Question 9

What does volunteer contraction of skeletal muscle require?

Answer 9

Interaction of 2 neurons: an upper motor neuron and a lower motor neuron