Locomotion

Question 1

Know where the repetitive quality of locomotion and the rhythmicity of stepping is controlled.

Answer 1

Repetitive quality – spinal cord or lower levels of nervous system

Rhythmicity – spinal cord

Question 2

Define central pattern generator.

Answer 2

Neural netowrks capable of generating rhythmic motor activity in the absence of sensory feedback.

Question 3

Know three ways burst neurons, or bursters are controlled.

Answer 3

1. Mutual inhibition
2. Rate of recovery
3. Mutual excitation

Question 4

Know three sources of step regulation.

Answer 4

1. Somatosensory input
2. Vestibular input
3. Visual input

Question 5

Know what initiates swing phase in the hind limb.

Answer 5

hip extension which stimulates hip flexors

Question 6

Describe how hip extension initiates swing phase.

Answer 6

Hip flexors are stretched stimulating the Ia fibers of the MSCs. The Ia fibers cause contraction of the flexors (the same muscle) and inhibit the extensors.

Question 7

Know how the body makes sure that swing phase doesn’t start when the leg is weight bearing.

Answer 7

When leg is weight bearing, the GTOs stimulate the extensor motor neurons

Question 8

Define phase dependent reflex reversal.

Answer 8

The same stimulus excites different muscle groups depending on the phase of stride.

Question 9

Know how a little spasticity can be useful.

Answer 9

Jumping – seem to be able to push off the ground with greater force and velocity, increase ground reaction force

Question 10

Describe both negative and positive dissociation.

Answer 10

Negative – front and rear feet are dissociated

Positive – front foot hits the ground after the hind foot

Question 11

Know the effects of extreme positive dissociation.

Answer 11

Walk becomes more lateral like a pace

Question 12

Gait changes are a shift in the coordination between the limbs. Know how this is initiated.

Answer 12

By descending signals from the supraspinal centers and implemented by spinal circuits

Question 13

Know why a horse lowers its center of gravity especially when the base of support is small.

Answer 13

To be more stable

Question 14

Know how horses generate power to run faster or to have more suspension.

Answer 14

High ground reaction force

Question 15

Know three things that make gait more energy efficient.

Answer 15

1. Muscle mass is in proximal limb
2. distal limb folds during swing
3. Light weight distal limb

Question 16

With elbow flexion, what do the carpus, fetlock, and coffin joint do?

Answer 16

Slight flexion

Question 17

Know how the amount of elbow flexion affects stride length and “toe flipping”.

Answer 17

Gives a longer stride with good elevation of the front limb prevents “toe flipping”

Question 18

Know which is more important for soundness, limb deviations in stance or in swing phase.

Answer 18

stance