Functional Hierarchy System

Question 1

What is direct control of muscles via?

Answer 1

alpha motoneurones in the spinal cord

Question 2

Where do reflexes occur?

Answer 2

Autonomously at each segmental spinal level

Question 3

What 4 systems control movement?

Answer 3

Descending control pathways from UMN
Basal ganglia
cerebellum
Local spinal cord and brain stem circuits

Question 4

What do LMN at spinal levels directly innervate?

Answer 4

Muscles to initiate reflex and voluntary movements

Question 5

What do lesions to LMN cause?

Answer 5

Flaccid paralysis
Muscles atrophy
Decreased reflexes

Question 6

Where do UMN synapse with?

Answer 6

With multiple lower circuit neurons to regular alpha moto neurone activity

Question 7

Where does the spinal cord receive descending input from?

Answer 7

Neurons in the brainstem

And directly from the corticospinal tract

Question 8

At which level does sensory input enter?

Answer 8

At all levels

Question 9

Name a stretch reflexes

Answer 9

Patellar tendon

Knee jerk reflex

Question 10

What is the simplest segmental reflex?

Answer 10

Stretch reflex

Question 11

What needs to contract and relax with the knee jerk reflex?

Answer 11

Contract the quadriceps

Relax the hamstrings

Question 12

Why do pathways occur in the knee jerk reflex?

Answer 12

Because one is needed to contract the quadriceps

And the other is needed to relax the hamstrings

Question 13

Which level is the biceps jerk?

Answer 13

C6

Question 14

Which level is the triceps jerk?

Answer 14

C7

Question 15

Which level is the patellar tendon reflex?

Answer 15

L4

Question 16

What level is the achilles tendon reflex?

Answer 16

S1

Question 17

Where are proximal shoulder muscles mapped to?

Answer 17

Medial motoneurones

Question 18

Where are distal muscles mapped to?

Answer 18

Lateral motoneurones

Question 19

What happens if there is damage to sensory inputs?

Answer 19

Paralysis as if the motoneurons themselves have been damaged

Question 20

What is the significance of reflex testing?

Answer 20

Can help to detect spinal cord damage

Can evoke reflexes above but not below the level of damage

Question 21

Why must patients be distracted during reflex testing?

Answer 21

To avoid voluntary influencing of response

Question 22

What are the steps of the pain reflex?

Answer 22

Increased sensory AP from pain receptors cause
Increased activity in the flexor muscle
Antagonists extensors are inhibited

Question 23

What happens to the contralateral limb in the pain reflex?

Answer 23

Increased activity in extensors
Decreased activity in flexors
Opposite to the other limb

Question 24

Why is the contralateral limb extended in pain reflex?

Answer 24

Protective mechanism to protect falling over

Question 25

Through which tracts does sensory information ascend to the brain?

Answer 25

In the spinothalmic tract

Question 26

What is babinskis sign a sign of clinically?

Answer 26

The Babinski sign can indicate upper motor neuron lesion constituting damage to the corticospinal tract.

Question 27

Why is the flexors crossed extensor reflex slower than the stretch reflex?

Answer 27

Because nociceptive sensory fibres have smaller diameter than muscle spindle fibre and so conduct more slowly

Question 28

How are reflexes overidden?

Answer 28

Descending voluntary excitation of alpha motoneurones can override the inhibition from the GTO's and maintain contraction

Question 29

What is the normal response when stroking the lateral aspect of the foot?

Answer 29

Causes plantar flexion (downwards curling of the big toe)

Question 30

When does the foot reflex only work?

Answer 30

If the Corticospinal tract is intact

Question 31

What does damage to the CST cause in the foot reflex?

Answer 31

Causes extension and not flexion so toes fan up and out

Question 32

Why is babinski sign seen in children?

Answer 32

Because their motor system is not fully developed

Question 33

What is there a loss of in spinal shock?

Answer 33

Supraspinal excitation

Question 34

How long does it take for the gradual return of reflexes in spinal shock?

Answer 34

2-6 weeks