Control of Motor Function

Question 1

Define cortical initiation of motion

Answer 1

regulation of complex movements; rhythmic movements & central pattern generators

Question 2

What are the direct activation (voluntary) pathways?

Answer 2

Corticospinal tract for non-head & corticobulbar pathway for head

Question 3

Describe the corticospinal tract. Where do the axons decussate?

Answer 3

• for non-head
• (UMN) motor cortex (medial) → (LMN) spinal cord ventral horn
• decussate in the medulla at the pyramids

Question 4

Define myotomse

Answer 4

areas of muscle are innervated by a particular spinal nerve root in a pattern analogous to sensory innervation in dermatomes. Thus, motor innervation maps to the motor homunculus in the cortex

Question 5

Motor neurons innervate in ___ for head or ___ for non-head & go out through spinal nerves to appropriate myotomes

Answer 5

brainstem
spinal cord ventral motor neurons

Question 6

Most of your motor control is in your

Answer 6

Hands

Question 7

Describe the corticobulbar pathway

Answer 7

• for head
• Each side of the motor cortex innervates the motor nuclei on BOTH sides of the midline
• (UMN) motor cortex (lateral) → (LMN) brain stem, cranial nerve, motor nuclei

Question 8

Face above eyebrows is ___ innervated; eyebrows & below are only___ innervated

Answer 8

bilaterally
contralaterally

Question 9

What is the indirect activation (involuntary) pathway?

Answer 9

Extrapyramidal tract (nonhead)

Question 10

Describe the extrapyramidal tract

Answer 10

• involved w/ posture & balance
• Upper motor neurons are in brainstem
• Axons travel down ipsilateral medial white matter on ventral side of spinal cord to innervate ventral lower motor neurons bilaterally

Question 11

___ pathway can override the ___ pathway

Answer 11

direct activation
indirect

Question 12

___ coordinates order of muscle contraction

Answer 12

Basal ganglia

Question 13

5 Basal ganglia we need to remember

Answer 13

Caudate nucleus
Putamen
Globus pallidus
Amygdala
Substantia nigra

Question 14

The subcortical nuclei of the basal ganglia are in

Answer 14

forebrain (deep cerebrum) & midbrain

Question 15

___ controls timing of contractions as the motor act is executed to coordinate muscles across multiple joints: fine motor control in response to sensory input

Answer 15

Cerebellum

Question 16

The cerebellum uses sensory input to modify movements according to ___

Answer 16

environment

Question 17

The cerebellum acts in response to

Answer 17

Proprioceptive input

Question 18

Define central pattern generators

Answer 18

Neural connections in local CNS that control fictive (rhythmic) movements w/o conscious command
- also called “black box” of neurons

Question 19

___ can override reflex & say to stop chewing

Answer 19

Cortex

Question 20

For walking, ___ & ___ input from the ground modifies stepping direction, speed & force

Answer 20

proprioceptive & mechanoreceptive

Question 21

2 examples of central pattern generators. Where is there CPG located?

Answer 21

• Chewing cycle - CPG in brainstem at the Obex
• Walking - CPG in the spinal cord

Question 22

Trauma to ___ or their axons causes loss of function

Answer 22

motor neurons

Question 23

What happens if you have an upper motor neuron lesion?

Answer 23

• Spastic paralysis
• Moderate muscle atrophy
• exaggerated reflexes

Question 24

What happens if you have a lower motor neuron lesion?

Answer 24

• Flaccid paralysis
• No movement (reflex or voluntary)

Question 25

Position of a lesion within a tract determines

Answer 25

which side of the body will be affected

Question 26

What is multiple sclerosis caused by? What happens? Can it be healed?

Answer 26

- Caused by autoimmune destruction of CNS myelin - Starts w/ motor function loss, both corticospinal & extrapyramidal - Somatosensory & autonomic involvement w/ progression - Can't be healed

Question 27

What is amyotrophic lateral sclerosis (Lou Gehrig's Disease)? Death is caused by what? ___% of cases are hertiable?

Answer 27

- Progressive upper & lower motor neuron degeneration in brain & spinal cord - Loss of voluntary control, progressing to loss of autonomic motor control - Death usually from respiratory failure - Mostly sporadic, but 5-10% of cases are heritable

Question 28

What causes parkinson's disease? What does it result in?

Answer 28

- Degeneration of dopaminergic neurons in the substantia nigra - Loss of motor function, characterized by tremors at rest

Question 29

What does cerebellar ataxia result in? What are deficits caused by?

Answer 29

- Loss of coordination in movements (Loss of balance, coordination of eye & arm movements) - "zombie walk" - Intention tremors - Deficits caused by a lesion are ipsilateral to site of lesion

Question 30

What is Huntington's Chorea caused by? What does it result in?

Answer 30

- Caused by mutations in HTT gene (autosomal dominant inheritance) - Characterized by uncoordinated, jerky movements & spasms, often involuntary & appearing as restlessness

Question 31

What is Tardive Dyskensia caused by? What does it result in?

Answer 31

- Caused by certain antipsychotic medications - Characterized by repetitive, involuntary movements, especially the face (Ex: tongue movements, eye blinking)

Question 32

Function of frontal lobe

Answer 32

Execute functions, thinking, planning, organizing, & problem solving, emotions & behavioral control, personality

Question 33

Function of motor cortex

Answer 33

Movement - Brodmann area 4

Question 34

Function of sensory cortex

Answer 34

Sensation

Question 35

Function of parietal lobe

Answer 35

Perception, making sense of the world, arithmetic, spelling

Question 36

Function of occipital lobe

Answer 36

Vision

Question 37

The primary motor cortex contains UMNs or LMNs for voluntary or involuntary movements

Answer 37

UMNs for voluntary movements

Question 38

The brainstem in the CNS contains UMN for involuntary movements & LMN for head or non head voluntary movements

Answer 38

Head

Question 39

The spinal cord contains UMNs or LMNs for head or non-head

Answer 39

LMNs for non-head

Question 40

Which cranial nerve is the only one that doesn't decussate?

Answer 40

CN XI

Question 41

Function of the temporal lobe

Answer 41

Memory, understanding, & language