Motor Systems l

Question 1

What function does the motor system have?

Answer 1

Functions to move the body

Question 2

What are the parts of the motor system? (6)

Answer 2

• Motor Cortex
  –Spinal Cord
  –Brainstem
  –Motor Nerves (CN &
  spinal)
  –Basal Ganglia
  –Cerebellum

Question 3

What is the function of the posterior motor cortex?

Answer 3

Provides sensory information to the frontal cortex

Question 4

What is the function of the prefrontal cortex?

Answer 4

Plans movements

Question 5

What is the function of the premotor cortex?

Answer 5

Organize movement sequences

Question 6

What is the function of the motor cortex?

Answer 6

Produces specific movements

Question 7

What is the order of the motor signal on the cortex? (4)

Answer 7

Question 8

How many homunculi do the primary motor and premotor cortices contain?

Answer 8

10 homunculi

Question 9

What do the disproportionate sizes of the homunculi represent?

Answer 9

The complexity of movements that they can perform

Question 10

Larger are in the homunculi = greater ____________

Answer 10

motor control

Question 11

Which parts of the homunculi are especially large?

Answer 11

Hand and Face

Question 12

What would happen if we would electrically stimulate a certain area in the motor cortex?

Answer 12

It would elicit movements of body parts corresponding to the map of the body

Question 13

Is the motor system responsible for:

a) Control of individual muscles
b) Specialized control of muscle combinations (movement)
c) Information processing of our sensory information

Answer 13

b) Specialized control of muscle combinations (movement)

Question 14

Different homunculi represent different classes of ____________ specified by ____________, __________________ and ___________.

Answer 14

movement
body part
movement location
function

Question 15

Different homunculi represent different classes of ____________ specified by ____________, __________________ and ___________.

Answer 15

movement
body part
movement location
function

Question 16

What are the two main motor pathways?

Answer 16

Direct Pathway
Indirect Pathway

Question 17

What is another name for the direct pathways in motor systems?

Answer 17

Pyramid Pathway

Question 18

What is another name for the indirect pathways in motor systems?

Answer 18

Extrapyramidal Pathway

Question 19

Where do Pyramidal neurons (upper motor neurons) originate from?

Answer 19

Motor cortex

Question 20

Upper motor neurons are part of which nervous system?

Answer 20

CNS

Question 21

Lower motor neurons are part of which nervous system?

Answer 21

PNS

Question 22

Pyramidal neurons (i.e., upper
motor neurons) originating in motor
cortex project directly to: (2)

Answer 22

–Brainstem as Corticobulbar tract
–Spinal cord as Corticospinal tract
(aka Pyramidal tract)

Question 23

The pyramidal neurons from the motor cortex projection to the brainstem is called the ___________________ tract

Answer 23

Corticobulbar Tract

Question 24

The pyramidal neurons projection to the Spinal is called the ___________________ tract

Answer 24

Corticospinal Tract

Question 25

The corticobulbar Tract Synapses on which cranial nerves (lower motor neurons)? (6)

Answer 25

CN 5 7 9 10 11 12

Question 26

Why does the corticobulbar tract synapse specifically with the CN 5 7 9 10 11 12?

Answer 26

Because they are motor nerves (or mixed) that control face, head and neck.

Question 27

Corticobulbar regulation of MOST cranial nerves is _________________

Answer 27

Bilateral

Question 28

Give an example of the fact that Corticobulbar regulation of most cranial nerves is bilateral.

Answer 28

E.g., fibers from left motor cx innervate left & right cranial nerve motor nuclei in brainstem

Question 29

What is the clinical implication of the fact that Corticobulbar regulation of most cranial nerves is bilateral?

Answer 29

Unilateral lesions to upper motor neurons have mild effects on motor control of speech, but bilateral lesions can cause severe dysarthria

Question 30

In the corticospinal tract, the primary motor cortex projects to the ___________

Answer 30

Spinal Cord

Question 31

____% of fibers from each hemisphere CROSS in brainstem (i.e., pyramidal decussation) and descend in the spinal cord as the LATERAL corticospinal tract

Answer 31

95%

Question 32

95% of fibers from each hemisphere cross in brainstem (i.e., pyramidal decussation) and descend in the spinal cord as the _____________________________

Answer 32

lateral corticospinal tract

Question 33

What is another name for the crossing of fibers in each hemispheres?

Answer 33

Decussation

Question 34

What does the lateral corticospinal tract control?

Answer 34

movements of limbs/digits

Question 35

____% of fibers from each hemisphere DO NOT CROSS in brainstem and descend in the spinal cord as the VENTRAL (or anterior) corticospinal tract

Answer 35

5%

Question 36

What is Dysarthria?

Answer 36

difficulty speaking caused by brain damage, which results in an inability to control the muscles used in speech.

Question 37

5% of fibers from each hemisphere do not cross in brainstem and descend in the spinal cord as the ________________________________________

Answer 37

ventral (or anterior) corticospinal tract

Question 38

What does the ventral (or anterior) corticospinal tract control?

Answer 38

Movements of trunk

Question 39

Where do corticospinal axons terminate?

Answer 39

On spinal cord motor nerves (i.e., lower motor neurons)

Question 40

_____________________ terminate on spinal cord motor nerves (i.e., lower motor neurons)

Answer 40

Corticospinal axons

Question 41

Where are the corticospinal axons located?

Answer 41

Located in the ventrolateral spinal cord and jut out to form the ventral horns

Question 42

Lateral corticospinal tract synapses with interneurons and motor neurons that innervate ________________________________.

Answer 42

muscles of the limbs and digits

Question 43

Interneurons project to__________________

Answer 43

Motor neurons

Question 44

Motor neurons project to ___________________________

Answer 44

muscles of the body

Question 45

Ventral corticospinal tract synapses with _____________________ and _______________ neurons that innervate the trunk

Answer 45

interneurons and motor neurons

Question 46

The interneurons and motor neurons of the spinal cord are envisioned as a ____________________ that representing the muscles that they innervate

Answer 46

homunculus

Question 47

Since the corticospinal tract is mostly crossed (i.e., contralateral), unilateral lesions to upper motor neurons affect limb movement ________________________________

Answer 47

on the opposite side of body

Question 48

What are clinical implications from unilateral lesions to upper motor neurons affect limb movement?

Answer 48

Since the corticospinal tract is mostly crossed (i.e., contralateral) it unilateral lesions can cause: Hemiplegia Hemiparesis

Question 49

What is hemiplegia?

Answer 49

one-sided paralysis

Question 50

What is hemiparesis?

Answer 50

weakness or the inability to move on one side of the body