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Flashcards in 5.1 Motor System Deck (61):
1

What are the three types of neurones in the sensory system?

First, second and third order

2

What are the two types of neurones in the motor system?

Upper and lower motor neurones

3

What type of motor neurone neurones are found the PNS?

Lower motor neurones

4

Where is the cell body of an UMN found?

In the CNS

5

Where is the axon of a UMN found?

In the CNS

6

Where is the cell body of a LMN found?

In the CNS

7

Where is the axon of a LMN found?

In the CNS

Projects along the peripheral nerves

8

What WILL happen if a lower motor neurone is activated?

Muscle movement

9

What is the target of a LMN?

Skeletal muscle

10

In which two places do LMNs reside?

Ventral horn of spinal cord

Brainstem nuclei

11

What resides in the occulomotor nuclei?

Cell bodies of LMN

Of the axons that travel in CN III

12

What is found in the nuclei in the brain?

Cell bodies

13

Which spinal nerves are involved in quadriceps contraction?

L3 L4

L4 L4 kick the door

14

Which spinal nerve is important in the contract of the hamstrings?

L5

15

Why does the hamstring not contract during the patella tendon reflex?

Branch off of sensory neurone synapses with inhibitory neurone

Inhibits the LMNs (in L5) which contract the hamstrings

16

What is the normal response of the Babinski reflex?

Big toe flexion

17

What would happen if you did the Babinski test on a baby?

the foot would extend

18

What are the signs of lower motor neurone damage?

Weakness
Areflexia
Muscle wasting
Fasciculation
Hypotonia

19

What is areflexia?

Absent deep tendon reflexes

20

Why do muscles waste if the lower motor neurone is damaged?

Because the LMN supplies the muscle with trophic factors

21

How long does it take for muscle wasting to begin to appear?

Weeks/months

22

What is fasciculation?

Uncoordinated muscle contractions

23

What is hypotonia?

Decreased muscle tone

Absent or low level contraction

24

Why does areflexia occur in LMN lesions?

Because the reflex arc is incomplete

25

Where are UMN cell bodies found?

Cerebral cortex

Brainstem

26

What two things do UMNs do to a LMN?

Excite them

Inhibit them via interneurons

27

What is the net effect of all UMN inputs on the LMNs?

Net inhibitory effect

28

Where do the cell bodies of LMNs reside?

Ventral horn of the spinal cord

29

What is the corona radiata?

White matter projections

ascending and descending projections

From cerebral cortex to internal capsule
(VICE VERSA)

30

As the projections within the corona radiata converge what structure is formed?

Internal capsule

31

What are the structures either side of the internal capsule?

Medially - Thalamus

Laterally - lentiform nucleus

32

What makes up the lentiform nucleus?

Globus pallidus

Putamen

33

Which way around are the putamen and the globes pallid us in the lentiform nucleus?

Larger, lateral structure = putamen

Smaller, medial structure = globes pallidus

34

Which vessels supply the internal capsule?

Lenticulostriate arteries

35

What do axons pass through as they leave the internal capsule?

Cerebral peduncle

36

Where do UMNs decussate?

Medullary pyramids

(Caudal end)

37

Within which structure do UMNs reside, after they have decussated?

Lateral corticospinal tract

38

Where does the lateral corticospinal tract reside?

Within the lateral funinculus

39

What kind of neurones does the lateral corticospinal tract contain?

UMNs

Which have ALREADY decussated

40

What does the facial motor nucleus contain?

LMN cell bodies

of axons supplying the facial muscles

41

How many projections do brainstem nuclei receive?

Two from each side

42

What is special about the facial motor nuclei?

Has an upper and lower half

Supplies upper and lower halves of face separately

43

How do the two halves of the facial motor nuclei continue as the axons leave?

Continue together as the facial nerve

44

How do cortical projections for the UPPER face supply the facial motor nunclei?

Sends brach to both nuclei

(to the respective halves of the nuclei)

45

How do cortical projections for the LOWER face supply the facial motor nuclei?

Only sends branch to the CONTRALATERAL nucleus

(To the respective half of the nucleus that supplies the lower part of the face)

46

What would a right facial motor nuclei lesion cause?

Left lower facial weakness

47

Why is the forehead spared and they can raise their eyebrows if a patient were to have a stroke affecting their face?

Because of the bilateral innervation of the upper half of the facial motor nuclei

48

What is interesting about the innervation of the cranial nerve motor nuclei?

They're almost all typically innervated bilaterally by the cerebral Cortex

49

If left sided cerebral cortex projections to the trigeminal nucleus were damaged, what would you expect to see?

Not much

The nuclei are BILATERALLY innervated

50

If you had a right sided stroke affecting the face, what signs would you see?

Left lower facial weakness

51

What are signs of an UMN lesion?

Weakness
Hypertonia
Hyperreflexia
Extensor plantar response

52

Why does hypertonia occur in UMN lesions?

Because the net inhibitory effect of UMNs on LMNs is removed

53

Why does hyperreflexia occur in UMN lesions?

Loss of inhibition from UMNs on LMNs

54

Why might a UMN lesion appear to be a LMN lesion initially?

Because signs of UMN lesion are often LATE signs

Spinal shock

55

Which type of motor neurones are involved with deep tendon reflexes?

LMNs

56

Why do primitive spinal reflexes that appear in babies, disappear over time?

Due to maturation of UMN pathways

57

Where are UMNs found in the cerebral cortex?

Primary motor cortex

(Pre-central gyrus)

58

What is the route of UMNs from the cortex?

Corona Radiata -->
Internal capsule -->
Cerebral peduncle -->
Pons -->
Medullary pyramids -->
Decussation of pyramids -->
Lateral corticospinal tract -->
Ventral horn/Brainstem nuclei -->
Synapse

59

What kind of motor movement is the lateral corticospinal tract involved in?

Fine motor control

60

What do UMNs that supply facial structures leave the pathway to create?

Corticobulbar tract

61

What does the corticobulbar tract do?

Innvervates LMNs in the cranial nerve motor nuclei