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Flashcards in Movement pathways and centre Deck (54)
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1

What are lower motor neurons (LMNs) ?

neurons that originate from the brain stem and spinal cord

2

What are the components to the lower motor neuron (LMN)?

1. spinal nerve
2. ventral root
3. dorsal root ganglion
4. dorsal root
5. dorsal grey horn
6. ventral grey horn

3

What are lower motor neuron lesions due to?

1. peripheral nerve injury - crush or poliomyelitis
2. poliomyelitis

4

What do lower motor neuron lesions lead to?

1. muscle wasting
2. muscle weakness/ reduced power
3. hypotonia
4. absent tendon reflexes
5. fasciculations/ fibrillation

5

What are fasiculations?

small uncontrollable localised contractions

6

What is an example of a descending mortor pathway?

upper motor neurons (UMNs)

7

What 2 types of descending motor pathways are there?

1. corticospinal - cortex to spine - spinal nerves
2. corticobulbar - cortex to brainstem - cranial nerves

8

What does the descending motor pathways/ upper motor neurons do?

1. influence LMN activity
2. modify local reflex activity
3. superimpose more complex patterns of movement

9

How many important descending pathways are there and what are they named after?

4

named after origin

10

What is the typical route for descending patwhays/ upper motor neurons?

1. cerebral cortex
2. precentral gyrus
3. internal capsule
4. brainstem/spinal cord

11

Do all descending pathways work separately or together?

together

12

What are the descending pathways often referred to as?

pyramidal system

13

What happens initially if there is damage to the corticospinal tract only?

1. flaccid paralysis of opposite limbs
2. loss of tendon reflexes

14

What happens after several days to a week if there is damage in the corticospinal tract only?

1. motor function recovers

2. but there is hypertonia

15

What happens in the long term if there is damage to the corticospinal tract?

1. spasticity
2. hyperreflexia - increased reflexes
3. left with pernamanet inability to carry out fine movements of hands and feet

16

What do other pathways seem to do if there is damage to the corticospinal tract only?

appear to take over most corticospinal functions

17

What type of homunculus do you have?

1. somatosensory
2. motor homunculus

18

Where is the somatosensory homunculus?

in the post-central gyrus

19

Where is the motor homunculus?

in the pre-central gyrus

20

What is the order of the motor homunculus in the pre-cnetral gyrus medial to lateral?

1. knee
2. hip
3. trunk
4. shoulder
5. arm
6. elbow
7. wrist
8. hand
9. fingers
10. thumb
11. neck
12. brow
13. eye
14. face
15. jaw
16. tongue
17. pharynx
18. larynx

21

What is the order of the somatosensory homunculus in the post-central gyrus medial to lateral?

1. leg
2. hip
3. trunk
4. arm
5. elbow
6. forearm
7. hand
8. fingers
9. thumb
10. eye
11. nose
12. face
13. lips
14. teeth
15. gums
16. jaw
17. tongue
18. pharynx
19. abdomen

22

Where does the descending pathway (descending corticospinal/bulbar fibres) or upper motor neuron travel?

1. from pre central gyrus to internal capsule

23

What is the internal capsule?

deep bundle of white matter between the deep nuclei

24

What is the structure of the internal capsule?

1. anterior limb of internal capsule
2. lower limb of internal capsule
3. genu

25

Where do descending fibres for the body go?

posterior limb of the internal capsule

26

Where do descending fibres fro the face and muscles of the head go?

genu

27

What is the structure of the brainstem?

1. cerebral peduncle
2. basal pons
3. pyramids
4. olives

midbrain
pons
medulla

28

How does the descending pathway travel from internal capsule to spinal cord?

in the brainstem from cerebral peducnle to basal pons to pyramids and to contralateral spinal cord

29

How does the corticospinal pathway travel from cortex to spinal cord?

1. pre-central gyrus in cortex
2. inetrnal capsule
3. basis peduncles
4. pyramid
5. pyramidal decusstaion
6. lateral corticospinal tract

30

In terms of the decussation of pyramids what percentage of fibres cross and enter the lateral corticospinal tract?

85% fibres cross