Motor units, joint receptors, spinal reflexes and UMNs Flashcards Preview

Neurology year 3 > Motor units, joint receptors, spinal reflexes and UMNs > Flashcards

Flashcards in Motor units, joint receptors, spinal reflexes and UMNs Deck (24):
1

when muscles work together

synergists

2

when muscles oppose each other

antagonists

3

axial muscles control movements of?

trunk

4

lower motor neurones control..?

contraction of muscles

5

lower motor neurones consists of 2 types of motor neurones..? which?

alpha and gamma

6

where do LMNs leave the spinal cord?

in anterior roots

7

what is a motor unit?

and alpha motor neurone and all the muscle fibres it innervates

8

what is a motor neurone pool?

COLLECTION OF alpha motor neurones that innervate a single muscle

9

what is the force of contraction graded by?

frequency of action potential discharge of alpha LMN

the recruitment of additional , synergistic motor units

10

muscle strength depends on..?

neuromuscular activation

force produced by innervated muscle fibres (fibre size etc)

11

monosynaptic reflex arc is most prominent in what type of muscle?

extensors

12

what causes muscle spindle to contract?

gamma LMNS

13

what makes up the muscle spindle?

intrafusal fibres- nuclear bag fibres and chain fibres

14

what innervates the muscle spindle?

la afferents- is around the centre of all of them
ll fibres- more slowly conducting flowerspray endings on all of them

15

where are golgi tendon organs found?

between muscle and tendon

they monitor changes in muscle tension

innervated by lb sensory afferents

16

where are proprioceptive axons found?

in connective tissue of joint


they respond to change in angle, direction and velocity

prevent excessive flexion or extension

17

what do inhibitory interneurones mediate?

the inverse myotatic response

reciprocal inhibition between extensors and flexors

18

what do excitatory interneurones mediate?

flexor reflex- causes limb to flex

crossed extensor relfex- caused limb to extend

19

what are the 2 types motor pathways?

lateral and ventromedial

20

what are the 2 types of lateral motor pathway?

corticospinal(main one)
rubrospinal (minor one)

21

1.what pathway helps hold you upright and deals with balance and posture

2.and controls head and neck movement

ventromedial pathways

VESTIBULOSPINAL TRACTS
1. lateral
2. medial

22

cell bodies reside in superior colliculus which gets input from retina and visual cortex

axons decussate in dorsal tegmental decussation and descend close to midline as the tectospinal tract

tectnospinal tract

23

pontine (medial) RETICULOSPINAL TRACT

arise from brain stem and descend ispilaterally
enhances anti gravity reflexes

helps maintain a standing posture

24

medullary (lateral) RETICULOSPINAL TRACT

arise from brainstem

descend bilaterally
opposes action of medial tract (pontine)