Motor units, joint receptors, spinal reflexes and UMNs

Question 1

when muscles work together

Answer 1

synergists

Question 2

when muscles oppose each other

Answer 2

antagonists

Question 3

axial muscles control movements of?

Answer 3

trunk

Question 4

lower motor neurones control..?

Answer 4

contraction of muscles

Question 5

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

Answer 5

alpha and gamma

Question 6

where do LMNs leave the spinal cord?

Answer 6

in anterior roots

Question 7

what is a motor unit?

Answer 7

and alpha motor neurone and all the muscle fibres it innervates

Question 8

what is a motor neurone pool?

Answer 8

COLLECTION OF alpha motor neurones that innervate a single muscle

Question 9

what is the force of contraction graded by?

Answer 9

frequency of action potential discharge of alpha LMN

the recruitment of additional , synergistic motor units

Question 10

muscle strength depends on..?

Answer 10

neuromuscular activation

force produced by innervated muscle fibres (fibre size etc)

Question 11

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

Answer 11

extensors

Question 12

what causes muscle spindle to contract?

Answer 12

gamma LMNS

Question 13

what makes up the muscle spindle?

Answer 13

intrafusal fibres- nuclear bag fibres and chain fibres

Question 14

what innervates the muscle spindle?

Answer 14

la afferents- is around the centre of all of them

ll fibres- more slowly conducting flowerspray endings on all of them

Question 15

where are golgi tendon organs found?

Answer 15

between muscle and tendon

they monitor changes in muscle tension

innervated by lb sensory afferents

Question 16

where are proprioceptive axons found?

Answer 16

in connective tissue of joint

they respond to change in angle, direction and velocity

prevent excessive flexion or extension

Question 17

what do inhibitory interneurones mediate?

Answer 17

the inverse myotatic response

reciprocal inhibition between extensors and flexors

Question 18

what do excitatory interneurones mediate?

Answer 18

flexor reflex- causes limb to flex

crossed extensor relfex- caused limb to extend

Question 19

what are the 2 types motor pathways?

Answer 19

lateral and ventromedial

Question 20

what are the 2 types of lateral motor pathway?

Answer 20

corticospinal(main one)

rubrospinal (minor one)

Question 21

1. what pathway helps hold you upright and deals with balance and posture
2. and controls head and neck movement

Answer 21

ventromedial pathways

VESTIBULOSPINAL TRACTS

1. lateral
2. medial

Question 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

Answer 22

tectnospinal tract

Question 23

pontine (medial) RETICULOSPINAL TRACT

Answer 23

arise from brain stem and descend ispilaterally
enhances anti gravity reflexes

helps maintain a standing posture

Question 24

medullary (lateral) RETICULOSPINAL TRACT

Answer 24

arise from brainstem

descend bilaterally
opposes action of medial tract (pontine)