Motor Control #2 Flashcards Preview

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Flashcards in Motor Control #2 Deck (16):
1

what inputs into the MN

1) descending tracts
2) spinal interneurons (eg 1a inhibitory neurons)
3) Propriospinal neurons

2

THe three main receptors that control movement are

Muscle spindles ( change in length and speed of this change)
Golgi tendon organs
Nociceptive (pain) receptors on skin
(also joint receptors)

3

Why does the motor system control movement WITH sensory systems

We need to recieve signals coming BACK from muscles/ tendons /joints to give us info to the CNS on how the movement went.

4

Where else do we get info in for movements

Vestibular
retina
auditory
offactory
skin receptors

5

What are the three main reflexes?

Stretch
Reverse myotatic
flexion (withdrawal) reflex and cross extension

6

Why do we care about reflexes?

They indicate neurological disorders.

7

Five elements of spinal reflexes

receptors
afferent fibres
central synaptic relays
efferent motor fibres
effectors

8

What is the stretch reflex? How do we test?

evoked from stretch or vibration of muscle
and monosynaptic reflex (only one in body)
Hit quads tendon. this streches the muscle spindles and activates them in synchrony. AP induced in 1a afferents, evoke post-synaptic potential in alpha-MN, induce AP and muscle contraction occurs.

9

Components of stretch reflex

receptors= muscle spindles
afferent fibres= 1a afferents
central synaptic relays =synapses on a-MN
efferent motor fibres= alpha MN axons
effectors- extrafusal fibres

10

Whats reciprocal inhibition

Additonal synapses on 1a inhibitory interneurons, from 1a collateral afferents. these inhibit antagonist muscles. eg) when bicep contracts, triceps relaxes

11

What is Gamma-MN's role

to innervate the muscle spindle fibres (at the periphery) causing them to stretch. this means that during muscle contraction the spindles aren't 'unloaded' and info about the change of length is still being sent. when alpha-MN are activated there is an almost synchronised activation of gamma-MN

12

what are golgi tendon organs

receptors involved in the reverse myotactic reflex. can cause the muscle to lose tension during a muscular task, to protect the muscle from overloading. The 1b afferents synapse on 1b inhibitory interneurons, that hyperpolarize and inhibit the cell bodies of alpha-MN, so the muscle RELAXES. At the same time, the antagonistic muscles are activated

13

Where would you find golgi tendon organs?

In tendons of every muscle

14

Components of reverse myotactic reflex?

receptors= golgi tendon organs
afferent fibres= 1b afferents
central synaptic relays= 1b afferents to 1b inhibitory interneurons which inhibit alpha-MN
efferent motor fibres= axons of alpha-MN
effectors= muscles

15

Components of flexion withdrawal reflex

receptors= nociceptors
afferent fibres= type III and IV fibres
central synaptic relays= to excitatory interneurons which excite a MNs controling flexors
efferent motor fibres= axons of alpha-MN
effectors= flexor muscles

16

Are nociceptors fast or slow?

Relatively slow