The Motor system

Question 1

Motor control involves a dynamically changing mix of c____ and u____ regulation of muscle force, informed by continuous and complex s____ feedback, operating in a framework sculpted by e_____ p______.

Answer 1

conscious
unconscious
sensory
evolutionary
pressures

Question 2

Types of motor control

Answer 2

Voluntary
Goal-directed
Habit
Involuntary

Question 3

Which part of CNS responds to pain?

Answer 3

Spinal cord

Question 4

Which part of CNS responds to loom?

Answer 4

Sensorimotor midbrain

Question 5

Which part of CNS responds to a learned threat?

Answer 5

Cortex + Limbic system

Question 6

Sensorimotor system

Answer 6

motor control governed by UMNs and LMNs

LMN begins in spinal cord/ brainstem and projects to muscle

UMN originates in higher centres and project to LMNs

Question 7

Top down processing

Answer 7

A descending control system but with lots of ascending feedback

Question 8

Individual muscle fibres act in an ‘a__-o_-n___’ manner, and so control of muscle f___ depends on the way in which l___ motor neurons activate different types of muscle f___.

Answer 8

all-or-none
force
lower
fibre

Question 9

Muscles

Answer 9

activation of muscle fibres is all or none

Antagonistic arrangement - combined co-ordinated action

Recruitment of muscle fibres - fast /slow twitch, small and large motor units.

Question 10

Muscle size is about

Answer 10

Cross sectional area of individual fibres and different proportions of the different types of fibre

Question 11

Tendons

Answer 11

Attach skeletal muscle to bone

Question 12

Skeletal muscle comprises of

Answer 12

several muscle fasciculi (group of muscle fibres)

Question 13

A muscle fibre consists of several…

Answer 13

myofibrils

Question 14

Myofibrils contain the protein filaments…

Answer 14

actin and myosin

(when fibre is depolarised, slide against each other to produce contraction)

Question 15

What neurotransmitter triggers the biochemical cascade in muscle cells for contraction?

Answer 15

Acetylcholine for the myosin cross-bridge cycle

Question 16

ATP is needed to break bond between

Answer 16

myosin head and acting filmanent

Question 17

ATP is produced by

Answer 17

oxidative metabolism

Question 18

A motor unit consists of

Answer 18

One alpha motor neuron and and the muscle fibres it innervates (all of the same type)

Question 19

What is the result of more motor unit firing?

Answer 19

More power due to more fibres contracting

Question 20

Training and exercise lead to changes in the ___ of muscle fibres and the ___ of different muscle fibre types

Answer 20

Thickness
Proportion

Question 21

The Motor pool

Answer 21

All the LMNs that innervate a single muscle

Contains both alpha and gamma motor neurons

Often arranged in rod like shape within ventral horn of spinal column

Question 22

Cell bodies in ventral horn activated by

Answer 22

sensory information from muscle
Descending info from brain

Question 23

2 things the CNS need to know to provide good control of movement

Answer 23

How much tension is on the muscle
What the length (stretch) is of the muscle

Question 24

What can sense the tension within muscles?

Answer 24

Golgi tendon organs (GTO)

Within the tendon (muscle join to bone) and sends ascending sensory info to brain

Critical for proprioception

Question 25

What can sense the stretch of muscles?

Answer 25

Muscle spindles

Question 26

Extrafusal muscle fibres

Answer 26

Provide force

Question 27

Intrafusal muscle fibres

Answer 27

Sensory device to detect stretch length

Innervated separately by gamma motor neurons. Keep intrafusal fibres set at length which optimises muscle stretch detection