Lecture 7: Neuromuscular Aspects of Movement II

Question 1

CNS

Answer 1

Brain
Spinal cord

Question 2

PNS

Answer 2

Nerve branch pairs
- 12 cranial
- 31 spinal

Plexuses
- cervical, brachial, lumbar, sacral

Question 3

Afferent nerves

Answer 3

aka sensory nerves

carry information TO the CNS (Arrive)

Question 4

Efferent nerves

Answer 4

aka motor nerves

carry information FROM the CNS (Exit)

Question 5

Myotomes

Answer 5

Area of MUSCLE CONTROLLED by a specific nerve pair

Differ slightly btwn ppl

MOTOR NERVES leave the brain and spinal column in pairs

Question 6

Dermotomes

Answer 6

Area of body FELT by a specific nerve pair

SENSORY NERVES enter the brain and spinal column in pairs

Question 7

Motor cortex

Answer 7

Part of brain that DECIDES on which muscles to activate

Where commands come from when you want to MOVE

Question 8

Somatosensory cortex

Answer 8

Where FEELINGS from body parts (SENSORY) arrive for processing

Question 9

Motor Homunculus

Answer 9

Homonculus means “little man”

Shows parts of body controlled by motor cortex

Larger area = greater and finer control

HAND AND MOUTH (speech) dominate

Question 10

Motor unit

Answer 10

All muscle fibres activated by one motor nerve

For fine control, muscles have less motor units

Powerful muscles have many motor units

Question 11

EMG

Answer 11

Electromyography

The signal in the motor nerve is an AP

When the AP reaches the muscle, it is amplified and travels along the muscle from the NMJ

Question 12

Types of EMG

Answer 12

Surface EMG w/ skin mounted electrodes
- differential w/ 2 contacts

Fine wire EMG w/ wire electrodes inserted via a needle

Question 13

Surface EMG

Answer 13

Summation of 1000s of APs in muscle fibres
- multiple muscles can be tracked simultaneously to record sequencing of muscle activation

EMG: hissing sound (flexing against resistance)

Walking EMG: steam engine sound

• downside is having shaved patches

Question 14

Fine wire EMG

Answer 14

From APs of only 1 or 2 muscle fibres so it looks very different

• downside: Pt wire can break in body

Question 15

Basic muscle tone

Answer 15

amount of tension in muscles

muscles always contract slightly and make noise

Question 16

Muscle fibre types

Answer 16

• Type I
• Type IIa
• Type IIb

Question 17

Type I fibres

Answer 17

slow twitch, oxidative fibres

slow to contract but very fatigue resistant

Ex. soleus

Question 18

Type IIa fibres

Answer 18

fast twitch, oxidative fibres (lactic acid)

fast to contract but fatigue resistant

Ex. last 30m of 100m sprint

Question 19

Type IIb fibres

Answer 19

fast twitch, glycolytic fibres (use stored up glycogen in muscle)

fast to contract, fast to fatigue when glycogen runs out (builds lactic acid = pain)

Ex. sprints until about 70m of 100m

Question 20

Elastic storage of energy

Answer 20

When muscle-tendon structure is stretched, elastic energy is stored in tissue
- energy is released when the muscle shortens again (used to produce extra force)

Question 21

Stretch-shorten cycle

Answer 21

Use elastic storage

Ex. To jump straight high, you bend down first and stretch tendons which stores elastic energy

Ex. loading up structures when pitching

Question 22

Ascending limb of length-tension curve

Answer 22

Sarcomeres are too short = active insufficiency

Question 23

Descending limb of length-tension curve

Answer 23

Sarcomeres are too long = passive insufficiency
- helped by elastic tissue

Question 24

Elasticity and length-tension

Answer 24

Elastic component stretches out longer than contractile component
- more force when muscle goes into passive insufficiency

Less of a drop off in passive insufficiency during stretch-shortening cycle

Question 25

Muscle Power

Answer 25

Power = Force x Velocity

Question 26

Proprioception

Answer 26

Our ability to know what position each of our joints are in without having to look (Our ‘6th sense’)

Afferent (sensory) nerves take signals from muscles, tendons and jts back to brain in somatosensory cortex = gives us our sense of kinesthesis

Question 27

How is proprioception sensed?

Answer 27

• Golgi tendon organs
• Spindle fibres in the muscle
• Pressure sensors in the joint
• Cutaneous sensors in the skin

Question 28

How to increase proprioception?

Answer 28

With taping
- tape increases skin feeling but does not support biomechanical loading