Musculoskeletal

Question 1

What makes up a motor unit?

Answer 1

Single motor neuron and muscle fibres innervated by it

Question 2

What makes up a motor neurone pool?

Answer 2

All motor neurones that supply one whole muscle

Question 3

What is the neurotransmitter and receptor always found at a neuromuscular junction?

Answer 3

Acetylcholine

Nicotinic receptors

Question 4

What is the sarcolemma of a muscle fibre?

Answer 4

The muscle fibre membrane

Question 5

What part of the muscle fibre releases calcium on stimulation?

Answer 5

Sarcoplasmic reticulum

Question 6

What are T tubules of the muscle fibre and what do they allow?

Answer 6

Deep invaginations of sarcolemma

Allow for quick depolarisation of interior

Question 7

What causes depolarisation at the neuromuscular junction?

Answer 7

Influx of Na+

Question 8

What are the thick filaments of the muscle fibre also called?

Answer 8

Myosin

Question 9

What are the thin filaments of the muscle fibre also called?

Answer 9

Actin

Question 10

What happens to myosin when the muscle fibre is contracting?

Answer 10

Binds with actin and uses ATP to ‘recock’ heads

Question 11

What does tropomyosin do when not stimulated?

Answer 11

Lies over the actin filaments and blocks the myosin binding sites

Question 12

What does troponin do when it is activated?

Answer 12

Binds to calcium, causing a change in shape so that it pulls tropomyosin out of the way

Question 13

Which are the A bands and what happens to them during contraction?

Answer 13

The dark bands (myosin)

Stay at constant length

Question 14

Which are the I bands and what happens to them during contraction?

Answer 14

The light bands (actin)

Shorten during contraction

Question 15

What are the four ATP sources in skeletal muscle?

Answer 15

Phosphocreatine
Anaerobic respiration
Aerobic respiration
Free fatty acid oxidation

Question 16

What are the three types of muscle contraction and briefly describe each.

Answer 16

Isotonic - shortening
Isometric - remains same length
Eccentric - lengthening

Question 17

What type of muscle fibre is type I?

Answer 17

Slow twitch, oxidative fibre

Red in colour

Question 18

What type of muscle fibre is type IIa?

Answer 18

Fast twitch, oxidative fibre

Red in colour

Question 19

What type of muscle fibre is type IIb?

Answer 19

Fast twitch, glycolytic fibre

White in colour

Question 20

Which muscle fibre is most resistant to fatigue and which fatigues most rapidly?

Answer 20

Most resistant - type I

Fatigues rapidly - type IIb

Question 21

What is the red colour of muscle fibres due to?

Answer 21

High content of myosin

Question 22

What is the recruitment order of muscle fibres types?

Answer 22

1st - type I (smallest neurons - depolarise quicker)
2nd - type IIa
3rd - type IIb

Question 23

What does contraction strength depend on?

Answer 23

Number of motor units recruited

Frequency of impulses

Question 24

What is the difference in cartilage in the young, adults and elderly?

Answer 24

Young - hypercellular, no zones, no tidemark
Adult - hypocellular, high matrix, tidemark
Elderly - even fewer cells, matrix degradation

Question 25

What are responsible for degradation of cartilage?

Answer 25

Matrix metalloproteinases

Question 26

What type of collagen is articular cartilage primarily made of?

Answer 26

Type II

Question 27

What is the major proteoglycan of articular cartilage?

Answer 27

Aggrecan

Question 28

What type of collagen is primarily found in bone?

Answer 28

Type I

Question 29

What causes osteogenesis imperfecta?

Answer 29

Mutation in DNA coding for collagen type I

Question 30

What are the three development stages of bone matrix development?

Answer 30

Osteoid Woven bone Lamellar bone

Question 31

What happens in the osteoid stage of bone matrix development?

Answer 31

There is a collagen meshwork without mineralisation | Collagen is secreted by osteoblasts

Question 32

What happens in the woven bone stage of bone matrix development?

Answer 32

Bone is produced quickly, occurs in new bone formation or repair Randomly organised collagen fibres Mechanically weak

Question 33

What happens in the lamellar bone stage of bone matrix development?

Answer 33

End-stage, well organised and strong bone | Collagen organised in lamellae

Question 34

Describe compact (cortical) bone.

Answer 34

Solid, hard and dense Forms outer layer of most bone Is protective

Question 35

Describe spongy (trabecular/cancellous) bone.

Answer 35

Network of thin trabeculae separated by marrow space | Remodels in response to stress and mineral homeostasis

Question 36

What is the most common type of shoulder dislocation?

Answer 36

Anterior

Question 37

What is the treatment for shoulder dislocation?

Answer 37

Manipulation/surgery Painkillers Sling

Question 38

What sign would a torn rotator cuff show?

Answer 38

Loss of initial elevation of arm

Question 39

What is frozen shoulder and how would it present?

Answer 39

Adhesive capsulitis | Complete immobile shoulder

Question 40

What is a Bankart lesion?

Answer 40

Anterior part of labrum separated from glenoid, so anterior gleaned bare and more likely to dislocate at again

Question 41

What is a Hill-Sachs lesion?

Answer 41

A dent in the posterosuperior humeral head due to impact against the anteroinferior gleaned during dislocation Change in shape makes more likely to dislocate again

Question 42

What signs are seen on X-ray in osteoarthritis?

Answer 42

Reduced joint space Osteophytes Subchondral stenosis

Question 43

What are the two phases of the gait cycle and what percentage of the full cycle do they make up?

Answer 43

``` Stance phase (60%) Swing phase (40%) ```