Muscle In Health And Disease

Question 1

What happens when potassium is low in muscles

Answer 1

Muscle Cramps

Question 2

Is skeletal under UMN or LMN control

Answer 2

LMN

Question 3

Where are LMNs found

Answer 3

Ventral horn of spinal cord
Cranial nerve nuclei

Question 4

Motor unit

Answer 4

motor neuron and all of the skeletal muscle fibers innervated by the neuron’s axon terminals

Question 5

What happens to a muscle fibre when it loses innervation

Answer 5

Atrophies and becomes angulated

Question 6

How are deinnervated muscle fibres reinnervated

Answer 6

Axons sprout from other motor neurones to innervate more fibres

Question 7

Target fibre

Answer 7

Re innervated muscle fibre that looks like a target due to central nuclei

Question 8

What determines whypich type of fibre a muscle fibre is

Answer 8

Primary motor neurone

Question 9

Why can muscle fibres switch between fast and slow when they are deinnervated and reinnervated

Answer 9

Fibre type determined by mtooor neurone

Question 10

Group atrophy

Answer 10

All fibres in a motor unit degenerate

Question 11

Muscle structure in infantile hypotonia

Answer 11

Most fibres small and round with a few massively hypertrophic fibres

Question 12

By what age are all symptoms of infantile hypotonia usually gone by

Answer 12

2 yrs

Question 13

2 forms of infantile hypotonia

Answer 13

Large type 1 fibres + small type 2 fibres
Small type 1 fibres + normal/large type 2 fibres

Question 14

Infantile hypotonia

Answer 14

abnormal limpness when an infant is born, affecting limbs, trunk, and head

Question 15

Sarcopenia/cachexia

Answer 15

Age related gradual loss of muscle mass, strength and function

Question 16

Are type 1 or type 2 muscle fibres more effected by sarcopenia

Answer 16

Type 2

Question 17

Why does sarcopenia not cause decrease in body part size

Answer 17

Muscle replaced by fat

Question 18

What causes muscle loss in sarcopenia

Answer 18

Pro inflammatory cytokines

Question 19

General muscle disorder symptoms

Answer 19

Pain
Weakness
Twitching
Cramps
Muscle atrophy
Contractures
Drug exposure
Endocrine disorders

Question 20

How can muscle disorders be diagnosed

Answer 20

Biopsy
EMG

Question 21

Difference between polymyositis and dermatomyositis

Answer 21

Same condition but pt has skin rash in dermatomyositis

Question 22

Polymyositis/dermatomyositis

Answer 22

Inflammatory myopathy causing chronic muscle inflammation, weakness, and pain (+ rash in dermatomyositis) from lymphocytes infiltrating CT around muscle fibres

Question 23

What type of disease are inflammatory myopathies

Answer 23

Autoimmune

Question 24

Rash characteristics in dermatomyositis

Answer 24

Red/purple
spotty/streaky
Hyperpigmentation in photodistribution pattern
Heliotrope rash over eyelids
Periorbital oedema
Hyperkeratotic papules on hands

Question 25

Is myosotis symmetrical

Answer 25

Yes

Question 26

How does myosotis effect serum creatine kinase

Answer 26

Incr

Question 27

EMG in myositis

Answer 27

Irritable

Question 28

Biopsy in myositis

Answer 28

Variation in fibre size Central nuclei Necrosis and regeneration Infiltration of inflam cells

Question 29

Hyperkeratotic papules

Answer 29

Epidermis thickens and keratinises Dermatomyositis

Question 30

Subcutaneous calcifications

Answer 30

Calcification in muscle and skin caused by autoimmune CT disease

Question 31

First step of subcutaneous calcification

Answer 31

Mucin deposition

Question 32

Myositis treatment

Answer 32

High dose corticosteroids Azathioprine Methotrexate Rituximab

Question 33

Most common muscle disease in elderly

Answer 33

Inclusion body myositis

Question 34

Inclusion body myositis signs and symptoms

Answer 34

slowly progressive weakness and wasting of muscles Associated polyneuropathy Loss of quadriceps reflex Dysphagia

Question 35

Which muscle are most effected by inclusion body myositis

Answer 35

Finger and wrist flexors Knee extensors

Question 36

Why does inclusion body myositis cause loss of quadriceps reflex

Answer 36

Quadriceps atrophy

Question 37

Inclusion body myositis biopsy

Answer 37

Empty vacuoles in muscle fibres clumps of cellular material in fibres - beta amyloid, hyperphosphorylated TAU, apolipoprotein E

Question 38

How does inclusion body myositis cause muscle atrophy

Answer 38

Muscle can’t contract properly due to vacuoles and cellular material so rip selves apart

Question 39

Muscular dystrophies

Answer 39

Progressive genetically linked degenerative myopathies

Question 40

X linked muscular dystrophies

Answer 40

Duchenne MD Becker MD limb girdle MD emery-Dreyfus MD

Question 41

Autosomal recessive muscular dystrophies

Answer 41

Limb girdle MD emery dreifuss MD

Question 42

Autosomal dominant muscular dystrophies

Answer 42

Facioscapulohumeral MD limb girdle MD emery dreifuss MD oculopharyngeal MD

Question 43

Most common MD

Answer 43

duchenne MD

Question 44

Duchenne MD progression

Answer 44

Proximal muscle weakness in first 2 yrs Continuous slow decline Unable to walk by 7-12yrs Death in early 30s

Question 45

Difference between duchenne and Becker MDs

Answer 45

Duchenne has no dystrophin Becker has some dystrophin

Question 46

What causes duchenne and Becker MD

Answer 46

No/ lack of dystrophin

Question 47

What is the gower manoeuvre and What condition is it associated with

Answer 47

child gets on hands-and-knees then walks hands up legs to stand Duchenne MD

Question 48

Why is creatine kinase elevated in duchenne MD

Answer 48

Muscle fibres rip self apart and repair continuously

Question 49

Dystrophin

Answer 49

Protein between myofibres and sarcolemma that acts as a membrane stabilizer during muscle contraction to prevent contraction-induced damage

Question 50

Duchenne MD biopsy

Answer 50

Fibre size variability Endomysial fibrosis Degenerating muscle fibres undergoing myophagocytosis Thickened Perimetrium Increased fibrotic material and fat Atrophy and fibre death

Question 51

What are dead muscle fibres replaced with in duchenne MD

Answer 51

Fibrotic material Fat

Question 52

What drugs can induce myopathies

Answer 52

Corticosteroids Statins Alcohol Hydroxychloroquine

Question 53

Fibromyalgia

Answer 53

chronic disorder characterized by widespread pain and other symptoms such as fatigue, muscle stiffness, and insomnia

Question 54

Which antibodies are associated with fibromyalgia

Answer 54

Anti polymer antibodies

Question 55

How many of 18 specific points need to be tender when pressure applied for fibromyalgia diagnosis

Answer 55

11

Question 56

Fibromyalgia treatment

Answer 56

Tricyclic antidepressants - Amitryptyline SSRIs - fluoxetine Exercise Massage, therapy, yoga