Diseases of Skeletal Muscle and Peripheral Nerve

Question 1

Type I

Answer 1

red, slow myosin, endurance, rich in mito

Question 2

Type II

Answer 2

white, fast myosin, strength and speed, rich in glycolytic enzymes and glycogen

Question 3

Characteristics of muscle histo

Answer 3

polygonal myofiber outlines, peripheral nuclei

CT: endomysium

Question 4

How is fiber type determined?

Answer 4

neuron type innervating

Question 5

Progression of chronic denervation

Answer 5

1. normal
2. motor unit loss with small group atrophy
3. near neuron takes on denervated cells, change to all one type, is weaker than normal
4. if degenerative, remaining neuron will lose function –> large group atrophy

Question 6

What does neurogenic early denervation unit lead to?

Answer 6

• loss of motor unit –>
  1. small angular fivers
  2. involvement of both fiber types

Question 7

What does neurogenic chronic denervation lead to?

Answer 7

• Axonal sprouting and reinnervation –>
  1. large motor units
  2. fiber type grouping

Question 8

What does neurogenic late denervation lead to?

Answer 8

• loss of large motor unit –>

1. grouped atrophy

Question 9

Myasthenia Gravis

Answer 9

Neuromuscular Junction Problem, AB against ACh receptor on post-synaptic membrane

Question 10

Symptoms of Myasthenia Gravis

Answer 10

• lose strength throughout the day due to depletion of ACh

- can’t keep eyelids open

Question 11

What are general Myopathic changes?

Answer 11

• myofiber dgn, or regeneration
• internalization of nuclei
• increased endomysial CT (scar)
• inflammation
• vacuolation

Question 12

What are common inherited myopathies?

Answer 12

• Duchenne’s and Becker, X-linked

- Channelopathies, metabolic myopathic, mitochondrial

Question 13

What causes ragged red fiber?

Answer 13

compensatory proliferatino of mitochondria

Question 14

What is Type II atrophy seen with?

Answer 14

disuse, chronic disease, cachexia, corticosteroids

Question 15

What are 3 Inflammatory Myopathies?

Answer 15

polymyositis, dermatomyositis, inclusion body myositis

Question 16

Polymyositis pathology

Answer 16

intrafascicular inflammation

Question 17

dermatomyositis pathology

Answer 17

extrafascicular inflammation and perifascicular atrophy- mostly in perimysium (CT around fascicle)

Question 18

Polymyositis pathogenesis

Answer 18

CTL

Question 19

polymositis clincal

Answer 19

pain

Question 20

dermatomyositis pathogenesis

Answer 20

humoral

Question 21

dermatomyositis clinical

Answer 21

muscle pain and skin rash

Gottron’s papules: over MCP and IP joints

Question 22

inclusion body myositis pathology

Answer 22

inclusions; rimmed vacuoles

Question 23

Inclusion body myositis pathogenesis and clinical

Answer 23

DGN and steroid resistance

Question 24

Duchenne MD

Answer 24

dystrophin deficiency, X-linked, onset age 5-6

Question 25

Myotonic Dystrophy

Answer 25

trinucleotide repeat disorder

Question 26

Histological appearance of congenital myopathies

Answer 26

central core, rod body, centronuclear