Diseases of muscle

Question 1

Muscle fibre components

Answer 1

Basal lamina, plasma membrane, mitochondria, sarcoplasmic reticulum, myofibrils, myonuclei

Question 2

Functional systems

Answer 2

Ion fluxes, neuromuscular transmission, excitation-contraction coupling, oxidative phosphorylation, mRNA transport

Question 3

Muscle disease symptoms

Answer 3

(Limited) Wasting, pain, cramping, fasciculations, weakness

Question 4

Clinical investigations

Answer 4

Clinical, electromyograph, nerve conduction studies, MRI, serum/blood investigations

Question 5

Biological basis

Answer 5

Nerves, motor end plates primary (myopathies - destructive and non-destructive)

Question 6

Classification

Answer 6

1. Diseases of the Sarcolemma & Extracellular Matrix
2. Diseases of Myonuclear Abnormalities
3. Diseases of Myofibrillar & Internal Cytoskeletal Proteins
4. Diseases of Ion Channels (Channelopathies)
5. Myopathies based on complex molecular defects
6. Developmental diseases
7. Disorders of catabolic mechanisms
8. Defects of neuromuscular transmission
9. Metabolic defects
10. Dysimmune & infectious myopathies
11. Toxins & Iatrogenic disorders
12. Chronic denervation
13. Endocrine disorders

Question 7

Sites for biopsy

Answer 7

Frontalis, pectorales, quadriceps, biceps, tibialis anterior, deltoid

Question 8

Where is most commonly biopsy?

Answer 8

Quadriceps - accessible and not traumatic

Question 9

Muscle biopsy

Answer 9

Snap frozen - mitochondrial enzymes

Frozen - routine histochemistry and IHC, stored/referred

Glutaraldehyde - EM

Formalin - Morphology and IHC

Question 10

Sarcolemma

Answer 10

The basal lamina