Muscle Atrophy

Question 1

What are the causes of muscle atrophy?

Answer 1

Motor neuron disease (ALS), poliomyelitis, peripheral neuropathy, trauma, disuse (Type II fibers), glucocorticoids (Type II fibers), hypercortisolism

Question 2

What is disuse atrophy?

Answer 2

Muscle atrophy caused by immobilization, primarily affecting Type II fibers

Question 3

Which type of muscle fibers are affected by glucocorticoids?

Answer 3

Type II fibers

Question 4

Which type of muscle fibers are affected by disuse atrophy?

Answer 4

Type II fibers

Question 5

What is neurogenic group atrophy?

Answer 5

Muscular shrinkage due to deprivation of normal innervation

Question 6

Initially, how are muscle fibers affected in neurogenic group atrophy?

Answer 6

All muscle fibers of a motor neuron are affected

Question 7

What happens LATER in neurogenic group atrophy?

Answer 7

Collateral sprouting occurs; one surviving nerve takes over

Question 8

How does fiber type change in neurogenic group atrophy?

Answer 8

A single fiber type dominates, losing the normal Type 1 and Type 2 mixture

Question 9

What is the histological feature of neurogenic group atrophy?

Answer 9

Small, angulated muscle fibers