Systemic Path > MSK 4 > Flashcards

MSK 4 Flashcards

(72 cards)

Study These Flashcards
1
Q

What are the three main types of muscle?

A
  1. Skeletal (striated, voluntary, ex. muscles attached to skeleton)
  2. Cardiac (striated, involuntary, ex. myocardium)
  3. Smooth (Not striated, involuntary, ex. blood vessels and GI viscera)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a myofiber?

A

A tubular muscle cell (also called a muscle fiber)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the plasma membrane of a muscle cell called?

A

Sarcolemma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the cytoplasm of a muscle cell called?

A

Sarcoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the nucleus of skeletal muscle fibers.

A

They are multinucleated and located in the periphery of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True or False: Skeletal muscle cells have terminal differentiation.

A

True. Skeletal muscle cells cannot divide to replace injured/damaged cells because they are not mitotically active.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are satellite cells?

A

Mitotically active skeletal muscle precursor cells (called myoblasts).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

True or False: Satellite cells have terminal differentiation.

A

False. They are capable of dividing and reforming myofibers (muscle regeneration).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are muscle types determined by?

A

The activity of the innervating motor neuron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a motor unit?

A

A muscle fiber(s) + an innervating motor neuron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

True or False: In a motor unit, there is simultaneous contraction of all muscle fibers.

A

True. All muscle cells innervated by the same motor neuron will contract at the same time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does pale muscle look like grossly?

A

It is pink or white and usually indicates necrosis with or without mineralization.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is muscle atrophy?

A

A reversible reduction in muscle volume or mass.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do you see microscopically with muscle atrophy?

A

Decreased size (diameter) of muscle fibers rather than loss of muscle fibers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the four common causes of muscle atrophy?

A
  1. Denervation
  2. Disuse
  3. Malnutrition/cachexia
  4. Endocrine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe denervation atrophy.

A
  • Characterized by rapid atrophy (muscle is half the size in a matter of weeks)
  • Long‐standing denervation may result in fibrosis & fat infiltration (steatosis) of affected muscles.
  • Type 1 & 2 myofibers affected
  • Also called neurogenic atrophy.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe disuse atrophy.

A
  • The innervation of the muscle is intact
  • Atrophy is due to immobilization of a limb or body part because of pain (fracture, tenotomy, ankylosis)
  • May also be caused by a primary muscle disease (myopathy)
  • Primarily affects type 2 myofibers.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe malnutrition or cachexia muscle atrophy.

A
  • Physical wasting due to malnutrition or associated with chronic disease or neoplasia
  • May have a normal appetite and nutrient intake (cachexia)
  • Occurs slowly over time
  • Type 2 myofibers primarily affected.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe endocrine muscle atrophy.

A
  • Examples include hypothyroidism and hyperadrenocorticism (Cushing’s disease).
  • Primarily affects type 2 myofibers.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is muscle hypertrophy?

A

Reversible increase in muscle volume or mass due to an increase in the size (diameter) of muscle fibers, but the number of muscle fibers (cells) do not increase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is muscle hyperplasia?

A

An increase in muscle volume or mass due to an increase in the number of muscle fibers with no change in size or structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is muscle necrosis? What is another name for it?

A

A common sequela of muscle fiber injury regardless of its cause.

Also called myonecrosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the two types of muscle necrosis?

A
  1. Segmental (Zenker’s degeneration): Death of a portion of a muscle fiber.
  2. Global: Death of entire muscle fiber.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a common histologic feature of muscle fiber necrosis?

A

Mineralization. Calcium is released when muscle cell dies, leading to mineralization.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What does the ability for muscle to regenerate depend on?
1. Preservation of satellite cells 2. Preservation of basal lamina 3. An adequate blood supply 4. Removal of necrotic debris.
26
If one or more of the muscle regeneration factors is missing, what replaces the necrotic muscle?
Fibrous tissue (scar).
27
What would you see on histology with a monophasic muscle injury?
The histologic changes are all of the same duration (suggests a single insult).
28
What would you see on histology with a polyphasic muscle injury?
The histologic changes are of variable duration (suggests ongoing muscle damage).
29
What are the four categories of muscle injury?
1. Focal monophasic muscle injury 2. Multifocal monophasic muscle injury 3. Focal polyphasic muscle injury 4. Multifocal polyphasic muscle injury.
30
What is congenital muscular hyperplasia? What is a common term for this?
When there is an increase in the number of muscle fibers (true hyperplasia), but the muscle fibers are of normal size. ## Footnote Also called 'double muscling' of cattle.
31
What is congenital muscular hyperplasia caused by?
A defect in the myostatin gene (this gene normally limits growth).
32
What is muscular dystrophy characterized by?
Ongoing myofiber necrosis and regeneration.
33
What is muscular dystrophy?
An inherited and progressive degenerative disease.
34
What classification of lesion does muscular dystrophy cause?
It causes multifocal polyphasic lesions.
35
What is muscular dystrophy caused by?
A defect in the dystrophin gene.
36
What is myotonia?
A temporary inability of skeletal muscle fibers to relax (muscle stiffness/prolonged muscle contraction). ## Footnote Ex. Fainting goats.
37
What is myotonia caused by?
Electrical abnormalities of the sarcolemma due to inherited defects in the membrane ion channels.
38
What is hyperkalemic periodic paralysis (HYPP)?
A hereditary myopathy in horses that causes transient attacks of paralysis.
39
What is the difference between HYPP and myotonia?
HYPP is associated with hypotonia rather than hypertonicity.
40
What is hyperkalemic periodic paralysis (HYPP) caused by?
A mutation in muscle sodium channels.
41
What are metabolic myopathies characterized by?
Accumulation of intracytoplasmic glycogen in muscle fibers.
42
What is Equine Polysaccharide Storage Myopathy (EPSM)?
A metabolic myopathy in horses caused by accumulation of glycogen in muscle fibers.
43
What animals are affected by malignant hyperthermia?
Pigs, horses, and some dogs.
44
What is malignant hyperthermia caused by?
A defect in the ryanodine receptor gene.
45
What is the pathogenesis of malignant hyperthermia?
Stress or anesthesia → sudden increase in intracytoplasmic calcium → prolonged muscle fiber contraction.
46
What is malignant hyperthermia also called?
'Pale, soft, exudative pork.'
47
What is nutritional myopathy? What is it commonly referred to as?
A deficiency of selenium and Vitamin E. ## Footnote It is called white muscle disease.
48
What are ionophores?
Growth promoting feed additives for cattle and poultry.
49
What gross lesions do you see with ionophore toxicity?
Necrosis of cardiac muscle +/‐ skeletal muscle +/‐ myoglobinuria.
50
What is the muscle fiber damage in exertional myopathies caused by?
Exercise stress.
51
Exertional myopathies are associated with which two main clinical signs?
1. Rhabdomyolysis 2. Myoglobinuria.
52
What is capture myopathy?
A form of exertional myopathy that occurs in many species of wildlife.
53
What is circulatory myopathy?
When blood flow to a muscle is blocked.
54
What is compartment syndrome?
An example of a circulatory myopathy caused by increased intramuscular pressure.
55
What is downer syndrome?
An example of a circulatory myopathy caused by a heavy large animal sitting on their side.
56
What are clostridia?
Gram‐positive, anaerobic, and spore‐forming bacteria that exist within the environment.
57
What do clostridial bacteria produce?
Potent exotoxins.
58
What is blackleg caused by? What animal does it commonly occur in?
It is caused by Clostridium chauvoei and most commonly occurs in cattle.
59
What age of animal does blackleg affect?
9 months - 2 years old.
60
What does muscle look like that's infected with blackleg (grossly)?
Muscles are dark red to black and dull with gas bubbles, abundant yellow gelatinous edema.
61
What are three types of parasitic myositis?
1. Trichinellosis 2. Cysticercosis 3. Sarcocystosis.
62
True or False: Sarcocysts are a very common incidental finding in skeletal muscle of domestic herbivores.
True.
63
What is polymyositis of dogs?
A generalized immune‐mediated myositis.
64
What is masticatory muscle myositis?
An immune‐mediated myositis of the masticatory muscles.
65
What is the primary differential diagnosis for masticatory myositis?
Polymyositis.
66
What is masticatory muscle myositis caused by?
Auto‐antibodies directed against type 2M myosin.
67
How can you tell the difference between masticatory muscle myositis and polymyositis?
With masticatory myositis you see 2M myosin antibodies, but in polymyositis you don't.
68
Is rhabdomyoma benign or malignant?
Benign.
69
Is rhabdomyosarcoma benign or malignant?
Malignant.
70
What is rhabdomyosarcoma?
A malignant, locally invasive neoplasm that frequently metastasizes.
71
What location does rhabdomyosarcoma particularly like?
The bladder.
72
What are the two striated muscle neoplasms?
Rhabdomyoma and rhabdomyosarcoma.
Systemic Path
flashcards
Decks in class (35)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions