Muscle Contraction

Question 1

What happens during voluntary muscle contraction?

Answer 1

• muscle fiber stretched - spindles sense stretch and activate sensory nerves
• Nerves relay message from muscle to Alpha Motor Neuron and back

Question 2

What is the Alpha motor neuron?

Answer 2

• Final common pathway in CNS
• for afferent impulses from muscle to CNS
• multiple terminal branches produce large contraction
• minimal terminal branches produce discrete contractions

Question 3

What is a spasm?

Answer 3

prolonged contraction as CNS attempts to protect muscle following chemical or physical trauma

• marked by sensory bombardment of alpha motor neuron
• often exercise induced due to electrolyte imbalances

Question 4

What are the oral skeletal muscle relaxants used for muscle spasms?

Answer 4

1) Dantrolene
2) Chlorzoxazone
3) Carisoprodol
4) cyclobenaprine
5) methocarbamol
6) diazepam
7) baclofen
8) skelakin

Question 5

What is the MOA for Dantrolene?

Answer 5

inhibits calcium influx into cells of skeletal muscle

Question 6

What is the MOA for chlorzoxazone?

Answer 6

unknown…CNS depression - no effect on neuromuscular transmission

Question 7

What is the MOA for Carisoprodol?

Answer 7

CNS depression - no effect on neuromuscular transmission

Question 8

What is the MOA for cyclobenzaprine (flexeril)?

Answer 8

unknown…CNS depression - no effect on neuromuscular transmission

Question 9

What is the MOA for Diazepam (valium)?

Answer 9

enhances gamma-aminobutyric acid
- chloride influx into cells of cns
Used for anxiety, acute alcohol withdrawal, muscle relaxant

Question 10

What is the MOA for baclofen?

Answer 10

affects spinal cord - used for MS