Which medication works by acting directly on skeletal muscle to relieve spasticity?

Which medication works by acting directly on skeletal muscle to relieve spasticity?

• A. Inhibits acetylcholine release at NMJ
• B. Increases CNS excitability
• C. Acts directly on skeletal muscle to relieve spasticity
• D. Inhibits calcium uptake in smooth muscle

Answer: (C)

Spasticity can be treated by drugs that act in the CNS or by agents that work directly on the muscle itself. When a medication acts directly on skeletal muscle, it changes the muscle fiber’s internal machinery to reduce contraction. A classic example is dantrolene, which blocks calcium release from the sarcoplasmic reticulum inside skeletal muscle cells. With less intracellular calcium, the interaction between contractile proteins is diminished, so the muscle is less able to contract. This is a direct muscle effect, not a central nervous system effect or a modulation at the neuromuscular junction. The other ideas describe actions at different sites: inhibiting acetylcholine release at the neuromuscular junction reduces activation at the connection between nerve and muscle, not inside the muscle fiber itself; increasing CNS excitability would worsen spasticity; and inhibiting calcium uptake in smooth muscle doesn’t apply to skeletal muscle.

Spasticity can be treated by drugs that act in the CNS or by agents that work directly on the muscle itself. When a medication acts directly on skeletal muscle, it changes the muscle fiber’s internal machinery to reduce contraction.

A classic example is dantrolene, which blocks calcium release from the sarcoplasmic reticulum inside skeletal muscle cells. With less intracellular calcium, the interaction between contractile proteins is diminished, so the muscle is less able to contract. This is a direct muscle effect, not a central nervous system effect or a modulation at the neuromuscular junction.

The other ideas describe actions at different sites: inhibiting acetylcholine release at the neuromuscular junction reduces activation at the connection between nerve and muscle, not inside the muscle fiber itself; increasing CNS excitability would worsen spasticity; and inhibiting calcium uptake in smooth muscle doesn’t apply to skeletal muscle.