Why does botulinum toxin (Botox) injection cause localized muscle paralysis, even though action potentials still propagate along the motor neuron?

💡 Explanation

Botox cleaves SNARE proteins, preventing the fusion of acetylcholine (ACh)-containing vesicles with the presynaptic membrane; therefore, ACh is not released into the synaptic cleft to depolarize the muscle endplate and trigger muscle contraction, because Botox acts presynaptically, rather than by blocking action potentials or directly affecting muscle proteins.

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