Botulinum toxins exert their action by targeting the nervous system, specifically at the neuromuscular junction. These neurotoxins are produced by Clostridium botulinum and are among the most potent known toxins. They work by cleaving key proteins involved in neurotransmitter release, primarily acetylcholine, which is crucial for muscle contraction. Botulinum toxins bind to presynaptic nerve terminals and are internalized into the nerve cell. Once inside, they target and cleave SNARE proteins, such as SNAP-25, synaptobrevin, or syntaxin, depending on the toxin type. These proteins are essential for the fusion of synaptic vesicles with the cell membrane, a process that allows acetylcholine to be released into the synaptic cleft. By inhibiting this release, botulinum toxins effectively prevent muscle contraction, leading to muscle paralysis. This mechanism underlies the therapeutic use of botulinum toxins in conditions like spasticity, dystonia, and cosmetic treatments, where temporary muscle relaxation is desired.