Targeting the neuromuscular junction in skeletal muscles.

Botulinum neurotoxins selectively weaken skeletal muscle by presynaptic blockade of vesicles containing the neurotransmitter acetylcholine. Because the location of the neuromuscular junction (found in motor endplates) is most highly concentrated in a band within the midbelly of the muscle, injection of botulinum neurotoxins are hypothesized to be more potent when specifically targeted toward the motor endplate zones. Few studies have attempted to describe the distribution of motor endplate zones in skeletal muscles, and scant experimental data exist that directly tests this hypothesis. In this article, a rationale is presented for motor endplate targeting within specific limb muscles with respect to botulinum neurotoxin therapy.