Synaptic transmission and the neuromuscular junction
Step-by-step transmission at the neuromuscular junction, the safety factor, and how myasthenia gravis, Lambert-Eaton syndrome, botulism, organophosphates and neuromuscular blocking drugs each break a different step, with the repetitive nerve stimulation patterns that tell them apart.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The neuromuscular junction is a nicotinic cholinergic synapse with a large safety factor: the end-plate potential is normally about 3 to 5 times larger than needed to fire the muscle fibre.
- Weakness appears when a disease or drug erodes that margin. Presynaptic problems (Lambert-Eaton, botulism) reduce release; postsynaptic problems (myasthenia gravis, non-depolarising blockers) reduce receptor response.
- Fatigable weakness without sensory loss, normal reflexes (or reflexes that return after exercise in Lambert-Eaton) and autonomic features point to the junction.
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Sources
- Principles of Neural Science (6th ed.)McGraw Hill (Kandel, Koester, Mack and Siegelbaum, 2021), 2021
- Therapeutic Guidelines: NeurologyAU/NZTherapeutic Guidelines Limited, 2023
- Narayanaswami P et al. International consensus guidance for management of myasthenia gravis: 2020 update. Neurology 2021;96:114-22Neurology, 2021
- Gilhus NE et al. Myasthenia gravis. Nat Rev Dis Primers 2019;5:30Nature Reviews Disease Primers, 2019
- Wood SJ, Slater CR. Safety factor at the neuromuscular junction. Prog Neurobiol 2001;64:393-429Progress in Neurobiology, 2001
- Last updated
- 14 November 2026
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