Anesthesia · single question
Local anesthetics block conduction in myelinated nerve fibers principally at the:
Show answer and explanation
Correct answer: B. Nodes of Ranvier
- A. Incorrect – not the site of LA sodium-channel blockade.
- B. Correct – in myelinated fibers voltage-gated Na+ channels are concentrated at the nodes; blocking enough consecutive nodes stops saltatory conduction.
- C. Incorrect – internodes are insulated by myelin and have few Na+ channels.
- D. Incorrect – the action of LA is at the axonal membrane, not the soma.