 Node of Ranvier

A node of Ranvier is a short gap between adjacent myelin sheaths along an axon. Its exposed cell membrane contains a high density of voltage-dependent sodium channels, allowing an action potential to be regenerated after local electric current has spread beneath the preceding sheath. Repetition of this arrangement supports saltatory conduction.^[ref]

A node is not a gap in the axon itself. The interior remains continuous while the surrounding insulation is interrupted. This distinction explains how current can travel between electrically excitable regions without crossing a synapse.