Nodes of Ranvier
Nodi fibrae nervosae (Ranvier)
NervousNervesWhole body
- What it is
- Short bare gaps between neighbouring myelin segments, where the axon membrane is exposed and densely packed with voltage-gated sodium channels.
- Function
- Regenerate the action potential at each gap so the signal leaps from node to node instead of creeping along the whole membrane.
- Size
- About 1 micrometre long, spaced 0.2-2 mm apart
- Clinical note
- Local anaesthetics work by blocking the sodium channels at the nodes; blocking about three nodes in a row stops conduction completely.