Why is no cell energy spent in the myelinated stretches of an axon?

1. Energy is spent when ions are driven across a membrane to build an action potential. 2. Inside a myelinated stretch no action potential forms at all. 3. With no action potential there is nothing to pay for, so no cell energy is used there. 4. The signal simply runs along as it would in an ordinary conductor, losing some voltage as it goes. 5. It is rebuilt at full voltage only in the bare gaps, where an action potential does fire. 6. Amplification inside the sheath would require an energy source, which is exactly what is absent. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section Nerve Conduction_