Saltatory conduction is the mode of action potential propagation in myelinated axons in which the impulse jumps node to node of Ranvier, rather than spreading continuously (Latin saltare, to jump).
It occurs because myelin insulates the internode and confines Na+ channels to the nodes.
Determinants of Conduction Velocity
Conduction velocity is directly proportional to two factors: degree of myelination and axon diameter, since larger fibers offer less cytoplasmic resistance to ion flow.
Unmyelinated and myelinated axons both obey this same rule; myelination and diameter are the two determinants shared by both modes of conduction.