Do nerve impulses move at 90 m/s?

About 90 m/s is plausible for some large, well-myelinated nerve fibers, but it is not a universal speed for all nerve signals. Conduction in unmyelinated axons may be about 0.5–10 m/s, while myelinated axons can reach roughly 150 m/s. Speed depends on axon diameter, myelination, and fiber type. Thus, 90 m/s is one possible high value, not a general constant.