1. An apparatus to map the location of a nerve, the apparatus comprising: a stimulation module that stimulates a nerve with an electrical stimulation current from at least one stimulation electrode; a stimulation detection module that detects a muscle reaction, the muscle reaction resulting from stimulation of the nerve by the at least one stimulation electrode; a distance module that uses information from the at least one stimulation electrode and from the stimulation detection module to calculate a distance between the at least one stimulation electrode and the nerve; and a mapping module that maps a location on the nerve using at least two distances calculated by the distance module and position information of the at least one stimulation electrode for each of the at least two distances calculated.