A system for accessing a surgical target site and related methods,
involving an initial distraction system for creating an initial
distraction corridor, and an assembly capable of distracting from the
initial distraction corridor to a secondary distraction corridor and
thereafter sequentially receiving a plurality of retractor blades for
retracting from the secondary distraction corridor to thereby create an
operative corridor to the surgical target site, both of which may be
equipped with one or more electrodes for use in detecting the existence
of (and optionally the distance and/or direction to) neural structures
before, during, and after the establishment of an operative corridor to a
surgical target site.