A surgical access system including a tissue distraction assembly and a tissue retraction assembly, 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. Some embodiments of the surgical access system may be particularly suited for establishing an operative corridor to a surgical target site in the spine. Such an operative corridor may be established through the retroperitoneal space and the psoas muscle during a direct lateral, retroperitoneal approach to the spine.