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...http://www.google.fr/patents/US20100130827?utm_source=gb-gplus-shareBrevet US20100130827 - SURGICAL ACCESS SYSTEM AND RELATED METHODS
