A device for retracting tissue provides access to a spinal location within a patient. The device includes an elongate body and a passage. The elongate body has a proximal portion and a distal portion. The elongate body defines a length between the proximal and distal portions along a longitudinal axis...http://www.google.ca/patents/US7976464?utm_source=gb-gplus-sharePatent US7976464 - Access systems and methods for minimally invasive surgery
