Surgical access system and related methods

A system for accessing a spinal disc of a lumbar spine through an operative corridor, comprising:

• a distraction assembly to create a tissue distraction corridor to a lumbar spine, wherein said distraction assembly comprises:
• an elongate inner member deliverable toward a spinal disc along a lateral, trans-psoas path to the lumbar spine, and at least two supplemental dilators of sequentially larger diameter configured to be delivered to the spinal disc along the lateral, trans-psoas path to the lumbar spine, a first supplemental dilator of the at least two dilators having a lumen configured to slidably receive the elongate inner member, a second supplemental dilator of the at least two dilators being advanceable over the first supplemental dilator along the lateral, trans-psoas path to the lumbar spine, wherein at least one instrument from the group consisting of the elongate inner member, the first supplemental dilator, and the second supplemental dilator includes a stimulation electrode to deliver electrical stimulation for nerve monitoring when said stimulation electrode is positioned in the lateral, trans-psoas path to the lumbar spine;
• and
• a retraction assembly comprising a plurality of retractor blades configured to enlarge the tissue distraction corridor and configured to maintain a trans-psoas operative corridor along the lateral, trans-psoas path to the lumbar spine when the plurality of retractor blades are delivered to the lumbar spine, the retraction assembly further comprising a blade holder apparatus that is capable of retaining the first and second retractor blades in an orientation in which the first retractor blade is spaced apart from the second retractor blade by a gap therebetween, and blade holder apparatus being configured to retain the plurality of retractor blades in a selected position to maintain the trans-psoas operative corridor that is so dimensioned to pass a spinal implant through the trans-psoas operative corridor along the lateral, trans-psoas path to the lumbar spine.