Surgical access system and related methods

A system for forming an operating corridor to a lumbar spine, comprising:

• an elongate member deliverable to a spinal disc along a lateral, trans-psoas path to the lumbar spine such that a distal tip region of the elongate member penetrates into an annulus of the spinal disc, the distal tip region of the elongate member including a stimulation electrode that delivers electrical stimulation for nerve monitoring during advancement of the elongate member along the lateral, trans-psoas path to the lumbar spine;
• a dilator system to create a distraction corridor along the lateral, trans-psoas path to the lumbar spine, the dilator system comprising at least one dilator that slidably engages an exterior of the elongate member, the at least one dilator being deliverable to the spinal disc along the lateral, trans-psoas path to the lumbar spine;
• a three-bladed retractor assembly slidable over the dilator system toward the spinal disc along the lateral, trans-psoas path, the three-bladed retractor assembly including:
• a handle assembly and first, second, and third retractor blades that extend generally perpendicularly relative to arm portions of the handle assembly,
• wherein the three-bladed retractor assembly is adjustable from a closed position in which the first, second, and third retractor blades are adjacent to one another and slidable over the dilator system to an opened position in which the second and third retractor blades are moved away from the first retractor blade to enlarge the distraction corridor and thereby form an operative corridor along the lateral, trans-psoas path to the lumbar spine, and
• wherein the second and third retractor blades are movable relative to the first blade in response to pivoting movement of two of the arm portions of the handle assembly,
• a posterior shim element to releasably engage with a posterior-most retractor blade of the first, second, and third retractor blades so that at least a portion of the posterior shim element extends distally from the posterior-most retractor blade to anchor into the spinal disc;
• and
• wherein when the three-bladed retractor assembly is adjusted to the opened position to form the operative corridor along the lateral, trans-psoas path to the lumbar spine, the first retractor blade is the posterior-most retractor blade of the first, second, and third retractor blades and the operative corridor is dimensioned so as to pass an implant through the operative corridor along the lateral, trans-psoas path to the lumbar spine.