A surgical probe and a method for forming and enlarging an access opening through a psoas muscle to provide for minimally invasive lateral approach for surgical access to a lumber intervertebral disc. A distal end portion of the probe is equipped with an electrode useful for confirming proper location of the probe and includes an inflatable dilator body for enlarging an access opening through tissue adjacent to a spinal column. The probe includes a cannula through which a K wire can be extended to anchor the probe to a patient.