Minimally invasive surgical techniques are used to obtain access to vertebrae while protecting soft tissues in the surrounding area. The dilators may be used to provide a working channel through which the operation is performed. Standard dilators may be used with a robotic surgical system to provide precise guidance of surgical tools. A dilator may be held by the robot and automatically repositioned when the surgeon adjusts a trajectory for performing the surgery. The dilator itself may be used as a surgical instrument guide along with dilator adaptors that adjust the diameter of a portion of the dilator to allow for different sized tools to be guided by the dilator. Alternatively, surgical instrument guides may also be held by the robotic arm such that tools are guided by a surgical instrument guide through the dilator to perform a medical procedure.