An introducer is described that is coupled to a patient, specifically a patient's skull. The introducer may include an advancer that is remote from the patient, the advancer communicating with the introducer by means of a cable system. The introducer may also include a local position sensor that indicates the position of the primary medical device being introduced. The introducer may also include a frameless reference system that locates the primary medical device relative to a table that the patient is fixed to.