A method and apparatus accurately maintains alignment of a surgical instrument. The apparatus includes a base with an attached movable member. The movable member includes a passage forming a portion of a trajectory path. A relaxable or rigid material has a similar passage in common with the passage of the movable member. If a relaxable material is used, the passage portion of the relaxable region is held open by an inserted stem removably attached to the movable member. The instrument is then inserted into the center of the stem and thus into the trajectory path. The stem is removed by withdrawing it from the movable member over the proximal portion of the instrument. This releases the relaxable region to tightly hold the instrument in place. Alternatively, using a relaxable or rigid component, the component is slid laterally to at least partially offset a passage through the component from the passage of the movable member to reduce a combined effective area of the passages and to grasp an instrument.