A trajectory guide for providing access to a target site of a living subject along a desired path comprises a baseplate including a clamp lock, a guide member at least partially contained within the baseplate and having a channel therein, a plurality of adjustable legs each including a first end and a second end, wherein the first end is coupled to the baseplate, and a leg lock coupled to each adjustable leg and moveable between an unlocked position and a locked position in order to set a desired length of the adjustable leg, wherein the adjustable legs and the guide member are structured to be adjusted to provide an infinite number of trajectories in three-dimensional space extending through the channel in the guide member toward a target.