The present invention teaches minimally invasive apparatuses and methods for stabilizing and/or guiding medical instruments used in a variety of medical procedures, including (a) introducing one or more substances into a subject's body, (b) removing one or more substances from a subject's body, (c) manipulating a region of a subject's body, or (d) combinations thereof. Among the many advantages of the inventive apparatuses are their simplicity and adaptability to attach to a variety of retractors.