Abstract: Systems, devices, and methods for tissue retraction include one or more instruments operatively couplable for retracting and/or retaining tissues or other materials during a procedure. In one aspect, a first instrument includes an elongate rigid body having a longitudinal axis extending from a proximal end to a distal end. The elongate rigid body has an outer polygonal profile and an interior surface defining a round channel extending along the longitudinal axis. The round channel may receive a tubular instrument therethrough. The elongate rigid body includes one or more sets of flanges protruding from lateral sides of the outer polygonal profile. The flanges positively engage one or more respective tracks of a tissue retraction blade. Additional instruments may be provided that operatively couple to the first instrument and/or to one or more tissue retractor blades, for example while the first instrument is coupled to the tissue retractor blades.