A minimally invasive medical instrument comprises an elongate flexible body including a proximal portion, a distal portion, an inner sheath defining a central lumen, and an outer sheath. The inner sheath comprises an inner surface and an outer surface. The instrument further comprises a plurality of conduits embedded within the inner sheath. The plurality of conduits extend through the inner sheath and terminate within the inner sheath. Each conduit includes a conduit lumen and a distal end, and the distal end is directly secured to the inner sheath. The instrument further includes at least one tendon extending through the conduit lumen of at least one conduit of the plurality of conduits from the proximal portion and beyond the distal end of the at least one conduit into the distal portion of the elongate flexible body. The at least one tendon is actuatable to steer the distal portion.