Articulable introducer sheaths and related methods and systems for accessing various surgical sites are disclosed. An introducer sheath comprises a tubular body and a filament. The tubular body has a proximal portion, a distal portion, and a central lumen. The filament is constrained on or within at least a portion of the proximal portion and unconstrained over at least a portion of the distal portion. The distal end of the filament is held or attached near a distal end of the tubular body so that advancement of the filament relative to the tubular body causes the unconstrained portion to bow out or extend radially outward, such as to engage a body tissue so as to steer the tubular body when the tubular body has been introduced into a surgical site, such as an epidural space. A surgical tool or medical implant can then be advanced through the sheath.
