Patent ID: 11867897

Abstract:
An insertion assisting instrument has an outer diameter dimension set to satisfy a relationship of xb′<xc′ assuming that an insertion assisting instrument is projected on X-Y coordinates such that a point on a circumference where the insertion assisting instrument has a largest outer diameter (that is, a point on an outer periphery of a proximal-end-side tapered surface at a distal end) is set as an origin and the proximal-end-side tapered surface is brought into contact with an X axis, coordinates of a second point B, which is most distal from the X axis on the circumference where the insertion assisting instrument has the largest outer diameter are (xb′, yb′), and coordinates of a third point C, which is most proximal from the X axis on a circumference at the proximal end of the insertion assisting instrument, are (xc′, yc′).