Abstract: A surgical system includes: an overtube including a channel into which an endoscope is inserted; and an expansion device configured to ensure a surgical space by expanding an interior of a body at a distal side relative to a tip of the overtube. The expansion device includes a sheath and a wire configured to be protrudable from the sheath. The wire is configured to be switchable between a first configuration in which the wire protrudes from the sheath and a second configuration in which the wire protrudes from the sheath in a state where the wire is tilted, around a longitudinal axis, at an angle different from the first configuration.

Abstract: The technology disclosed herein is directed to an over-tube, an endoscopic system, and a cap which is constructed to identify with greater certainty from which position a medical instrument inserted in a channel will project on the distal end of the over-tube. The over-tube includes a tubular member and a protrusion. The tubular member includes at least a treatment tool channel into which a treatment tool is inserted and an endoscope channel into which an endoscope device is inserted. The protrusion protrudes radially inwardly from at least a portion of an inner circumferential surface of the endoscope channel in a longitudinal direction thereof. The protrusion indicates a position configuration in a circumferential direction of the treatment tool channel with respect to the endoscope channel. The endoscope captures an image that includes the protrusion and the protrusion in the acquired image confirms the position configuration of the treatment tool channel.