Patent ID: 8241279

Claim:
An overtube comprising: an insertion portion that has a distal end portion and a proximal end portion, at least the distal end portion being inserted into an examination subject; a first lumen that is formed along a longitudinal direction of the insertion portion and into which a device for carrying out medical procedures in the examination subject is freely slidable; an opening that is formed at the distal end of the insertion portion and that communicates with the first lumen; a tissue cutting portion provided in the first lumen, the tissue cutting portion being capable of traversing the first lumen in a direction which intersects a longitudinal direction of the first lumen and to project from and retract into the opening for cutting a tissue of the examination subject; an accommodation portion comprising a holding portion that is formed in the first lumen; a controlling member movable in the longitudinal direction of the first lumen; and an operation portion which controls a moving of the controlling member, wherein the tissue cutting portion has a restoring force which restores the tissue cutting portion from a second position to a first position; the holding portion constrains the tissue cutting portion so as to prevent restoring of the tissue cutting portion from the second position to the first position due to the restoring force; the holding portion includes a puncture needle which freely advances and retracts relative to the tissue cutting portion, engaging and intersecting the tissue cutting portion which is deformed from a state of traversing the first lumen to a state of bending to a direction separating from an axis of the first lumen to a radial direction; the first position indicates a position where the tissue cutting portion traverses the first lumen in a direction which intersects the longitudinal direction of the first lumen, and the second position indicates a position where the tissue cutting portion is removed from the first position.