High-frequency treatment instrument

1. A high-frequency treatment instrument comprising:

a sheath;

an elongated extension member which is disposed in the sheath so as to freely extend and retract, the elongated extension member including:

a first linear portion disposed along the sheath, the first linear portion having a proximal end at a proximal side of the sheath and a distal end at a distal side of the sheath,

a first bent portion formed at the distal end of the first linear portion,

a third linear portion extending from the first bent portion toward a distal end of the sheath, the third linear portion having a proximal end at the proximal side of the sheath and a distal end at the distal end of the sheath,

a second bent portion formed at the distal end of the third linear portion, and

a second linear portion extending from the second bent portion, the second linear portion having a distal end at the proximal side of the sheath and a proximal end at the distal side of the sheath, and

a narrow portion provided on an inner surface of the sheath,

wherein

a pressing member is provided on the second linear portion, wherein the pressing member allows the distal end of the second linear portion to advance and retract only in a part of the sheath, wherein the part of the sheath is located proximal to the narrow portion,

when the second bent portion is protruded from the sheath while the first bent portion is inside of the sheath, a portion of the elongated extension member which protrudes from the sheath becomes a first treatment electrode which extends along a center axial line of the sheath, and

when the elongated extension member is advanced after the first treatment electrode is formed, the first bent portion protrudes from the sheath while advancement of the pressing member and the second linear member is suppressed by the narrow portion, and a part of the first treatment electrode between the first bent portion and the second bent portion becomes a second treatment electrode which intersects with the center axial line of the sheath,

wherein the high-frequency treatment instrument further comprises:

a control portion, which controls a protruding amount of the third linear portion and the second linear portion from the distal end of the sheath by directly contacting the narrow portion, is disposed at a position that is closer to a proximal end of the sheath than the second bent portion,

wherein the control portion is configured to be moved by movement of the first linear portion and the second linear portion toward a distal opening of the sheath until the control portion is moved into direct contact with the narrow portion.

2. A treatment instrument comprising:

a sheath having a distal end and a proximal end,

wherein the sheath is comprised of a sheath inner wall defining a sheath inner space extending along a longitudinal axis between the distal end and the proximal end,

wherein the sheath inner space opens to a sheath distal opening at the distal end of the sheath, and

wherein the sheath inner wall comprises an intermediate portion, a distal portion arranged distally of the intermediate portion along the longitudinal axis, and a proximal portion arranged proximally of the intermediate portion along the longitudinal axis;

a control tube configured to be guided by the proximal portion of the sheath inner wall to move along the longitudinal axis and to abut against the intermediate portion of the sheath inner wall; and

an operation wire comprising, in order between a first end of the operation wire and a second end of the operation wire: a first linear portion, a first bent portion, a second linear portion, a second bent portion, and a third linear portion; and

a pressing member fixed to the third linear portion of the operation wire,

wherein the pressing member is configured to be arranged in the sheath inner space at a position proximal to the control tube along the longitudinal axis and to abut against the control tube,

wherein the sheath, the control tube, the operation wire and the pressing member are configured to be arranged in a first configuration, a second configuration and a third configuration,

wherein in the first configuration, the second bent portion of the operation wire is arranged within the sheath inner space at a more distal position along the longitudinal axis than the second linear portion and the third linear portion,

wherein in the second configuration:

the control tube is guided by the proximal portion of the sheath inner wall to abut against the intermediate portion of the sheath inner wall to limit movement of the control tube in a distal direction along the longitudinal axis, and

the pressing member abuts against the control tube to limit movement of the third linear portion of the operation wire in the distal direction along the longitudinal axis such that the second bent portion of the operation wire is exposed through the sheath distal opening sheath and the first bent portion of the operation wire is maintained within the sheath inner space, and

wherein in the third configuration:

the control tube remains abutted against the intermediate portion of the sheath inner wall to limit movement of the control tube in the distal direction along the longitudinal axis,

the pressing member remains abutted against the control tube to limit movement of the third linear portion of the operation wire in the distal direction along the longitudinal axis such that the second bent portion of the operation wire remains exposed through the sheath distal opening and

the first linear portion of the operation wire is moved in the distal direction along the longitudinal axis such that the first bent portion and the second linear portion are exposed through the sheath distal opening.