Mantle tube and treatment tool

1. A mantle tube, comprising:

a bendable member formed to be received in an elongate, annular, cylindrical member, the bendable member including two fixed sites that are fixed to the cylindrical member and a bendable site that is interposed between the fixed sites and bendable in a direction intersecting a longitudinal direction thereof, so that the cylindrical member is bent following the bendable site in the direction intersecting a longitudinal direction thereof,

an angle adjustment member capable of adjusting a bending angle of the bendable site, and

an angle holding mechanism capable of holding the bendable site bent by the angle adjustment member at any desired bending angle;

wherein the angle holding mechanism comprises:

a flexible wire member extending along the bendable member, the flexible wire member being fixed at one end to a front-end side fixed site of the bendable member,

a plurality of interconnected structure-forming members arranged along the wire member and capable of coming into contact with one another, the plurality of interconnected structure-forming members being spaced away from one another in an arrangement direction, and

a pressing member for causing the interconnected structure-forming members to be guided by the wire member so that the interconnected structure-forming members are pressed together along the arrangement direction so as to come close to one another,

wherein the plurality of interconnected structure-forming members are pressed together by the pressing member in the arrangement direction whereby an interconnected state thereof bent following a bent shape of the bendable member is maintained by friction.

2. The mantle tube as recited in claim 1 , wherein:

the bendable member includes at least two the bendable sites that are capable of bending in mutually different directions, and

the angle adjustment member is capable of angle adjustment for each of the bendable sites.

3. The mantle tube as recited in any one of claim 1 , wherein:

the wire member is inserted through all of the interconnected structure-forming members in the arrangement direction and fixed to the interconnected structure-forming member at a foremost end, and

the pressing member applies a press to the interconnected structure-forming member at a rearmost end, the press being toward the foremost end of the arrangement direction.

4. The mantle tube as recited in any one of claim 1 , wherein:

the interconnected structure-forming member includes a spherical connecting surface having a mutual correlation to an adjoining other interconnected structure-forming member.

5. The mantle tube as recited in any one of claim 1 , wherein:

the interconnected structure-forming member includes a connecting portion having a mutual correlation to an adjoining other interconnected structure-forming member, and those connecting portions are connected together to impose limitation on a bending of the bendable member in a direction intersecting a bending direction of the bendable member.

6. The mantle tube as recited in any one of claim 1 , wherein:

the angle holding mechanism includes a resilient member interposed between adjoining ones of the interconnected structure-forming members, the resilient member being capable of absorbing force of contact of the interconnected structure-forming members with each other.

7. The mantle tube as recited in any one of claim 1 , wherein:

the bendable member includes an insertion path through which a medical device is insertable, and

the angle holding mechanism is located outside of the insertion path of the bendable member.