Bending portion of endoscope and endoscope

An insertion section for an endoscope, the insertion section comprising:

• a frame member;
• a bending piece group comprising a plurality of first bending pieces arranged along a longitudinal axis direction, each of the first bending pieces including first contact surfaces formed on a proximal end surface of each of the first bending pieces and second contact surfaces formed on a distal end surface of each of the first bending pieces, the first and second contact surfaces facing the longitudinal axis direction, each of the first bending pieces having a first opening for allowing insertion of a plurality of internal components along the longitudinal axis direction, the first opening having a first shape in a plane orthogonal to the longitudinal axis direction, the bending piece group being provided along the longitudinal axis direction such that the first contact surfaces and the second contact surfaces of the first bending pieces adjacent to each other are rotatably in contact with each other;
• a second bending piece comprising coupling portions on a distal end side of the second bending piece, and third contact surfaces on a proximal end side of the second bending piece, the coupling portions being configured to couple the second bending piece to the frame member disposed at a distal end portion of the second bending piece such that the second bending piece resists torsion about a longitudinal axis, the third contact surfaces facing the longitudinal axis direction, the second bending piece having a second opening for allowing insertion of the plurality of internal components, the second opening having a second shape in a plane orthogonal to the longitudinal axis direction, the second shape having a second outer contour being aligned with at least a portion of a first outer contour of the first shape when projected in the longitudinal axis direction, the second bending piece connected to the bending piece group such that the third contact surfaces of the second bending piece and the second contact surfaces of the first bending piece located at a distal-most position of the bending piece group are rotatably in contact with each other;
• and
• the plurality of internal components extending in the longitudinal axis direction through the first opening of each of the plurality of first bending pieces of the bending piece group, through the second opening of the second bending piece and are fixed to respective fixed positions of the frame member,
• wherein the coupling portions are coupled to the frame member through rivets so as to be rotatable about an axis in a direction orthogonal to the longitudinal axis,
• the rivets are arranged at positions shifted by 90 degrees about the longitudinal axis with respect to a direction in which the third contact surfaces are provided,
• a first arrangement of the plurality of internal components are changed from the respective fixed positions in the frame member to a second arrangement defined by the second shape of the second opening of the second bending piece;
• and
• the second arrangement is maintained in the plurality of first bending pieces of the bending piece group by the first shape of the first opening.