Articulation joint features for articulating surgical device

An apparatus comprising:

• (a) a body;
• (b) an end effector comprising:
• (i) a first jaw, and
• (ii) a second jaw, wherein the first and second jaws are operable to clamp tissue therebetween;
• and
• (c) a shaft assembly extending between the body and the end effector, wherein the shaft assembly comprises:
• (i) a proximal shaft portion defining a longitudinal axis, and
• (ii) an articulation section extending between the proximal shaft portion and the end effector, wherein the articulation section is operable to selectively articulate the end effector relative to the longitudinal axis, wherein the articulation section comprises:
• (A) a proximal section end coupled to the proximal shaft portion,
• (B) a distal section end coupled to the end effector,
• (C) a first longitudinal portion extending from the proximal section end to the distal section end, and
• (D) a second longitudinal portion extending from the proximal section end to the distal section end,
• wherein the first and second longitudinal portions are configured to mate to define a body of the articulation section.

An apparatus comprising:

• (a) a body;
• (b) an end effector comprising:
• (i) a first jaw, and
• (ii) a second jaw, wherein the first and second jaws are operable to clamp tissue therebetween;
• and
• (c) a shaft assembly extending between the body and the end effector, wherein the shaft assembly comprises:
• (i) a proximal shaft portion defining a longitudinal axis, and
• (ii) an articulation section extending between the proximal shaft portion and the end effector, wherein the articulation section is operable to selectively articulate the end effector relative to the longitudinal axis, wherein the articulation section comprises:
• (A) a proximal section portion coupled to the proximal shaft portion,
• (B) a distal section portion coupled to the end effector, and
• (C) a spine extending continuously between the proximal and distal section portions, wherein the spine has a first width at the proximal section portion and a different second width at the distal section portion.

An apparatus comprising:

• (a) a body;
• (b) an end effector comprising:
• (i) a first jaw, and
• (ii) a second jaw, wherein the first and second jaws are operable to clamp tissue therebetween;
• and
• (c) a shaft assembly extending between the body and the end effector, wherein the shaft assembly comprises:
• (i) a proximal shaft portion defining a longitudinal axis, and
• (ii) an articulation section extending between the proximal shaft portion and the end effector, wherein the articulation section is operable to selectively articulate the end effector relative to the longitudinal axis, wherein the articulation section comprises:
• (A) a proximal section portion coupled to the proximal shaft portion,
• (B) a distal section portion coupled to the end effector, and
• (C) a flexible section portion extending between the proximal and distal section portions, wherein the flexible section portion has a flexibility that increases distally.