Steerable instrument comprising a cylindrical diameter adaptation section

A steerable instrument for at least one of endoscopic and invasive type of applications, the instrument comprising an elongated tubular body having at least a first actuation zone at a proximal side of the steerable instrument and at least a first bendable zone at a distal side of the steerable instrument, the first actuation zone being configured to control bending of the first bendable zone by means of a plurality of longitudinal steering elements, the steerable instrument having a cylindrical diameter adaptation section located proximally from the first bendable zone and comprising a first side and a second side,

• wherein
• the longitudinal steering elements comprise at least a first set of one or more longitudinal steering elements and a second set of one or more longitudinal steering elements,
• said one or more longitudinal steering elements of the first set of longitudinal steering elements are defined by longitudinal slits provided in a wall of a first cylindrical tube and are located at a first distance from an axis of symmetry at said first side as well as within said cylindrical diameter adaptation section, the first cylindrical tube having a first radius equal to said first distance,
• said one or more longitudinal steering elements of the second set of longitudinal steering elements are defined by longitudinal slits provided in a wall of a second cylindrical tube and are located at a second distance from said axis of symmetry at said second side as well as within said cylindrical diameter adaptation section, said second distance being different from said first distance, the second cylindrical tube having a second radius equal to said second distance,
• each longitudinal steering element of the first set of one or more steering longitudinal steering elements is overlapping with one longitudinal steering element of the second set of one or more longitudinal steering elements within said cylindrical diameter adaptation section in an area of overlap as seen in a radial direction from said axis of symmetry, and each longitudinal steering element of the first set of one or more longitudinal steering elements is connected and/or attached to one longitudinal steering element of the second set of one or more longitudinal steering elements in the area of overlap, such that a movement of each longitudinal steering element of the first set of one or more longitudinal steering elements in a longitudinal direction of said steerable instrument results in a same movement of said one longitudinal steering element of the second set of one or more longitudinal steering elements to which it is connected and/or attached in said longitudinal direction.