Articulated arm (10, 10a, 10b) with the following characteristics: a first segment and a second segment, wherein the first segment is connected to a first hinged element and the second segment is connected to a second hinged element, and wherein the first and the second hinged elements are engaged in such a way that they form a rotating joint, wherein the second hinged element has a surface with at least partially constant curvature radius, and wherein the first segment has a knee lever mechanism, which is designed to exert a locking force onto the surface of the second hinged element in the direction of a face normal of the surface, wherein the knee lever mechanism comprises a first lever (22a, 22a') and a second lever, which are connected to each other using a common hinge (24c, 24c'), wherein the first lever (22a, 22a') is positioned on the first segment using a first bearing so that a rotation of the first lever (22a, 22a') relative to the first segment around a first pivot point is possible, and so that further degrees of freedom are limited and/or restricted, and wherein the second lever is positioned on the first segment using a second bearing (24b, 24b') so that a rotation of the second lever relative to the first segment around a second pivot point (24b, 24b') is possible, wherein the second pivot point (24b, 24b') can be moved along the longitudinal axis of the first segment, and so that further degrees of freedom are limited and/or restricted, characterized in that a maximum distance between the first and the second pivot point (24a, 24b, 24b') is limited in such a way that the statically over-determined area is formed along the track of motion of the common hinge (24c, 24c') of the first and the second lever (22a, 22a', 22b) around the first pivot point, and in that the first bearing is designed so that the first pivot point is positioned outside the longitudinal axis of the first segment. a first segment and a second segment, wherein the first segment is connected to a first hinged element and the second segment is connected to a second hinged element, and wherein the first and the second hinged elements are engaged in such a way that they form a rotating joint, wherein the second hinged element has a surface with at least partially constant curvature radius, and wherein the first segment has a knee lever mechanism, which is designed to exert a locking force onto the surface of the second hinged element in the direction of a face normal of the surface, wherein the knee lever mechanism comprises a first lever (22a, 22a') and a second lever, which are connected to each other using a common hinge (24c, 24c'), wherein the first lever (22a, 22a') is positioned on the first segment using a first bearing so that a rotation of the first lever (22a, 22a') relative to the first segment around a first pivot point is possible, and so that further degrees of freedom are limited and/or restricted, and wherein the second lever is positioned on the first segment using a second bearing (24b, 24b') so that a rotation of the second lever relative to the first segment around a second pivot point (24b, 24b') is possible, wherein the second pivot point (24b, 24b') can be moved along the longitudinal axis of the first segment, and so that further degrees of freedom are limited and/or restricted, characterized in that a maximum distance between the first and the second pivot point (24a, 24b, 24b') is limited in such a way that the statically over-determined area is formed along the track of motion of the common hinge (24c, 24c') of the first and the second lever (22a, 22a', 22b) around the first pivot point, and in that the first bearing is designed so that the first pivot point is positioned outside the longitudinal axis of the first segment.