An endoscopic instrument includes a control wire having a push rod at its distal end and an end effector assembly having first and second effector elements such as scissors blades mounted on a clevis. The effector elements are operated by a cam-pin on the push rod riding in cam-slots defined in the effector elements. According to one aspect of the invention, the effector elements are symmetrically opened even when the push rod is canted relative to the clevis. According to another aspect of the invention, the effector elements can be rotated into a closed configuration that minimizes the distal dimension across the effector elements. In addition, the effector elements, when in the closed configuration, can rotate together to facilitate insertion of the end effector into an entry portion of an endoscope.
