Disclosed is a surgical instrument comprising an instrument handle, an instrument shaft shaft having a distal end and a proximal end at which the instrument handle is linked, an instrument head, pivotally linked to the distal end of the instrument shaft via a hinge shaft or pins and comprising an effector rotatably supported in said instrument head around its longitudinal axis as well as a surgical tool held by said effector, and a mechanical transmission system at least partially arranged within said instrument shaft transmitting mechanical operation signals from said instrument handle to said instrument head at least for pivoting and/or rotating motions. A bending flexible as well as rotating rigid, hollow spindle is arranged bypassing said hinge shaft or pins and directly connecting said effector with the mechanical transmission system for transmitting at least rotating signals via said spindle to said effector.