A transmission adapter for a medical instrument having a shaft, a transmission element that can move within the shaft and an operating device with a first part, which can be mechanically rigidly coupled with a proximal end of the shaft, and a second part, which can move with respect to the first part, includes a first coupling for releasable mechanical coupling with the second part of the operating device and a second coupling for releasable mechanical coupling with a proximal end of the transmission element.