The transmission adapter (60) has a shaft (30), a transmission device (50) movable in the shaft and a handling device (20) with a first portion (21) and a second portion (22). The first portion is mechanically rigidly coupled with a proximal end (31), and a second potion is movable relative to the first portion. A first coupling (61) is provided for a releasable mechanical coupling with the second potion of the handling device. A second coupling (68) is provided for releasable mechanical coupling with another proximal end (51) of the transmission device. Independent claims are included for the following: (1) a shaft with an opening； and (2) a medical instrument.
