A prosthesis (1) for providing at least one mechanically operable digit member. The prosthesis (1) has at least one digit member (3) extending generally tangentially with respect to a fixed worm gear wheel means (5) on a support member of the prosthesis and mounted for rotation about the worm gear wheel means axis (8). The digit member has a drive motor (7) operable to drive a worm means (13). The worm means (13) is in engagement with the worm gear wheel means (5) so that when the drive motor is operated, in use of the prosthesis, the digit member (3) moves around the worm gear wheel means (5), in which the worm means (13) is disposed outwith the digit member (3).