The invention relates to a medical instrument comprising an elongated element, which is preferably configured for transoral placement in a stomach, and an end effector (100) arranged at one end of the elongated element, wherein the end effector (100) can be operated by means of a hydraulic operating mechanism (1), wherein the hydraulic operating mechanism (1) comprises a cylinder (20) having at least one, preferably two, three, four, or five, overflow channels (21a, 21b, 21c, 21d) for a hydraulic fluid, which are connected to the cylinder interior by means of at least one bore (22, 22b, 22b′, 22c, 22c′, 22d, 22d′), a piston (30) arranged in the cylinder (20) and movable along the longitudinal axis of the cylinder (20) is provided, wherein the piston (30) divides the interior (23) of the cylinder (20) into a first cylinder chamber (23a) and a second cylinder chamber (23b) and is connected to the end effector (100) by means of a piston rod (31), and at least one connection (41) for introducing hydraulic fluid into the first cylinder chamber (23a) and at least one further connection (41a, 41b, 41c, 41d), which is connected to at least one overflow channel (21a, 21b, 21c, 21d) of the cylinder (20), are provided.
