Internal structure of a robotic surgical instrument

A robotic surgical instrument comprising a shaft, an end effector, and an articulation connecting the end effector to a distal end of the shaft. The articulation comprises joints permitting the end effector to adopt a range of orientations relative to a longitudinal axis of the shaft. Pairs of driving elements drive the joints, the driving elements extending through the shaft to the joints. An additional element extends through the shaft to the end effector via the articulation. A resilient barrier inside the shaft extends over a cross-sectional area of the shaft, the pairs of driving elements and the additional element passing through the resilient barrier, the resilient barrier being in resilient contact with the additional element so as to provide a resilient force opposing movement of the additional element; wherein each driving element of the pairs of driving elements passes through a hole in the resilient barrier without contacting the resilient barrier.