A surgical robotic instrument comprising: an articulation 505 connecting an end effector element to a shaft 504, the articulation comprising: a first joint 506 driveable by a first pair of driving elements A1,A2 allowing the end effector element to rotate about a first axis 510； a second joint 507 driveable by a second pair of driving elements B1,B2； and a pulley arrangement around which the second pair of driving elements B1,B2 is constrained to move. The pulley arrangement comprising: a first set of pulleys rotatable about the first axis 510； and a second set of pulleys proximal to the first set and comprising a first pulley rotatable about a second axis and a second pulley rotatable about a third axis thats parallel to and offset from the second axis. The articulation further comprises a clevis 508 comprising two arms 530,531 supporting the pulley arrangement pulleys and a pulley guard 538,539 extending from one of the arms 530,531 for guarding one of the first and second pulleys. Clevis 508 may comprise first and second drive element guides 533,534 located between its first and second arms 530,531, where driving elements A1&A2 pass through first and second drive element guides 533,534 respectively.
