A tool having a wrist mechanism that provides pitch and yaw rotation in such a way that the tool has no singularity in roll, pitch, and yaw. In one embodiment, a minimally invasive surgical instrument comprises an elongate shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end； and an end effector. A wrist member has a flexible tube including an axis extending through an interior surrounded by a wall. The wall of the flexible tube includes a plurality of lumens through which actuation cables extend, the lumens oriented generally parallel to the axis of the flexible tube. The wrist member has a proximal portion connected to the working end of the elongate shaft and a distal portion connected to the end effector.
