A surgical instrument that includes an instrument shaft having proximal and distal ends; a tool disposed from the distal end of the instrument shaft; a control handle coupled from the proximal end of the instrument shaft; a distal bendable member for coupling the distal end of the instrument shaft to the tool; a proximal bendable member for coupling the proximal end of the instrument shaft to the control handle; actuation means extending between the distal and proximal bendable members for coupling motion of the proximal bendable member to the distal bendable member for controlling the positioning of the tool and a locking mechanism for fixing the position of the tool at a selected position. The locking mechanism includes a ball and socket arrangement disposed about the proximal bendable member and a locking member for locking the ball and socket arrangement and having locked and unlocked states. The ball and socket arrangement includes a compression ring supported from the control handle, having an outer surface for support of the locking member thereabout and having an inner surface defining an at least partially spherical shaped socket. The ball and socket arrangement further includes a hollow ball member having an internal hollow chamber and an outer at least partially spherical shaped surface which mates with the at least partially spherical shaped socket.