Note: Moving the Spline IK helpers to curl the spline can sometimes cause bones to rotate or flip unexpectedly. If this happens, you can try choosing a different upnode object with the IK chain's Pick Upnode option in the IK Solver Properties rollout (see Spline IK Solver Rollouts), or use a different IK method for your…
@snake85027 It's a bug in 3ds Max, a super old bug. You can adjust the Spline IK upnode all you want, but you'll get nothing good. Notice the flipping on the right tentacle. (The upnodes are in the center.) The work around is to use Spline IK on a duplicate bone chain (Chain B ) exactly how you set it up in your…