The 'GIF'ted Cellist
The animated GIF is great for focusing on the precise mechanism of the many formatted motions that we make when playing the cello. Here is a left-hand primer illustrated GIF-style.
The arm and hand work like a trap door, with the thumb as a hinge.
Notice how the full arm is involved in this motion, maintaining a simple flat wrist.
Individual finger motion will come later. For now just focus on the arm/hand's contribution to the opening and closing of the "trap door."
Think of it as checking your watch...
Again, notice the simple, flat wrist that allows the forearm and hand to work as one unit.
AVOID SINKING THE WRIST WHEN OPENING THE "TRAP DOOR!"
This is a common mistake that can lead to wrist pain, tendonitis, and carpal tunnel syndrome.
Here is the thumb - 2 motion.....