The partial or complete entrapment of a tendon within its sheath. Often the index, or trigger, finger is affected due to squeezing a tool that causes pressure on the palm of the hand while there is stretching and pulling upon the tendon. The tendon and its sheath become inflamed. When repeated over time, changes to the tendon and sheath make it difficult for the tendon to move smoothly along its course. A popping or crackling sound can often be heard when the finger is re-extended.