Learning a little about hand anatomy is essential to understanding how the trigger finger occurs. To enable bending and straightening, your finger’s muscles and tendons cooperate. Strong bands of tissue known as pulleys, which are formed like arches over the tendon, keep the flexor tendons on the palm side of the hand in place. Your finger curls as you bend it because the fingers’ muscles tighten and pull on the tendons. The pulleys keep the tendons in place while the finger is curled to prevent the finger from snapping straight. However, when the tendon controlling the affected finger cannot move freely inside the tendon sheath surrounding it, a trigger finger occurs.