To better understand trigger finger, it helps to understand the anatomy of the finger.

Tendons are strong bands of tissue that connect muscle to bone. Each muscle has two tendons, each of which attach to a bone. The bones come together to form a joint. When a muscle contracts, the tendons pull on the bones, resulting in movement of the joint.

The tendons in the fingers pass through ligaments, which act as pulleys.

The ligaments keep the tendons in place as the fingers move.