Trigger Finger
Trigger finger limits finger movement. When you try to straighten your finger, it will lock or catch before popping out straight.
Trigger finger is a condition that affects the tendons in your fingers or thumb.
In this photo, the patient's finger sticks in the bent position as she tries to straighten it.
The tendon sheath attaches to the finger bones and keeps the flexor tendon in place as it moves.
Tendons are tissues that connect muscles to bone. When muscles contract, tendons pull on bones. This is what causes some parts of the body to move.
The muscles that move the fingers and thumb are located in the forearm, above the wrist. Long tendons — called the flexor tendons — extend from the muscles through the wrist and attach to the small bones of the fingers and thumb.
These flexor tendons control the movements of the fingers and thumb. When you bend or straighten your finger, the flexor tendon slides through a snug tunnel, called the tendon sheath, that keeps the tendon in place next to the bones.