Unlike most fingers, the thumb can move across the palm and oppose the other fingers.
This ability is called opposition.
It allows you to perform tasks such as:
- Holding a cup
- Turning a key
- Opening a jar
- Using scissors
- Buttoning clothing
- Writing
- Using a smartphone
- Picking up small objects
- Gripping tools
Much of this ability comes from the unique structure of the thumb and the joints that connect its bones.
The thumb contains two main phalanges—the proximal and distal phalanges—connected by the interphalangeal joint.
It also connects to the hand through the metacarpophalangeal joint and the thumb’s carpometacarpal joint.
The shape and movement of these joints contribute significantly to the appearance of your thumb.
Why Do Some Thumbs Bend Backward?
One of the most noticeable differences in the image is thumb flexibility.
Some people’s thumbs can bend backward farther than others.
This can be a normal variation in joint mobility.
