Joints are cartilage surfaces that connect bones to each other. This cartilage allows our bones to glide smoothly against one another, allowing us painless movement. There are four joints in each finger, totaling 20 joints in each hand!
The small, ringer, middle and index fingers all have the same four joints:
- Distal Interphalangeal Joint (DIP): The DIP joint is located at the tip of the finger, just before the finger nail starts. Arthritis can develop at this joint, and it is also commonly fractured.
- Proximal Interphalangeal Joint (PIP): The PIP joint is the joint just below the DIP joint. It is located below the top two bones of the finger and allows the finger to bend and extend. This joint can become stiff easily after injury.
- Metacarpophalangeal Joint (MCP): The MP joint is where the hand bone meets the finger bone, referred to as the “knuckle.” These joints are very important, allowing us to bend/flex and spread our fingers.
- Carpometacarpal Joint (CMC Joint): The CMC joint is located at the bottom of the hand bone. This joint varies in each finger. For example, in the index finger, it has little motion. In the small finger, it has a lot of motion. Injuries and problems with this joint are uncommon.
The thumb joints are a little different than the other finger joints. To learn more about the thumb joints and more about the finger joints, visit our online Anatomy section.