The ring finger is shorter than the middle finger in extension and longer in flexion. This is pronounced when the proximal interphalangeal joint is fully flexed and the distal interphalangeal joint is fully extended. As the player strongly grabs the jersey (or pants) of an opposing runner, the ring finger is the first to be hooked and last to be released from the jersey. The tip of the ring finger then bears the full brunt of body pull causing the flexor digitorum profundus tendon to avulse from the distal phalanx. 75% of avulsions affect the ring finger. Why the fourth finger is longer in flexion has not been previously explained. Kinematics of the carpometacarpal joints may explain why the ring finger is longer in flexion than extension. This study correlates the linear displacement of the tip of the ring finger in the palm in relation to the angular displacement of the ring carpometacarpal joint. Material and methods: One hundred normal hands of twenty five male and twenty five female volunteers were studied by two independent study groups. The position of the tip of the ring finger was marked on the palm with proximal interphalangeal joint in full flexion and distal interphalangeal joint in neutral. The distance between the tips of the ring and middle fingers was noted. The ring finger metacarpal head was dorsally pushed with a mallet shaped device. Maximal force was applied that was comfortably tolerated by the subject. The position of the tip of the ring finger was noted again. Results: Since the carpometacarpal joints of the ring (and small) fingers are mobile and the carpometacarpal joints of the middle (and index) fingers are fixed, carpometacarpal joint of ring finger flexes when a fist is made while the carpometacarpal joints of the adjacent middle finger remains stable. In fist position, if the carpometacarpal joint of the ring finger is manually extended by applying dorsally directed pressure on the metacarpal head in the palm, the ring finger appears shorter than the middle finger. The relation between angular displacement of ring carpometacarpal joint and linear displacement of the tip of the ring finger is always positive. Linear displacement at the ring finger tip occurs directly in proportion to flexion at the carpometacarpal joint of the ring metacarpal. Conclusion: More the flexion at carpometacarpal joint, longer is the ring finger in flexion.