The carpometacarpal joint is a type of joint located in the hand, specifically where the carpal bones meet the metacarpal bones. This joint allows for a range of movements, including flexion, extension, abduction, and adduction, which are essential for hand function. The most notable carpometacarpal joint is the one at the base of the thumb, known as the first carpometacarpal joint. This joint is a saddle joint, allowing for greater mobility compared to other carpometacarpal joints, which are primarily plane joints. This unique structure enables the thumb to perform its crucial role in grasping and pinching.