Carpometacarpal joints

The joints that connect the carpal bones of the wrist to the metacarpal bones of the hand.

Carpometacarpal joints (CMC joints) are synovial joints located at the base of each finger and the thumb, linking the distal carpal bones to the proximal ends of the metacarpal bones. These joints enable a variety of thumb and finger movements, allowing for greater dexterity and function in the hand.

Terminologia Anatomica

articulatio carpometacarpalis

System

Skeletal system

Function

The carpometacarpal joints play a crucial role in hand functionality, particularly in grasping, pinching, and manipulating objects. Each joint contributes to the overall mobility and strength of the hand. The CMC joint of the thumb, in particular, is unique because it is a saddle joint, allowing for a wide range of motion, including opposition, which is essential for gripping and using tools. This versatility facilitates intricate tasks, such as writing or playing musical instruments. The stability and biomechanics of the CMC joints are vital for activities that require fine motor skills, making them essential for everyday functioning.

Location

The carpometacarpal joints are situated at the junction where the carpal bones of the wrist meet the metacarpal bones of the hand. Specifically, the first CMC joint is located at the base of the thumb, connecting the trapezium carpal bone with the first metacarpal. The other four CMC joints, connecting the second to the fifth metacarpal bones to the trapezoid, capitate, and hamate carpal bones, are arranged in a somewhat linear fashion, following the skeletal structure of the hand. This anatomical arrangement allows for a balance of stability and flexibility.

Did You Know?

The carpometacarpal joint of the thumb is the most mobile joint in the hand, allowing for a thumb opposition that is crucial for grasping.
In humans, the design of the carpometacarpal joints aids in the evolution of tool use by providing increased dexterity and grip strength.
Injury or arthritis in the CMC joints, especially the thumb, can severely impact daily activities, leading to significant pain and loss of function.