Os trapezium

Os Trapezium

The os trapezium is one of the eight carpal bones in the human hand. It is situated in the first row of the carpus, between the scaphoid bone and the first metacarpal bone. The os trapezium is distinguished by a deep groove on its anterior surface. It is the bone that is most radial in the distal row of carpal bones.

Structure

The os trapezium is irregular in shape, but four-sided, and therefore, it is named after the geometric figure, the trapezium. It is characterized by a deep groove, known as the trapezium groove, on its anterior surface. This groove is directed forward, laterally, and downward, and transmits the tendon of the Flexor carpi radialis muscle.

Function

The os trapezium, along with the other carpal bones, contributes to the flexibility of the wrist. It also forms the radial border of the carpal tunnel, which is a passageway in the wrist through which nerves and tendons pass. The os trapezium articulates with the first metacarpal bone, forming the carpometacarpal joint of the thumb, which allows for the thumb's wide range of motion.

Clinical significance

Injuries to the os trapezium are relatively rare due to its protected position in the wrist. However, fractures can occur, often as a result of a fall onto an outstretched hand. Such injuries can lead to complications such as carpal instability and osteoarthritis. Treatment typically involves immobilization of the wrist, but in severe cases, surgery may be required.

See also

• Carpal bones
• Carpal tunnel
• Carpometacarpal joint