Trapezium (bone)

The trapezium (also known as the greater multangular bone) is one of the eight carpal bones of the wrist. It is situated in the distal row of carpal bones and is the most lateral bone in this row. The trapezium is distinguished by its saddle-shaped articular surface, which articulates with the base of the first metacarpal bone (thumb), allowing for the wide range of motion of the thumb.

Anatomy

The trapezium is a small, irregularly shaped bone with several distinct surfaces:

• The superior surface articulates with the scaphoid bone.
• The inferior surface articulates with the base of the first metacarpal bone.
• The medial surface articulates with the trapezoid bone and the base of the second metacarpal bone.
• The lateral surface is rough and non-articular.

Articulations

The trapezium articulates with four bones:

• Scaphoid bone (proximally)
• First metacarpal bone (distally)
• Second metacarpal bone (medially)
• Trapezoid bone (medially)

Function

The trapezium plays a crucial role in the mobility and stability of the thumb. Its saddle-shaped joint with the first metacarpal bone forms the carpometacarpal joint of the thumb, which is a biaxial joint allowing for flexion, extension, abduction, adduction, and opposition of the thumb. This joint is essential for the thumb's wide range of motion and its ability to grasp and manipulate objects.

Clinical significance

Injuries or conditions affecting the trapezium can significantly impair thumb function. Common issues include:

• Osteoarthritis of the carpometacarpal joint, which can cause pain and reduced mobility.
• Fractures of the trapezium, which may occur due to falls or direct trauma to the wrist.

See also

• Carpal bones
• Hand
• Wrist
• Scaphoid bone
• Trapezoid bone
• First metacarpal bone