Trapezoid

Original Editor

Top Contributors - Nina Myburg and Kim Jackson

Description

The trapezoid bone is one of eight carpal bones that forms part of the wrist joint. The word trapezoid is derived from the Greek word trapezion which means “a little table” of “irregular quadrilateral”.[1] It is a wedge-shaped carpal bone that resembles the trapezium.[2] It is also called the lesser multangular bone.

Trapezoid bone (left hand)

Structure

The trapezoid is situated in the distal row of carpal bones and is the smallest of these bones. It is wedge-shaped with four articular facets. 

Function

The trapezoid, together with the other carpal bones give bony structure to the wrist and hand. Being part of the distal row of carpal bones, it gives structure to specifically the palm of the hand.[2]

Articulations

The trapezoid articulates with four bones. Proximally it articulates with the scaphoid, distally the second metacarpal, laterally with the trapezium and medially with the capitate.[1] 

Muscle attachments

There are no muscle attachments onto the trapezoid. However, there are ligaments that attach to this bone. Interosseus ligaments between the trapezoid and the trapezium, capitate and scaphoid respectively. Due to these ligaments and its position in the distal row of carpal bones, it is fairly protected from injury.[1] 

References

  1. 1.0 1.1 1.2 Gray H. Anatomy of the Human Body. Twentieth edition. Philadelphia: Lea & Febiger; 1918 Available from: https://www.bartleby.com/107/54.html [Accessed 19 June 2019]
  2. 2.0 2.1 Moore KL, Dalley AF. Clinically Oriented Anatomy. Fifth edition. Philadelphia: Lippincot Williams & Wilkins; 2006