Left hand anterior view (palmar view). Trapezium shown in red.
The left trapezium bone
|Latin||Os trapezium, os multangulum majus|
1st metacarpal distally
2nd metacarpal medially
|Anatomical terms of bone|
- Surfaces 1.1
- Tubercle of trapezium 1.2
- Function 2
- Clinical relevance 3
- History 4
- Additional images 5
- See also 6
- References 7
The trapezium is distinguished by a deep groove on its anterior surface. It is situated at the radial side of the carpus, between the scaphoid and the first metacarpal bone (the metacarpal bone of the thumb). It is homologous with the first distal carpal of reptiles and amphibians.
The trapezium is an irregularly-shaped carpal bone found within the hand. The trapezium is found within the distal row of carpal bones, and is directly adjacent to the metacarpal bone of the thumb. On its ulnar surface are found the trapezoid and scaphoid bones.:708
The inferior surface is oval, concave from side to side, convex from before backward, so as to form a saddle-shaped surface for articulation with the base of the first metacarpal bone. This saddle-shaped articulation is partially responsible for the Carpometacarpal joint#Thumb's opposable motion.
The dorsal surface is smooth.
The palmar surface is narrow and rough. At its upper part is a deep groove, running from above obliquely downward and medialward; it transmits the tendon of the Flexor carpi radialis, and is bounded laterally by an oblique ridge. This surface gives origin to the Opponens pollicis and to the Abductor and Flexor pollicis brevis; it also affords attachment to the transverse carpal ligament.
The lateral surface is broad and rough, for the attachment of ligaments.
Tubercle of trapezium
The carpal bones function as a unit to provide a bony superstructure for the hand. The trapezium is the most radial of the bones surrounding the carpal tunnel.:708 It is important in thumb movement.
The trapezium is susceptible to arthritis at the joint with the metacarpal bone of the thumb, due to overuse.
The etymology derives from the Greek trapezion which means "a little table", from trapeza meaning "table", itself from (te)tra- "four" and pod- "foot". The bone was first documented in 1840.
- Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone.
- Eathorne, SW (Mar 2005). "The wrist: clinical anatomy and physical examination--an update.". Primary care 32 (1): 17–33.
- Harper, Douglas. "Trapezium". Online Etymology Dictionary. Retrieved 5 January 2014.