Trapezium
The trapezium (also known as the greater multangular) is one of the eight carpal bones of the hand. It is the most lateral (radial) bone of the distal row, located between the scaphoid and the first metacarpal bone. It articulates with the scaphoid proximally, the trapezoid medially, and the thumb and index metacarpals distally. The trapezium and trapezoid are collectively known as the multangulars.
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Gross anatomy
Osteology
The trapezium has six surfaces in total:
- rough palmar surface which contains a medial groove and prominent tubercle
- elongated rough dorsal surface
- large lateral surface
- concave medial surface
- large dorsolateral sellar surface (i.e. saddle-shaped) 3 which projects distally between the thumb and index metacarpals, and also has a small distomedial facet articulating with the index metacarpal base
- small concave proximal surface
Articulations
- articulates with the scaphoid at the midcarpal joint
- articulates with the trapezoid at its intercarpal joint
- articulates with the thumb metacarpal at the carpometacarpal joint of the thumb
Attachments
Musculotendinous
- superficial head of flexor pollicis brevis arises from the tubercle distally
- the opponens pollicis arises from the tubercle between flexor pollicis brevis and abductor pollicis brevis
- the abductor pollicis brevis arises from the tubercle proximally
Ligamentous
- two layers of the flexor retinaculum attach either side of the groove of the trapezium
- radial collateral ligament attaches to the lateral surface
- capsule of the carpometacarpal joint of the thumb attaches to the lateral surface
Relations
The tendon of flexor carpi radialis runs through the groove and the radial artery is directly related to the dorsal surface.
Arterial supply
Supplied by distal branches of the radial artery, primarily via the dorsal surface 2.
Venous supply
Drained by tributaries of the radial vein.
Radiographic features
Plain radiograph
The trapezium may be visualized on a number of series of the distal upper limb including:
Cross-sectional imaging
CT or MRI imaging will demonstrate the trapezium and should be considered if there is clinical suspicion of occult injury.
Development
Ossification
The trapezium begins to ossify in the fourth to fifth year.
Variant anatomy
Females have a significantly smaller sellar surface, with a fundamentally different shape of that surface 1.
History and etymology
Trapezium derives from the Ancient Greek: originally 'small table', later a four-sided figure with no parallel sides.
Related pathology
Related Radiopaedia articles
Anatomy: Upper limb
-
skeleton of the upper limb
- clavicle
- scapula
- humerus
- radius
- ulna
- carpal bones (mnemonic)
- metacarpals
- phalanges
- accessory ossicles of the upper limb
- accessory ossicles of the shoulder
- accessory ossicles of the elbow
-
accessory ossicles of the wrist (mnemonic)
- os centrale carpi
- os epilunate
- os epitriquetrum
- os styloideum
- os hamuli proprium
- lunula
- os triangulare
- trapezium secondarium
- os paratrapezium
- os radiostyloideum (persistent radial styloid)
- joints of the upper limb
-
pectoral girdle
-
shoulder joint
- articulations
- associated structures
- joint capsule
- bursae
- ligaments
-
movements
- scapulothoracic joint
- glenohumeral joint
- arm flexion
- arm extension
- arm abduction
- arm adduction
- arm internal rotation (medial rotation)
- arm external rotation (lateral rotation)
- circumduction
- blood supply - scapular anastomosis
- ossification centers
-
shoulder joint
-
elbow joint
- proximal radioulnar joint
- ligaments
- associated structures
- movements
- alignment
- blood supply - elbow anastomosis
- development
-
wrist joint
- articulations
-
ligaments
- intrinsic ligaments
- extrinsic ligaments
- radioscaphoid ligament
- dorsal intercarpal ligament
- dorsal radiotriquetral ligament
- dorsal radioulnar ligament
- volar radioulnar ligament
- radioscaphocapitate ligament
- long radiolunate ligament
- Vickers ligament
- short radiolunate ligament
- ulnolunate ligament
- ulnotriquetral ligament
- ulnocapitate ligament
- ulnar collateral ligament
- associated structures
- extensor retinaculum
- flexor retinaculum
- joint capsule
- movements
- alignment
- ossification centers
-
hand joints
- articulations
- carpometacarpal joint
-
metacarpophalangeal joints
- palmar ligament (plate)
- collateral ligament
-
interphalangeal joints
- palmar ligament (plate)
- collateral ligament
- movements
- ossification centers
- articulations
-
pectoral girdle
- spaces of the upper limb
- muscles of the upper limb
- shoulder girdle
- anterior compartment of the arm
- posterior compartment of the arm
- anterior compartment of the forearm
-
posterior compartment of the forearm (extensors)
- superficial
- deep
- hand (mnemonic)
- accessory muscles
- blood supply to the upper limb
-
arteries
- subclavian artery (mnemonic)
- axillary artery
- brachial artery (proximal portion)
- ulnar artery
- radial artery
- veins
-
arteries
- innervation of the upper limb
- intercostobrachial nerve
-
brachial plexus (mnemonic)
- branches from the roots
- branches from the trunks
- branches from the cords
- lateral cord
- posterior cord
- medial cord
- terminal branches
- lymphatic drainage of the upper limb