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Human Anatomy · Structure

Carpal Bones Diagram

The eight carpal bones of the wrist in two rows, with the radius, ulna and metacarpals, the mnemonic and the carpal tunnel.

The right wrist seen from the palm, thumb to the right: the radius and ulna below, the eight carpal bones in two rows of four, and the bases of the five metacarpals above. The dashed band is the flexor retinaculum, the roof of the carpal tunnel. Press any bone for its shape, its neighbours and its clinical point, or take the tour, which starts with the mnemonic. Not to scale.

Also called Wrist bones, Bones of the wrist or Carpal bones mnemonic.

A labelled line drawing of the right wrist from the palm, thumb to the right. At the bottom are the cut ends of the radius, on the thumb side, and the ulna, which stops short of the carpals with the triangular fibrocartilage complex between its head and the carpals. Above them lies the proximal row, from the thumb side: scaphoid, lunate, triquetrum, with the small round pisiform sitting on the triquetrum. Above that lies the distal row: trapezium, trapezoid, capitate and hamate, with the hook of the hamate drawn as an oval on its palmar face. The bases of the five metacarpals stand along the top, the thumb's leaning out to the right. A dashed band, the flexor retinaculum, crosses the carpus from the trapezium and scaphoid to the hook of the hamate and the pisiform.TrapezoidMetacarpal of the thumbTrapeziumScaphoidFlexor retinaculum (dashed)RadiusCapitateMetacarpalsHamateHook of hamateLunateTriquetrumPisiformTriangular fibrocartilagecomplex (TFCC)Ulna
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Press any part of the diagram, or pick one here, to see what it is and what it does.

Download the diagramChecked against its sources on 5 November 2026.

A tour

A tour of the carpal bones

  1. 01The wrist at a glance

    Eight carpal bones link the forearm to the hand, between the radius and ulna below and the bases of the five metacarpals above. They lie in two rows of four: a proximal row that meets the radius, and a distal row that is bound to the metacarpals. This is the right wrist seen from the palm, so the thumb is on the right.

  2. 02Naming the eight: Some Lovers Try Positions That They Cannot Handle

    Read from the thumb side to the little finger, the proximal row is Scaphoid, Lunate, Triquetrum, Pisiform, and the distal row is Trapezium, Trapezoid, Capitate, Hamate. The mnemonic gives their first letters in that order: Some Lovers Try Positions That They Cannot Handle. In the drawing it runs right to left along each row, because the thumb is on the right.

  3. 03The radiocarpal joint: the radius, not the ulna

    The wrist joint is the radiocarpal joint, a condyloid synovial joint. The scaphoid and lunate rest on the distal end of the radius. The ulna does not reach the carpals: between its head and the lunate and triquetrum lies the triangular fibrocartilage complex, which stabilises the distal radioulnar joint. About 35 percent of the load across the wrist passes through the radiolunate joint, and 10 to 20 percent (estimates differ) through the fibrocartilage to the ulna.

  4. 04The midcarpal joint: two rows that move differently

    Between the rows lies the midcarpal joint. The four distal bones are bound to each other and to the metacarpal bases by strong ligaments and move as one unit. No tendon attaches to the scaphoid, lunate or triquetrum: the proximal row is an intercalated segment, moved only by the bones and ligaments around it, and it provides most of the wrist's motion. The scapholunate and lunotriquetral ligaments hold its three bones together.

  5. 05The carpal tunnel

    In the palm the carpals form an arch roofed by the flexor retinaculum, from the scaphoid and trapezium across to the pisiform and hook of hamate. Through this carpal tunnel pass the median nerve and nine tendons: the eight long finger flexors and flexor pollicis longus. Raised pressure squeezes the median nerve: carpal tunnel syndrome, with pain, numbness and tingling in the thumb, index and middle fingers and half the ring finger, worst at night, and later thenar wasting.

  6. 06The scaphoid: the fracture that must not be missed

    The scaphoid is the most often fractured carpal, usually after a fall on the outstretched hand. Pressing the anatomical snuffbox hurts in nearly every case, though the first radiographs often show nothing. Its blood supply enters at the distal end and runs back through the bone, so a waist or proximal pole fracture can starve the proximal pole, which may die (avascular necrosis) or fail to unite; untreated non-union brings arthritis within a few years.

  7. 07The lunate: Kienböck disease and perilunate dislocation

    The lunate is the central bone of the proximal row, resting on the radius and cupping the capitate. Kienböck disease is avascular necrosis of the lunate, first described in 1910. In a perilunate dislocation, a high-energy injury with the wrist forced into extension, the capitate and the rest of the carpus are driven out of place around the lunate, or the lunate itself is forced out; up to a quarter are missed at first, and the median nerve can be damaged.

  8. 08The little-finger side: triquetrum, pisiform and the hook of hamate

    The triquetrum is the second most often fractured carpal, usually a small dorsal chip treated with a splint or cast. The pisiform is a sesamoid bone within the flexor carpi ulnaris tendon, and its rare dislocation is easily taken for a sprain. The hook of the hamate breaks under repeated impact in tennis, baseball and golf; a missed fracture can leave chronic pain, non-union, irritation of the ulnar nerve beside it and rupture of the flexor tendons that run over it.

  9. 09Ossification: capitate first, pisiform last

    The carpals are still cartilage at birth and ossify one by one through childhood, which is why a hand radiograph is used to read a child's bone age. The capitate and hamate ossify in the first year, the triquetrum in about the third, the lunate in the fourth, the scaphoid in the fifth, the trapezium and trapezoid in about the sixth, and the pisiform last, between about the ninth and twelfth year. Girls run ahead of boys, and the exact ages vary between populations.

Parts

What each part of the carpal bones does

Scaphoid
The boat-shaped bone on the thumb side of the proximal row, tilted so that its proximal pole rests on the radius and its distal pole reaches the trapezium and trapezoid; it also meets the lunate and capitate. The most often fractured carpal bone, usually across its waist, with tenderness in the anatomical snuffbox.
Lunate
The central bone of the proximal row, resting on the radius and cupping the head of the capitate; it meets the scaphoid, triquetrum and capitate, and the ulna only through the triangular fibrocartilage. Kienböck disease is avascular necrosis of the lunate.
Triquetrum
The pyramid-shaped bone on the little-finger side of the proximal row, almost entirely covered in cartilage. It meets the lunate, the hamate and, on its palmar face, the pisiform, and rests on the triangular fibrocartilage. After the scaphoid it is the most often fractured carpal, usually a small dorsal chip.
Pisiform
A small sesamoid bone that sits within the tendon of flexor carpi ulnaris on the palmar face of the triquetrum, the only carpal it touches. Its dislocation is rare and easily taken for a sprain.
Trapezium
The bone on the thumb side of the distal row, under the thumb. Its joint with the first metacarpal is inherently mobile, and a Bennett fracture at the base of the first metacarpal makes it unstable. Trapezium fractures are about 3.5 percent of carpal fractures.
Trapezoid
The small wedge-shaped bone between the trapezium and the capitate, under the base of the second metacarpal, in a stable, protected position. The least often fractured carpal, about 0.4 percent of carpal fractures, usually from force driven down the second metacarpal.
Capitate
The central bone of the distal row, well protected: its rounded head sits in the cup made by the scaphoid and lunate, with the trapezoid on one side and the hamate on the other. About 1 to 11 percent of carpal fractures in different series, most often together with a scaphoid fracture or a perilunate injury.
Hamate
The triangular bone on the little-finger side of the distal row: it meets the capitate on the thumb side, the triquetrum below, and the fourth and fifth metacarpals above. Its fractures are rare and easily missed, and are grouped as hook fractures and body fractures.
Hook of hamate
A bony process on the palmar face of the hamate and, with the pisiform, a medial anchor of the flexor retinaculum. It breaks under repeated impact in tennis, baseball and golf, giving grip weakness and pain on the little-finger side of the wrist; the ulnar nerve and artery run beside it.
Radius
The forearm bone on the thumb side. The scaphoid and lunate rest on its distal end, and about 35 percent of the load across the wrist passes through the radiolunate joint alone.
Ulna
The forearm bone on the little-finger side. Its head does not reach the carpals: the triangular fibrocartilage complex lies between it and the lunate and triquetrum, so only about 10 to 20 percent of the load across the wrist, by different estimates, reaches the ulna.
Triangular fibrocartilage complex (TFCC)
A load-bearing disc of fibrocartilage and ligaments between the head of the ulna and the lunate and triquetrum. It is the main stabiliser of the distal radioulnar joint and a common cause of pain on the little-finger side of the wrist.
Metacarpals
The five bones of the palm, whose bases sit on the distal row: the thumb's on the trapezium, the second's, the largest base, on the trapezium, trapezoid and capitate, the third's on the capitate, the fourth and fifth on the hamate. The distal row is bound so tightly to them that the two move as one unit.
Flexor retinaculum
A fibrous band, also called the transverse carpal ligament, that roofs the carpal tunnel: it spans the carpus from the scaphoid and trapezium on the thumb side to the pisiform and the hook of the hamate. The median nerve and nine flexor tendons pass beneath it.

As a table

The carpal bones as a table

The eight carpal bones: their row, their place from the thumb side, the bones they articulate with, and the clinical point worth knowing for each.

  • Scaphoid

    Row
    Proximal
    Position (thumb to little finger)
    1st
    Articulates with
    Radius, lunate, capitate, trapezium, trapezoid
    Clinical note
    Most often fractured carpal (2 to 7% of all fractures); snuffbox tenderness; proximal pole at risk of avascular necrosis and non-union

  • Lunate

    Row
    Proximal
    Position (thumb to little finger)
    2nd
    Articulates with
    Radius, scaphoid, triquetrum, capitate (sometimes hamate); ulna through the TFCC
    Clinical note
    Kienböck disease (avascular necrosis); perilunate dislocation

  • Triquetrum

    Row
    Proximal
    Position (thumb to little finger)
    3rd
    Articulates with
    TFCC, lunate, hamate, pisiform
    Clinical note
    Second most often fractured carpal, usually a dorsal chip

  • Pisiform

    Row
    Proximal
    Position (thumb to little finger)
    4th
    Articulates with
    Triquetrum
    Clinical note
    A sesamoid in the flexor carpi ulnaris tendon; dislocation is rare and easily missed

  • Trapezium

    Row
    Distal
    Position (thumb to little finger)
    1st
    Articulates with
    Scaphoid, trapezoid, first and second metacarpals
    Clinical note
    Mobile joint with the thumb's metacarpal; Bennett fracture at the first metacarpal base; 3.5% of carpal fractures

  • Trapezoid

    Row
    Distal
    Position (thumb to little finger)
    2nd
    Articulates with
    Scaphoid, trapezium, capitate, second metacarpal
    Clinical note
    Least often fractured carpal (about 0.4%); wedge shape, may dislocate dorsally

  • Capitate

    Row
    Distal
    Position (thumb to little finger)
    3rd
    Articulates with
    Scaphoid, lunate, trapezoid, hamate, and the metacarpal bases, chiefly the third
    Clinical note
    Central and protected; a few percent of carpal fractures (about 1 to 11% across series), often with the scaphoid or a perilunate injury

  • Hamate

    Row
    Distal
    Position (thumb to little finger)
    4th
    Articulates with
    Capitate, triquetrum, fourth and fifth metacarpals
    Clinical note
    Hook fracture in golfers, batters and tennis players; ulnar nerve beside the hook

Fracture shares are from single-centre series and vary between studies; one recent series found the triquetrum fractured more often than the scaphoid. Ossification ages are typical, not exact.

Dictionary

The terms to know

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Sources

Where the facts come from

Drawn and written by biofideX from these sources.

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