Region · Upper limb
Bones of the hand: carpals, metacarpals and phalanges
The hand and wrist have 27 bones in three groups, 8 carpals, 5 metacarpals and 14 phalanges. Learn their names, how they fit together and the muscles that attach to them.
The wrist and hand together have 27 bones: 8 carpal bones in the wrist, 5 metacarpal bones in the palm and 14 phalanges in the fingers and thumb. They are built on the same plan as the bones of the foot, but shaped for grip and fine movement instead of weight bearing.
At a glance
| Bone | Muscles that originate here | Muscles that insert here |
|---|---|---|
| Carpal bones | – | – |
| First metacarpal bone | Dorsal interossei muscles of hand | Abductor pollicis longus |
| Second metacarpal bone | Adductor pollicis, Dorsal interossei muscles of hand | Extensor carpi radialis longus, Flexor carpi radialis |
| Third metacarpal bone | Adductor pollicis, Dorsal interossei muscles of hand | Extensor carpi radialis brevis, Flexor carpi radialis |
| Fourth metacarpal bone | Dorsal interossei muscles of hand | – |
| Fifth metacarpal bone | Dorsal interossei muscles of hand | Extensor carpi ulnaris, Flexor carpi ulnaris |
| Proximal phalanx of thumb | – | Adductor pollicis, Extensor pollicis brevis |
| Distal phalanx of thumb | – | Extensor pollicis longus, Flexor pollicis longus |
| Proximal phalanx of index finger | – | – |
| Middle phalanx of index finger | – | – |
| Distal phalanx of index finger | – | Extensor indicis |
| Proximal phalanx of middle finger | – | – |
| Middle phalanx of middle finger | – | – |
| Distal phalanx of middle finger | – | – |
| Proximal phalanx of ring finger | – | – |
| Middle phalanx of ring finger | – | – |
| Distal phalanx of ring finger | – | – |
| Proximal phalanx of little finger | – | Abductor digiti minimi muscle of hand |
| Middle phalanx of little finger | – | – |
| Distal phalanx of little finger | – | – |
From the anatomical data behind Anatomy Atlas 3D (Z-Anatomy, CC BY-SA 4.0, reviewed). Names link to the detailed page when there is one.
How they are organized
Carpal bones
The eight carpals are small, irregular bones arranged in two rows of four. Named from the thumb side to the little-finger side:
- Proximal row: scaphoid, lunate, triquetrum and pisiform.
- Distal row: trapezium, trapezoid, capitate and hamate.
The scaphoid and lunate meet the radius at the wrist joint. The ulna does not touch the carpals directly: a disc of cartilage sits between them. The pisiform is a small pea-shaped bone inside the tendon of the flexor carpi ulnaris, so it is also a sesamoid bone. The capitate is the largest carpal, and the hamate has a hook you can feel at the base of the palm on the little-finger side.
In the app, the eight carpals are shown together as a single structure, "Carpal bones", so you can see the whole wrist block at once.
Metacarpal bones
The five metacarpals form the skeleton of the palm and are numbered I to V from the thumb. Each has a base (near the wrist), a shaft and a head; the heads are the knuckles you see when you make a fist. The first metacarpal, for the thumb, is the shortest and the most mobile.
Phalanges
The fingers have 14 phalanges. The thumb (the pollex) has two, proximal and distal. The index, middle, ring and little fingers each have three: proximal, middle and distal.
Sesamoid bones
Besides the pisiform, small sesamoid bones sit in the tendons at the base of the thumb in nearly everyone, and at other finger joints in some people. They are not counted among the 27, and their number varies.
What they do together
The carpals form an arch, hollow on the palm side. A strong band of tissue, the flexor retinaculum, spans this arch and turns it into the carpal tunnel, through which the median nerve and the long flexor tendons of the fingers and thumb pass into the hand.
The joints of the hand each have a clear role:
- The wrist joint, between the radius and the proximal row, bends the hand forward, back and side to side. The joints between the two carpal rows add to these movements.
- The carpometacarpal joint of the thumb, between the trapezium and the first metacarpal, is a saddle joint. It lets the thumb swing across the palm to touch each fingertip, a movement called opposition.
- The metacarpophalangeal joints, the knuckles, bend and straighten the fingers and let them spread apart.
- The interphalangeal joints are simple hinges: one in the thumb, two in each finger (proximal and distal).
The bones are only the frame. The muscles of the forearm send long tendons across the wrist to the phalanges, while small muscles inside the hand handle precision movements.
How to learn them
- Count 8, 5, 14 and check they make 27.
- Carpals with a mnemonic: "She Looks Too Pretty, Try To Catch Her". Scaphoid, Lunate, Triquetrum, Pisiform for the proximal row, then Trapezium, Trapezoid, Capitate, Hamate for the distal row, always from the thumb side.
- Trapezium or trapezoid? "The trapeziUM is by the thUMb": it carries the base of the thumb metacarpal. The trapezoid sits next to it, behind the index finger.
- Number from the thumb. Metacarpals and fingers are numbered 1 to 5 from the thumb.
- Feel them on your own hand. You can find the pisiform at the base of the palm on the little-finger side, the heads of the metacarpals as knuckles and the joint lines of each finger as skin creases.
Exams ask you to name the carpals in order, to place them on an X-ray-like diagram, or to name the bones that form the carpal tunnel. In the app, hide the muscle layers to see the bare skeleton of the hand, rotate it to compare the palm and back views, and quiz yourself on the upper limb by tapping each bone on the 3D body.
Frequently asked questions
How many bones are in the hand?
Twenty-seven counting the wrist: 8 carpals, 5 metacarpals and 14 phalanges. Sesamoid bones are usually not included.
What are the eight carpal bones?
Scaphoid, lunate, triquetrum and pisiform in the proximal row; trapezium, trapezoid, capitate and hamate in the distal row.
How many phalanges does the thumb have?
Two, a proximal and a distal phalanx. Each finger has three.
Which is the largest carpal bone?
The capitate, in the middle of the distal row.