Bones of the hand

What are the bones of the hand?

The skeleton of the hand is built from 27 bones in three groups. From the wrist to the fingertips these are the carpals, the metacarpals and the phalanges. Together the two hands hold 54 bones, which is about a quarter of all the bones in the adult body.

So many small bones give the hand two qualities at once. It can grip with force, and it can make fine, precise movements such as writing or picking up a pin.

How are the hand bones grouped?

The carpal bones are eight small bones packed together at the wrist. The metacarpals are five long bones that fan out from the wrist to the knuckles and form the palm. The phalanges are the fourteen bones of the thumb and fingers.

Bones and digits are numbered from the thumb side. The thumb is the first digit and the little finger is the fifth. The first metacarpal therefore belongs to the thumb and the fifth to the little finger.

Which bones make up the wrist?

The eight carpals lie in two rows of four. The row next to the forearm holds the scaphoid, lunate, triquetrum and pisiform. The row next to the palm holds the trapezium, trapezoid, capitate and hamate.

The carpals are short, roughly cube-shaped bones. They glide a little on one another, and the sum of these small movements lets the wrist bend, straighten and tilt from side to side.

Which bones form the palm?

The palm is supported by five metacarpal bones. Each has a base at the wrist, a shaft, and a rounded head at the far end. The heads are the knuckles that stand out when the hand makes a fist.

The first metacarpal, at the base of the thumb, is the shortest and by far the most mobile. The other four are bound closely together and form a firm frame for the palm.

How many bones are in the fingers?

There are fourteen phalanges in each hand. Each of the four fingers has three: a proximal, a middle and a distal phalanx. The thumb has only two, a proximal and a distal.

The distal phalanges are the bones at the fingertips. Each ends in a flattened, roughened tip that supports the pulp of the finger and the nail.

How does the hand join the forearm?

The hand meets the forearm at the wrist joint, also called the radiocarpal joint. Here the broad lower end of the radius forms a shallow socket for the scaphoid and the lunate.

The ulna, the forearm bone on the little finger side, does not touch the carpals directly. A disc of cartilage lies between its head and the triquetrum. The model shows the bones only, so this appears as a gap.

What do the hand bones do?

The bones give the hand a frame that is both stable and adjustable. The carpals and the bases of the metacarpals form a curved arch across the wrist. The fingers can curl around an object of almost any shape.

The thumb is the key to the human grip. Its saddle-shaped joint with the trapezium lets it swing across the palm to meet each fingertip, a movement called opposition.

Common problems with the hand bones

A fall on an outstretched hand is the classic cause of wrist injuries. It can break the lower end of the radius or the scaphoid, the carpal most often fractured. A punch against a hard surface typically breaks the neck of the fifth metacarpal.

The small joints of the hand are also common sites of arthritis, especially the base of the thumb and the joints near the fingertips. This page describes anatomy only.

About this free 3D model of the bones of the hand

The interactive 3D model on this page is free to use in your browser, with no sign-up. It is built from scan-based anatomy data, so every bone is a separate, correctly placed shape you can turn and inspect from any side.