Metacarpals

The metacarpals are the five long bones of the palm, one for each finger and thumb. Each has a base at the wrist, a shaft, and a rounded head that forms a knuckle. The thumb's metacarpal is shorter, stouter and rotated, while the four finger metacarpals are bound together by ligaments into the palm's framework; the outer ones (thumb and little finger sides) move more, cupping the palm for grip.

Key facts

There are five metacarpals, numbered 1 (thumb) to 5 (little finger).
Their heads form the knuckles of a clenched fist.
The palm's deep muscles (interossei and lumbricals) attach between them.
The 4th and 5th metacarpals move slightly, letting the palm cup.
The 2nd and 3rd form the hand's rigid central column.

What can go wrong

Metacarpals are frequently fractured — the neck of the little-finger metacarpal in the classic 'boxer's fracture' from punching. Most heal with splinting if the finger still aligns and rotates correctly; displaced, rotated or open fractures may need pinning or plating. Arthritis at the thumb base involves the first metacarpal's joint with the trapezium.

Related procedures & tests

Related symptoms

Wrist pain

Related muscles

Frequently asked questions

What is a boxer's fracture?

A break of the neck of the fifth metacarpal — the little finger's palm bone — usually from a clenched fist striking a hard object. Despite the name, it happens more often in fights and falls than in boxing.

Why do doctors check finger rotation after a hand fracture?

If a metacarpal heals even slightly rotated, the finger will cross over its neighbour when making a fist. Alignment is judged by watching all the fingertips point towards the same spot at the wrist.

Educational information only. This atlas explains normal anatomy and describes conditions in general terms; it is not medical advice and does not replace assessment by a qualified clinician. If you have symptoms that worry you, seek medical care.