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Core
There are 27 bones in the hand, which all interact with each other to allow for complex movements in the hand. The bones of the hand are arranged much like those of the foot: a group of small bones at the wrist (the carpals, like the seven tarsals at the ankle), five long bones (the metacarpals, like the metatarsals that join the toes to the ankle bones) and the bones of the fingers and thumb (the phalanges, like the toe bones). The bones can be grouped into three categories:
- Carpals
- Metacarpals
- Phalanges
There are eight, irregularly shaped bones. Together they make up most of the skeletal framework of the wrist and allow it to move. When analysing the arrangement, the bones can be placed into rows:
In the proximal row, moving lateral to medial:
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
In the distal row, moving lateral to medial:
- Trapezium
- Trapezoid
- Capitate
- Hamate
The distal row of carpal bones articulates (forms joints) with the metacarpals. In the proximal row, the scaphoid and lunate articulate with the radius to form the wrist joint (the radiocarpal joint). The triquetrum also takes part in the wrist joint, but the pisiform does not. The ulna is kept apart from the carpal bones by the articular disc (a fibrocartilage ligament).
These bones can be difficult to remember. A mnemonic for the order above (proximal row first, then distal row, each lateral to medial) is: 'Some lovers try positions that they cannot handle'.
Like in the foot, where there are five metatarsals, there are five metacarpals in the hand; one for each digit. Each metacarpal has a base at its proximal end (nearest the wrist) and a head at its distal end (nearest the fingertip). The bases of the metacarpals articulate with the carpal bones, whilst the heads articulate with the proximal phalanges to form the metacarpophalangeal joints (where the fingers join the palm).
There are three phalanges in each digit (with the exception of the thumb, which only has two). These articulate with each other via interphalangeal joints (the joints between the finger bones), whilst the proximal phalanx articulates with its respective metacarpal via metacarpophalangeal joints.
Diagram - Illustrates the arrangement of bones in the left hand
Creative commons source by Mariana Ruiz Villarreal (LadyofHats) and Kolossos, edited by Dr. Sachin Sudhakaran [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
For Pathologies and Conditions of the Hand, check out our articles on Conditions of the Hand.
Reviewed by: Dr. Thomas Burnell and Dr. Marcus Judge
Edited by: Dr. Maddie Swannack
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