The metacarpals are the five long hand bones between your wrist and fingers. They make up the palm of your hand and are visible through the skin on the back of your hand. Each metacarpal bone corresponds to a digit (finger) and consists of a base, shaft or body, and head.
Slightly thicker and shorter, the first metacarpal has the most mobility and can move on its own. The second through fifth metacarpals move alongside each other and are similar in size and shape. Of these four bones, the fourth and fifth are the most mobile.
The five metacarpal bones are:
First (thumb) metacarpal: thickest, shortest metacarpal bone, moves along with with the trapeziumSecond (index) metacarpal: longest metacarpal bone with the largest base that connects to the trapezium, trapezoid, and capitateThird (middle) metacarpal: articulates with the capitateFourth (ring) metacarpal: articulates with the capitate and hamateFifth (pinky) metacarpal: smallest metacarpal bone, articulates with the hamate