27 bones in one hand
Each of your hands has 27 bones. That's more than your whole arm and shoulder put together!
They come in three groups. Your wrist has 8 small bones. Your palm has 5 long bones. Your fingers and thumb have 14 bones.
Both hands together have 54 bones. That's about one quarter of all the bones in your body.
Wrist bones
Your wrist has 8 small bones in two rows of four. They are shaped like little pebbles and blocks. Their science name is carpals.
They slide and glide against each other. That lets your wrist bend up, down and side to side.
When a baby is born, these wrist bones are still mostly cartilage. They turn to bone one by one, over many years. Doctors can look at an X-ray of a kid's hand to see how much growing is left!
Palm and finger bones
Your palm has 5 long bones called metacarpals, one leading to each finger and your thumb. Make a fist: the big knuckles that pop up are the ends of these bones.
Your finger bones are called phalanges. Each finger has 3 of them. Your thumb has only 2.
Try it: bend your pointer finger and count its bends. There's one at the big knuckle and two more along the finger. Now bend your thumb. It bends in fewer places, because it has one fewer bone.
The amazing thumb
Your thumb sits a little apart from your fingers. It can swing across your palm to touch each fingertip. Try it: touch your thumb to each finger, one by one.
The joint at the bottom of your thumb, near your wrist, is shaped like a horse's saddle. It rocks two ways, which lets your thumb swing around.
That's what lets you pinch a tiny bead, hold a pencil and turn a key.
Why so many bones?
Lots of small bones means lots of joints. Each finger has three joints, and your wrist has many more. All those joints let your hand make all kinds of shapes.
Here's a surprise: there are no muscles inside your fingers. The muscles that bend them are in your palm and your forearm. They pull on long, strong cords called tendons, like the strings on a puppet.
Try it: hold your forearm with your other hand, then wiggle your fingers fast. Can you feel the muscles moving way up there?