The Hand Crew
Five metacarpals and the thumb's saddle
Clap your hands! The palm of each hand holds five long bones called metacarpals. Your knuckles are their round heads, and your thumb's one is special â it lets you pinch, grip, and hold a pencil.
The metacarpals of the hand
Real anatomy picture coming soon
Real anatomy photo spot: five metacarpals fanning out from the wrist to the knuckles
The fan
The five metacarpals fan out from your wrist to your knuckles like the struts of a fan. When you make a fist, you're curling bones at three places â the knuckle, the mid-palm joints, and the fingertips. Open and close your hand â the fan folds and unfolds!
The thumb's saddle
The base of your thumb sits on the trapezium bone, and the joint between them is shaped like a saddle â the only joint in your body that lets the thumb swing across the palm. That's why your thumb can pinch your fingers, hold a pencil, or turn a key.
Mr. Bones says: I'm a fictional skeleton, not a doctor! This is for learning and fun. If anything hurts, stop and tell a grown-up you trust.
