The bony basis is of eight small carpal bones in the wrist, five metacarpal bones in the fleshy part of the hand, and three phalanges in each finger – two only in the thumb. From the muscles of the forearm, 12 strong tendons run in front of the wrist. Of these, nine go to the fingers and thumb and are bound down by a strong band, the flexor retinaculum, in front of the wrist. They are each enclosed in a sheath, and pass through the palm and down the fingers. Behind the wrist, 12 tendons likewise cross from forearm to hand.

Forming the ball of the thumb and that of the little finger, and filling up the gaps between the metacarpal bones, are other muscles, which act to separate and bring together the fingers, and to bend them at their first joints (knuckles).

The bones of the right hand and wrist (palmar view). Bones marked ‘(c)’ form the carpal group of bones.