Joint · Hand

Distal interphalangeal joints (hand)

The last joint of each finger, between the middle bone and the one carrying the nail — the joint that makes a fingertip curl over. It is a pure hinge: the head of the middle phalanx is a two-lobed pulley sitting in a matching double hollow on the base of the bone beyond it, so the joint bends and straightens and does nothing else at all. There are four of them; the thumb has a single interphalangeal joint of the same design instead. It is the smallest working joint in the hand and the one that does the last few degrees of conforming when you close your hand around something irregular.