What type of joint is the knuckle?

The knuckles of the hand are a type of condyloid joint. This type of joint allows flexion and extension. They also allow a limited amount of lateral deviation.

The joints between the metacarpal bones and the proximal phalanges of the hand are called the metacarpophalangeal joints. There are five of these joints in each hand. The joints between the proximal phalanges of the hand and the middle phalanges of the hand are called the proximal interphalangeal joints. The joints between the middle phalanges of the hand and the distal phalanges of the hand are called the distal interphalangeal joints of the hand.