What bones meet to form a pivot joint?

A pivot joint is formed by the articulation of two bones, typically where one bone rotates around another. The classic example is the atlantoaxial joint in the neck, where the atlas (the first cervical vertebra) meets the axis (the second cervical vertebra), allowing for the rotation of the head. Another example is the proximal radioulnar joint, where the radius and ulna in the forearm allow for rotational movement.