Pivot Joint

A pivot joint is an articulation within a ligamentous ring between the rounded end of one bone and another bone. This type of joint is uniaxial because, although the bone rotates within this ring, it does so around a single axis. An example would be the atlantoaxial joint between C1 (atlas) and C2 (axis) of the vertebrae, permitting side-to-side head motion. Another example is the proximal radioulnar joint. The radius sits in the annular radial ligament, which holds it in place as it articulates with the radial notch of the ulna, which permits pronation and supination.