rotation /rōtā″shən/ [L, rotare] , 1. the gyration of a bone around its central axis, one of the four basic movements allowed by the various joints of the skeleton. The central axis may lie in a separate bone, as in the pivot formed by the dens of the axis around which the atlas turns. Some bones, such as the humerus, rotate around their own longitudinal axis. Alternatively, the axis of rotation may not be quite parallel to the long axis of the rotating bone, as in movement of the radius on the ulna during pronation and supination of the hand. Compare angular movement, circumduction, gliding. 2. a turning around an axis. 3. the turning of the fetal head to descend through the pelvis during birth. 4. a clinical experience in hospitals and clinics for students in the health professions, designed as an integral component of the curriculum.
