What type of movement is described by the term "rotation"?

The term "rotation" refers to a type of movement in which an object, such as a limb or the head, turns around an axis. This is best illustrated by the action of turning your head from side to side. In this scenario, the head pivots on the neck, allowing it to rotate about the vertical axis.

This pivot movement is fundamental to understanding joint mechanics, especially in ball-and-socket joints like the shoulder and hip, where rotation allows for a wider range of motion. The other options describe different types of movements: bending or folding (flexion); movement away from the midline (abduction); and opening a joint (extension or dislocation), which do not encompass the idea of turning around an axis. Thus, the correct choice accurately reflects the definition of rotation as a specific type of pivot movement.