Pivot joint in rotating an arm inward). When rotating the forearm, these movements are typically called pronation and supination. In the standard anatomical position, the forearms are supinated, which means that the palms are facing forward, and the thumbs are pointing away from the body. In contrast, a forearm in pronation would have the palm facing backward and the thumb would be closer to the body, pointing medially. Examples of a pivot joint include: In contrast, spherical joints (or ball and socket joints) such as the hip joint permit rotation and all other directional movement, while pivot joints only permit rotation. Pivot
Gliding flight Gliding flight Gliding flight is heavier-than-air flight without the use of thrust; the term volplaning also refers to this mode of flight in animals. It is employed by gliding animals and by aircraft such as gliders. This mode of flight involves flying a significant distance horizontally compared to its descent and therefore can be distinguished from a mostly straight downward descent like with a round parachute. Although the human application of gliding flight usually refers to aircraft designed for this purpose, most powered aircraft are capable of gliding without engine power. As with sustained flight, gliding generally requires the application