Pivot joint Pivot joint In animal anatomy, a pivot joint (trochoid joint, rotary joint, lateral ginglymus) is a type of synovial joint. In pivot joints, the axis of a convex articular surface is parallel with the longitudinal axis of the bone. According to one classification system, a pivot joint like the other synovial joint —the hinge joint has one degree of freedom. Note that the degrees of freedom of a joint is not the same as the same as joint's range of motion. Pivot joints allow for rotation, which can be external (for example when rotating an arm outward), or internal (as
Pivot gun be used in fixed positions such as in a fort or on a battleship. There was no standard size of pivot gun, though they tended to be fairly substantial weapons. Like other cannons, they were muzzleloaders and could fire either shells or grapeshot (or other types of shot). Their calibers ranged from a few inches to the giant 11-inch Dahlgren guns used by the United States Navy in the mid-19th century. Pivot guns had a major disadvantage in warfare: they were very difficult to protect in battle and were necessarily very exposed, as they lay close to the surface of