The Colles fracture describes a fracture of the distal radius; it is commonly caused by falling on an outstretched arm. A fracture of the ulna alone most commonly occurs when the forearm is struck by an object (or by the forearm striking an object). It is commonly called a nightstick fracture. A break in the distal end of the humerus is an epicondylar fracture and is located at the elbow. A fracture of one or more of the carpal bones is not described by the term Colles fracture.