The elbow is the region surrounding the elbow-joint-the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm. The bony prominence at the very tip of the elbow is the olecranon process of the ulna, and the inner aspect of the elbow is called the antecubital fossa. [WP,unvetted,human-specific]. [ http://en.wikipedia.org/wiki/Elbow ]