The elbow joint is a typical compound joint, being formed by the association of the lower end of the humerus with the upper ends of the radius and ulna, and so consisting of three articulations. The three articulations share a common articular capsule, which is roomy and relaxed, particularly in front and behind. The humero-ulnar portion of the elbow joint involves the trochlea of the humerus and the trochlear notch of the ulna. The flexion of the forearm upon the arm is not a pure hinge motion, but rather that of a spiral joint, since the surfaces of the trochlea and the median ridge of the trochlear notch resemble that of the ridge of a screw. From a practical standpoint, however, the elbow may be regarded as a hinge joint, whose axis of movement passes through the two epicondyles.

Articulatio humeroulnaris

Articulation huméroulnaire