Huumeroradial Joint - the other "half" of the elbow.

Bones: The humerus and the radius.

Cartilage: There is a simple capsule that connects the two bones.

Ligaments: The anterior ligaments binds the two. The annular ligament stabilizes the joint binding the head of the radius to the ulnar right under the anterior ligaments binding the humerus to the radius.

Tendon: Tendon of the biceps brachii.

Muscles: The biceps brachii contracts pulling on the head of the radius and moving it and subsequently the ulnar along with it.

Joint type: This is a ball and socket joint which acts like a hinge.

Mechanics: The contraction of the biceps allows for flexion of the whole forearm towards the body, therefor this joint technically only moves one way. The stabilizing annular ligament prevents the two relatively shallow joints of the elbow from being dislocated especially that of the humerus and radius, otherwise the bicep itself is strong enough to dislocate the joint.

Range of motion: This joint is able to flex the forearm towards the body from straight roughly 150 degrees before the forearm hits the bicep.

Injury: The main thing to worry about here is over lifting, as the muscle can be made stronger than the tendon and ligaments. Impact to the side of the arm resulting in moderate arm pain could in fact be a partly dislocation of this joint.

Manipulation: Extreme pressure to the back of the elbow can dislocate the humeroulnar and the humeroradial joint. Striking the inside of the elbow will hit the tendon of the biceps brachii causing partial involuntary flexion of the arm, very useful for when the attacker is trying to keep their arm straight grabbing or choking you. Continued force to the back of the wrist while the arm is flexed will put a large amount of stress on the triceps tendon connected to the ulna.

This joint forms flexing portion of the elbow joint, for the other "half" of the joint please read the Humeroulnar Joint (Elbow Hinge) page.

For information on additional joints please refer back to the Joints page.