Humeroulnar Joint (Elbow Hinge) - is the main source of movement for extension and flexion of the arm.

Bones: Humerus and ulnar.

Cartilage: There is a capsule sealing the two bones together.

Ligaments: Ulnar collateral ligament, which holds the bones together.

Tendon: Of the triceps brachii attaching by the olecranon process (bony tip of the elbow).

Muscles: The triceps brachii contracts, extending the joint moving the arm away from the body. The hing is able to bend in the opposite direction but there is no muscle attached to both of these bones that is responsible.

Joint type: Hinge.

Mechanics: The triceps are often under rated by people wanting big (showy) biceps. For example using the triceps is the main force of extending the arms and pushing the body in an elbows in push up. Many strikes like chops involve the forearm shooting out with high speed and power all caused by the the triceps.

Range of motion: The mechanical force of this joint only moves in one direction so that the ulnar is is straight and inline with the humerus.

Injury: Falling on the olecranon process can break the bone, rip the tendon and ligaments thus proper falls should be practiced.

Minipulation: This joint goes no further than 180 degrees in line with the humerus, therefor pressure or a strike to the back of the elbow after it being fully extended can cause immense damage to every portion of the joint.

This joint makes "half" of the elbow joint, the other being the Humeroradial Joint (Stabilizer) which moves the forearm in the opposite direction.

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