How does the elbow joint work?
The elbow joint is made up of three bones the humerus bone of the upper arm, and the ulna and radius bones of the forearm. The ulna and the humerus meet at the elbow and form a hinge. This hinge allows the arm to straighten and bend. The large triceps muscle in the back of the arm attaches to the point of the ulna (the olecranon). When this muscle contracts, it straightens out the elbow. The biceps muscles in the front of the arm contracts to bend the elbow. Inside the elbow joint, the bones are covered with articular cartilage. Articular cartilage is a slick, smooth material. It protects the bone ends from friction when they rub together as the elbow moves. Articular cartilage is soft enough to act as a shock absorber. It is also tough enough to last a lifetime, if it is not injured. The connection of the radius to the humerus allows rotation of the forearm. The upper end of the radius is round. This round end turns against the ulna and the humerus as the forearm and hand turn from pa
