The elbow joint is a compound joint, mainly composed of three joints, tendon ligaments, and neurovascularization. 1. Three joints: including the brachio-ulnar joint, the brachioradial joint, and the proximal radial-ulnar joint. (1) Humerus-ulnar joint: the main joint of the elbow joint, composed of the humeral slide and the ulnar slide tangent. (2) Humeral-radial joint: composed of the humeral tuberosity and the articular recess of the radius. (3) Proximal radial-ulnar joint: consists of the circumferential articular surface of the radius with the radial notch of the superior end of the bone. The three joints are collectively encased in a joint capsule. 2. Tendon ligaments: the anterior and posterior walls of the joint capsule of the elbow joint are weak, so the joints rely on tendon ligaments to reinforce and stabilize each other. They mainly include the medial and lateral collateral ligaments, triceps and biceps tendons, pronator teres and pronator teres. 3. Neurovascular: mainly including ulnar nerve, radial nerve, median nerve, brachial artery, median elbow vein and so on. The main role of the nerve is to innervate the sensation and movement of the forearm, wrist joint and hand. The role of blood vessels is to nourish muscles and tendons as well as nerves.