Final answer:
The elbow is a joint formed by the humeroulnar joint and humeroradial joint, allowing only for flexion and extension of the forearm. It is supported by collateral ligaments and the annular ligament, with all three joints enclosed in a single capsule.
Step-by-step explanation:
The elbow is an example of a joint. This type of joint allows for back and forth movement, similar to the on a door, enabling the arm to bend and extend. The joint is uniaxial, meaning it permits movement in one plane or axis, predominantly allowing for flexion and extension of the forearm.
The elbow joint is formed by the articulation between the humerus (the upper arm bone) and the bones of the forearm (the radius and ulna). The precise joints involved are the humeroulnar joint between the humerus and the ulna, and the humeroradial joint between the humerus and the radius. Further associated with the elbow region is the proximal radioulnar joint, which is a pivot joint that allows for rotation of the radius.
Supporting structures of the elbow joint include the ulnar and radial collateral ligaments, which provide lateral stability, and the annular ligament, which supports the head of the radius within the proximal radioulnar joint. All three joints associated with the elbow are enclosed within a single articular capsule.