The elbow joint is a synovial hinge joint formed between the trochlea of the humerus above and the trochlear notch of the ulna and head of the radius below. It allows for flexion and extension and is stabilized by the medial and lateral collateral ligaments and surrounding muscles like the brachialis. Common injuries include dislocations, especially posteriorly, and epicondylitis due to overuse of muscles like the extensors controlling forearm pronation and supination.