A hinge joint is a type of synovial joint that allows movement in one plane, similar to the way a door swings open and closed. This joint structure enables flexion and extension, making it essential for various body movements. Common examples of hinge joints include the elbow and knee. Hinge joints are characterized by a cylindrical end of one bone fitting into a trough-shaped surface of another bone. This design provides stability while allowing for a limited range of motion. The presence of ligaments and cartilage around these joints helps to support and cushion them during movement.