This type of joint is similar to the opening and closing of a door.

• A. Gliding joint
• B. Movable joint
• C. Ball and socket joint
• D. Hinge joint

Answer: (D)

Opening and closing a door is driven by a hinge that allows movement mainly in one plane around a single axis. In the body, a hinge joint works the same way: the ends of the bones meet in a way that favors bending and straightening, like the elbow or knee. This creates angular movement in one direction with limited rotation, which is why the door analogy fits so well. Other joints move differently: gliding joints slide past each other rather than bending in one plane; a ball-and-socket joint allows movement in many directions and rotation; and a “movable joint” is a generic term that doesn’t describe a specific type of joint.