What type of joint is characterized by being synovial and moving in one plane, such as the elbow?

• A. Hinge joint
• B. Pivot joint
• C. Saddle joint
• D. Ball-and-socket

Answer: (A)

A hinge joint moves in one plane, making it uniaxial. This type of synovial joint primarily allows flexion and extension, which is exactly what happens at the elbow. The elbow’s structure supports bending and straightening in the sagittal plane, with the joint capsule and ligaments stabilizing the motion while the articular surfaces guide the hinge action.

Other joint types involve rotation or movements in multiple planes. A pivot joint mainly rotates around a vertical axis (think turning the head side to side). Ball-and-socket joints permit movement in all directions and rotation. Saddle and condyloid joints allow movement in two planes, not just one.