Which type of synovial joint allows movement in multiple planes and includes the ball-and-socket joint?

• A. Hinge joint
• B. Pivot joint
• C. Ball-and-socket (multiaxial) synovial joint
• D. Saddle joint

Answer: (C)

Movement in multiple planes is a hallmark of multiaxial synovial joints. These joints permit motion around several axes, including flexion-extension, abduction-adduction, and rotation. The ball-and-socket joint is the classic example: the rounded head of one bone fits into a cup-like socket of another, allowing the limb to move in nearly all directions, as seen in the shoulder and hip.

In contrast, hinge joints restrict movement to a single plane (like bending and straightening the elbow), pivot joints enable rotation around one axis (such as turning the head on the neck), and saddle joints are biaxial, allowing movement in two planes but not the full range of rotation.