The elbow is an example of a ______ joint.

The elbow is an example of a ______ joint.

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

Answer: (D)

Joints are classified by the type of movement they allow. An elbow primarily performs bending and straightening in one plane, which is exactly what a hinge joint does. The elbow’s main motion is flexion and extension at the humeroulnar and humeroradial joints, giving a uniaxial, back-and-forth arc like a door hinge. There is some forearm rotation (pronation and supination) that involves the proximal radioulnar joint, but that rotation is a separate pivot setup and does not define the elbow’s primary joint type. Ball-and-socket joints permit multi-directional movement (like the shoulder), saddle joints allow more varied motion at the thumb, and pivot joints enable rotation around a single axis in a different location. Because of its primary bending and straightening action in one plane, the elbow is a hinge joint.

Joints are classified by the type of movement they allow. An elbow primarily performs bending and straightening in one plane, which is exactly what a hinge joint does. The elbow’s main motion is flexion and extension at the humeroulnar and humeroradial joints, giving a uniaxial, back-and-forth arc like a door hinge. There is some forearm rotation (pronation and supination) that involves the proximal radioulnar joint, but that rotation is a separate pivot setup and does not define the elbow’s primary joint type. Ball-and-socket joints permit multi-directional movement (like the shoulder), saddle joints allow more varied motion at the thumb, and pivot joints enable rotation around a single axis in a different location. Because of its primary bending and straightening action in one plane, the elbow is a hinge joint.