Which of the following describes the joint between the humerus and ulna?

Which of the following describes the joint between the humerus and ulna?

• A. A gliding joint allowing supination and pronation
• B. A hinge joint allowing flexion and extension
• C. A condyloid joint allowing abduction and adduction
• D. A pivot joint allowing internal and external rotation

Answer: (B)

The joint between the humerus and ulna is classified as a hinge joint, which primarily allows for flexion and extension movements. This structure enables the arm to bend at the elbow, allowing tasks such as lifting and lowering the forearm. Hinge joints are characterized by their motion in one direction, akin to the movement of a door, which is exactly how the elbow operates when flexing and extending. To further clarify, while other types of joints like gliding, condyloid, and pivot joints serve specific functions—such as rotational movements or movement in multiple planes—the humeral-ulnar joint's primary role is simple bending and straightening. This function is foundational for many daily activities and movements that involve the upper extremities.

The joint between the humerus and ulna is classified as a hinge joint, which primarily allows for flexion and extension movements. This structure enables the arm to bend at the elbow, allowing tasks such as lifting and lowering the forearm. Hinge joints are characterized by their motion in one direction, akin to the movement of a door, which is exactly how the elbow operates when flexing and extending.

To further clarify, while other types of joints like gliding, condyloid, and pivot joints serve specific functions—such as rotational movements or movement in multiple planes—the humeral-ulnar joint's primary role is simple bending and straightening. This function is foundational for many daily activities and movements that involve the upper extremities.