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

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.