Which of the following describes the main function of a pivot joint?

A pivot joint primarily allows for movement around a single axis, enabling rotational movement. This type of joint is exemplified by the articulation between the first and second cervical vertebrae in the neck (the atlas and axis), which permits the head to turn from side to side. This flexibility and rotation are key characteristics of pivot joints, making them significant for certain movements in the body, such as shaking the head to indicate “no.”

Other choices highlight features that are not specific to pivot joints. For instance, limited stability is not a defining characteristic of pivot joints, as stability can vary depending on the specific joints and surrounding structures. While some joints do allow for a wide range of motion (like ball-and-socket joints), pivot joints are more restricted in their movement, focusing specifically on rotation. Support of weight is more aligned with joints that bear weight, such as the hip or knee joints, rather than the rotational focus of pivot joints. Thus, the main function of a pivot joint is accurately captured by its ability to facilitate flexibility and rotation.