Certified Instrument Specialist (CIS) Practice Exam 2025 - Free CIS Practice Questions and Study Guide

The term "articular surface" refers specifically to the areas on the ends of bones that come into contact with each other at a joint. These surfaces are typically covered with articular cartilage, which helps reduce friction and absorb shock during movement. The design of the articular surfaces plays a crucial role in the overall function and stability of joints.

In contrast, the cortical layer refers to the dense outer surface of bones, primarily involved in providing strength and support, rather than defining joint interaction. The synovial membrane is an important structure within certain joints, as it secretes synovial fluid for lubrication, but it is not the area where bones articulate. The periosteum, which is a layer of connective tissue surrounding bones, also serves different functions such as nourishment and attachment points for tendons and ligaments, rather than being directly involved in a joint's interface.

Therefore, "articular surface" accurately defines the specific area involved in the anatomy and function of joints, making it the appropriate choice for the question asked.