Final answer:
A synovial joint allows for significant movement between two bones due to a synovial cavity filled with lubricating fluid, with the ball-and-socket joint like the shoulder joint providing the widest range of motion.
Step-by-step explanation:
The type of structural joint that exhibits a significant amount of movement due to the presence of a small synovial cavity between two bones is called a synovial joint. These joints are characterized by a synovial (or joint) cavity filled with synovial fluid, which serves to lubricate the joint, thus reducing friction and facilitating a greater range of motion. The bones in synovial joints are capped with articular cartilage, and the entire joint structure is encompassed by an articular capsule made up of connective tissue. Synovial joints have the capability for extensive movement, and examples include the knees, elbows, and shoulders. Among various synovial joints, the ball-and-socket joint such as the shoulder joint, allows for the widest range of motion.