Final answer:
Arthrocentesis is the procedure used to aspirate fluid from the synovial cavity of a joint, typically to reduce swelling or to diagnose a condition.
Step-by-step explanation:
The surgical puncture of a joint to withdraw or aspirate fluid from the synovial cavity is a medical procedure commonly known as arthrocentesis. In a synovial joint, which is a type of diarthrosis joint, there is a fluid-filled space known as the synovial cavity that separates the articulating bones. This cavity is bordered by the articular capsule and contains synovial fluid, which serves as a lubricant to reduce friction and allow for smooth movement of the joint. Examples of synovial joints include the knee, elbow, and shoulder, all capable of significant range of motion. When excess fluid accumulates in this cavity, it may need to be removed for diagnostic or therapeutic reasons through arthrocentesis.