Introduction:
Synovial fluid is a clear, viscous fluid that is found in freely movable joints in the human body. It plays a crucial role in lubricating and nourishing these joints. Let's delve deeper into the details and understand why synovial fluid is found in freely movable joints.

Explanation:
1. Definition of synovial fluid:
Synovial fluid is a thick, gel-like substance that is produced by the synovial membrane, which lines the inner surface of the joint capsule. It acts as a lubricant, reducing friction between the bones and allowing smooth movement of the joints.

2. Characteristics of freely movable joints:
Freely movable joints, also known as synovial joints, are characterized by their ability to move in various directions. These joints are found in the limbs and include the ball-and-socket joints (e.g., hip and shoulder joints), hinge joints (e.g., elbow and knee joints), and pivot joints (e.g., neck joint).

3. Structure of freely movable joints:
Freely movable joints consist of several components, including:
- Articular cartilage: Covers the ends of the bones and provides a smooth surface for movement.
- Joint capsule: Surrounds the joint and helps maintain its stability.
- Synovial membrane: Lines the inner surface of the joint capsule and secretes synovial fluid.
- Synovial fluid: Fills the joint cavity and provides lubrication, nourishment, and shock absorption.

4. Functions of synovial fluid in freely movable joints:
Synovial fluid performs several essential functions in freely movable joints, including:
- Lubrication: It reduces friction between the bones, allowing smooth movement and preventing wear and tear.
- Nutrient supply: Synovial fluid delivers nutrients and oxygen to the articular cartilage, which lacks a direct blood supply.
- Shock absorption: It helps absorb shock and distributes the forces evenly across the joint, protecting the bones and other structures.
- Waste removal: Synovial fluid carries away metabolic waste products from the joint.

Conclusion:
Synovial fluid is found in freely movable joints because these joints require lubrication, nourishment, shock absorption, and smooth movement. The synovial fluid, produced by the synovial membrane, plays a vital role in maintaining the health and functionality of these joints.