What is a key feature of synovial joints?

• A. They are freely movable and contain a synovial cavity with fluid
• B. They are immovable by design
• C. They have no joint capsule
• D. They do not require ligaments

Answer: (A)

Freely movable joints with a synovial cavity filled with fluid are a hallmark of synovial joints. This cavity houses synovial fluid, which lubricates the joint to minimise friction as the bones glide over each other. The joint is enclosed by a capsule and supported by ligaments, which together provide stability while preserving a wide range of motion. These features—high mobility, a lubricated cavity, and the enclosing capsule—distinguish synovial joints from other joint types. The other statements don’t fit because immovable joints lack this lubrication and movement capacity, and the presence of a capsule and ligaments is essential for synovial joints’ function.