What best describes a tendon sheath?

• A. A capsule surrounding a synovial joint
• B. A thin layer of cartilage covering the bone ends
• C. An elongated bursa that wraps around a tendon
• D. A ligament connecting bones

Answer: (C)

A tendon sheath is a lubricated, tube-like sleeve formed by the synovial membrane that surrounds a tendon along its length, effectively an elongated bursa wrapping around the tendon to allow smooth, low-friction movement as the tendon glides. This wrapping reduces wear and friction where tendons pass through tight spaces, like in the fingers or wrist. It’s not a joint capsule, which surrounds an entire joint; nor articular cartilage, which covers the ends of bones; nor a ligament, which connects bones.