What tendon is inflamed in De Quervain's tenosynovitis?

• A. Flexor pollicis longus
• B. Extensor pollicis brevis
• C. Abductor pollicis longus
• D. Extensor pollicis longus

Answer: (B)

In De Quervain's tenosynovitis, the inflammation primarily affects the tendons that control thumb movement, specifically the extensor pollicis brevis and the abductor pollicis longus. These tendons pass through the first extensor compartment of the wrist.

In this condition, overuse or repetitive motions can lead to irritation and swelling of the synovial sheath that surrounds these tendons, causing pain and difficulty with thumb motion and gripping. This irritation is often exacerbated by activities involving lifting or pinching, which engage these particular tendons.

While the other tendons mentioned can be involved in different conditions or scenarios, they are not the main focus of inflammation in De Quervain's tenosynovitis. The flexor pollicis longus, for example, is responsible for flexing the thumb and is located in a different compartment, thus not contributing to this condition. Understanding the anatomy and function of these specific tendons can help clarify why extensor pollicis brevis and abductor pollicis longus are central to the diagnosis and treatment of De Quervain's tenosynovitis.