define tenosynovitis
Tenosynovitis is inflammation of the lining of the sheath that surrounds a tendon (the cord that joins muscle to bone). The synovium is a lining of the protective sheath that covers tendons. Tenosynovitis is inflammation of this sheath. The cause of the inflammation may be unknown, or it may result from: Diseases that cause inflammation.
Tenosynovitis, De Quervain's: De Quervain's tenosynovitis is inflammation of tendons on the side of the wrist at the base of the thumb. These tendons include the extensor pollicis brevis and the abductor pollicis longus tendons. De Quervain's tenosynovitis typically is associated with pain when the thumb is folded across the palm and the fingers are flexed over the thumb as the hand is pulled away from the involved wrist area.