Final answer:
A ganglion cyst is a fluid-containing swelling attached to the synovial sheath of a tendon. It differs from a bursa, which serves to reduce friction in different bodily locations, and from tendonitis or tenosynovitis, both of which are inflammatory conditions.
Step-by-step explanation:
The fluid-containing swelling attached to the synovial sheath of a tendon is referred to as a ganglion cyst. A tendon sheath is a layer of connective tissue that encases a tendon at locations where the tendon crosses a joint. This sheath contains a lubricating fluid to prevent friction and enable smooth movements of the tendon during muscle contraction and joint activities.
The other options provided—bursa, tendonitis, and tenosynovitis—have different characteristics than the condition described. A bursa is a small fluid-filled sac that helps reduce friction between tissue, such as skin, muscle, or tendon, and an underlying bone. Tendonitis is the inflammation of the tendon itself, and tenosynovitis is an inflammation of the sheath around a tendon.