Dorsal wrist ganglion

Illustration copyright 2004 by Nucleus Communications, Inc. All rights reserved. http://www.nucleusinc.com

Ganglions are small sacs (cysts) filled with clear, jellylike fluid. They often appear as bumps on the hands and wrists, but they can also develop on feet, ankles, knees, or shoulders. A ganglion can grow out of a joint capsule, which surrounds and protects the joint, or a tendon sheath, which covers the tendon (the ropelike fibers connecting muscle to bone). Most people with ganglions notice that the bumps appear suddenly.