Tendons are cord-like structures located where a muscle narrows down to attach to a bone. The tendon is more fibrous and dense than the elastic, fleshy muscle. A tendon transmits the pull of the muscle to the bone to cause movement. Tendinitis is often very tender to the touch.
Tendinitis or bursitis often involves the shoulder, elbow, wrist, hip, knee and ankle. The pain it causes may be quite severe and often occurs suddenly. As in arthritis, the pain is worse during movement. Unlike arthritis, the pain is often in parts of the body far from a joint. Tendinitis often results from repetitive use (overuse). Though the problem can recur or be chronic (long term) in some people, it is most often short term, mainly if treated early.
Bursitis is inflammation of a bursa. This small sac acts as a cushion between moving structures (bones, muscles, tendons or skin). If a muscle or tendon is pulling around a corner of a bone, or over a bone, a healthy bursa protects it from fraying and stress. When a bursa is inflamed, it becomes very painful, even during rest.