Tendonitis is inflammation or irritation of a tendon.
Tendons are the thick fibrous cords that attach muscles to bone.
They function to transmit the power generated by a muscle contraction to move a bone. Bursitis is inflammation or irritation of a bursa. Bursa are small sacs located between bone and other moving structures such as muscles, skin or tendons. The bursa allows smooth gliding between these structures. Since both tendons and bursa are located near joints, inflammation in these soft tissues will often be perceived by patients as joint pain and mistaken for arthritis.