Tendons are tough bands of connective tissue made up mostly of a rigid protein called collagen. Tendons firmly attach each end of a muscle to a bone Bones Bone, although strong, is a constantly changing tissue that has several functions. Bones serve as rigid structures to the body and as shields to protect delicate internal organs. They provide... read more . They are often located within sheaths, which are lubricated to allow the tendons to move without friction.
Bursae are small fluid-filled sacs that can lie under a tendon, cushioning the tendon and protecting it from injury. Bursae also provide extra cushioning to adjacent structures that otherwise might rub against each other, causing wear and tear—for example, between a bone and a ligament Ligaments Ligaments are tough fibrous cords composed of connective tissue that contains both collagen and elastic fibers. The elastic fibers allow the ligaments to stretch to some extent. Ligaments surround... read more or a bony prominence and overlying skin (such as in the elbow, kneecap, or shoulder area).