All joints are encased by a tough capsule. Capsules are reinforced by strap-like bands called ligaments. Capsules and ligaments have little 'give' and are common sites for injury. Muscles and Tendons Muscles are fleshy tissues, richly supplied with blood vessels. They contract and shorten, or relax and lengthen.
Tendons are strong cable-like structures, which anchor the muscles to the bone.
The muscle-tendon unit is responsible for producing movement at the joints. When compared to muscles, tendons have a poor blood supply and therefore heal at a slower rate.