what forms a wrapper around tendons
In areas in which there is a marked change in direction of a tendon or in which a tendon passes under a ligamentous band or through a fascial sling, a tendon sheath or synovial sheath surrounds it. The tendon invaginates into the sheath to form a closed double-walled cylinder. The inner layer, the visceral layer, is closely attached to the tendon by areolar tissue. The outer layer, the parietal layer, is attached to adjacent connective tissue or periosteum. Because of this method of formation, the inner and outer layers are usually connected by an elongated mesentery, the mesotendon.