![]() ![]() Gomphoses are fibrous joints with a peg-in-socket structure. When they are longer, more movement is possible, for example, the interosseous membrane (similar to a ligament) that connects the ulna and radius. Syndesmoses with shorter fibers have little or no allowed “give” (movement), for example, the ligament connecting the distal ends of the fibula and tibia. The varied lengths of these fibers control the amount of movement that can occur. ![]() In syndesmoses, ligaments connect the bones and the connecting fibers are longer than those found in sutures. The immo-bility of the sutures helps to protect the brain. Closed sutures, during brain growth, are better described as synostoses. However, they also allow the skull to expand during childhood, when the brain is growing. These fibers are continuous with the periosteum, creat-ing rigid structures joining the bones together. Each junction is totally filled by a tiny amount of extremely short connective tissue fibers. They have waved and articulated bone edges that interlock. Sutures are seams that occur only between the bones of the skull. There are three types of fibrous joints: sutures, syndesmoses, and gomphoses. The amount of movement they have depends on the length of the connective tissue fibers that unite the bones. Those with limited movement (amphiarthrotic) include the joint between the distal tibia and fibula. No real movement takes place in most fibrous joints, making them synar-throtic in classification. An example of a fibrous joint is a suture between flat bones of the skull. Lying between bones that are in close contact with each other, fibrous joints are joined by a thin, dense connective tissue ( FIGURE 8-1 ). Compare amphiarthrotic with synarthrotic joints. List the three types of joints as classified by their degrees of movement.Ģ. TABLE 8-1 shows functional classifications of joints.ġ. Cartilaginous joints may be either rigid or slightly movable. In general, fibrous joints are immovable, whereas synovial joints are freely movable. They can also be structurally grouped according to the type of tissue binding them at their junctions such as fibrous, carti-laginous, and synovial joints. Less movable joints usually have more stability. Joints are functionally classified as immovable ( synarthrotic ), slightly movable ( amphiarthrotic ), or freely movable ( diarthrotic ). ![]()
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