Summary

Summary

Joints can be classified according to their degree of movement and by the type of tissue that binds together the bones that surround them. Joints are divided into fibrous, cartilaginous, and synovial types. Fibrous joints are tightly joined by a layer of dense connective tissue. They include sutures, syndesmoses, and gomphoses. Fibrous joints may be amphiarthrotic (having little movement, such as cartilaginous joints) or synarthrotic (immov-able). Cartilaginous joints include synchondroses and symphyses. Synovial joints are covered with hyaline cartilage and are held together by a fibrous joint capsule. Synovial joints that allow free move ment (diarthrotic)­ include ball -and-socket, hinge, ­condyloid, gliding, saddle, and pivot types. Syno-vial joints include characteristics such as articular cartilage,­ articular cavities, articular capsules, ­synovial fluid, reinforcing ligaments, nerves, and blood vessels. Examples of synovial joints include the ­shoulder, elbow, hip, knee, and TMJs. Both bursae­ and tendon sheaths are closely related to synovial joints.

Joint movements include flexion, extension, dorsiflexion, plantar flexion, hyperextension, supination, eversion, inversion, rotation, circumduction, pronation, supination, abduction, adduction, retraction, protraction, depression, and elevation. Joints must be stabilized to avoid becoming dislocated during stretching and compression. Muscle tendons crossing joints are often the most important factors concerning stability. As we age, joints may develop conditions such as arthritis or rheumatism. Many people over age 60 have osteoarthritis, which is also known as degenerative joint disease. Rheumatoid arthritis is an autoimmune­ disease­ that affects the joints. Gouty arthritis involves uric acid crystals ­forming in the synovial joint fluid.