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Chapter 8 Joints J.F. Thompson, Ph.D. & J.R. Schiller, Ph.D. & G. Pitts, Ph.D. Classification of Joints Table 8.1 - Summary of Joint Classes Structural Fibrous - bones joined by fibrous connective tissue; no joint cavity Cartilaginous - bones joined by cartilage; no joint cavity Synovial - bones separated by fluid filled cavity Functional Synarthroses - non-movable Amphiarthroses - slightly movable Diarthroses - freely movable Fibrous Joints Suture - wavy border with dense fibrous connective tissue which penetrates into both bone Syndesmosis connected by a ligament Gomphosis - peg in a socket (teeth) Cartilaginous Joints Synchondroses hyaline cartilage epiphyseal plate • most limb bones most ribs to sternum Symphyses fibrocartilage pelvis, vertebrae Synovial Joints General Structure articular cartilage synovial (joint) cavity articular capsule synovial fluid reinforcing ligaments meniscus – a fibrocartilage pad, e.g., at the tempero-mandibular joint (TMJ) and at the tibio-femoral (knee) joint Synovial Joints Bursae - flattened sacs filled with synovial fluid Tendon sheath - elongated bursa which wraps around a tendon Synovial Joints Gliding (plane) joint flat planes gliding over each other intercarpal and intertarsal joints Synovial Joints Hinge cylindrical projection fits into a notch ulna and humerus tibia and femur interphalangeal joints Synovial Joints Pivot rounded end of one bone protrudes into sleeve or ring of bone or ligaments atlas (C1) and dens of the axis (C2) proximal radio-ulnar joint Synovial Joints Condyloid rounded (convex) articulating surface of one bone fits into concave depression on the other bone radio-carpal joints metacarpal-phalangeal joints Synovial Joints Saddle each articular surface has both convex and concave areas carpo-metacarpal joint of the thumb special case of a condyloid joint Synovial Joints Ball and Socket spherical or hemispherical head of one bone articulates with cuplike socket provides greatest rotational flexibility shoulder hip special case of a condyloid joint which is capable of circumduction Know the Terminology for Types of Motions in Your Lab Guide Gliding Rotation Flexion/Extension Abduction/Adduction Circumduction Special Movements Reviewed in lab Factors Influencing Joint Stability Articular surfaces – shape and condition are important for smooth functioning of the joint Ligaments – dense regular fibrous connective tissue which will only stretch ~6% before tearing Muscle Tone most important tone - resting activity – some minimal level of contraction operating at all times muscles, tendons, and ligaments are supplied with sensory nerve endings for feedback control of limb and body position and posture Sagittal View of Knee Joint The knee joint is a classic site for repeated injuries. Since cartilage does not repair well, the cumulative effect of multiple traumas is to permanently weaken the joint. Anterior view. Knee joint relationships with some associated muscles • Ligaments and tendons contribute to joint stability. • Physical therapists and practitioners of sports medicine must become expert in the anatomy of the musculoskeletal system. A common knee injury A blow from the side forces the bones to move in a direction incompatible with the joint’s design. Ligaments are not flexible so they tear. They can repair with time. Cartilage repair will be minimal. Anterior Cruciate Ligament (ACL) Injury ACL torn above → & repaired below; screws stabilize the repair. Arthritis More than 100 different types of inflammatory or degenerative joint diseases Most common crippling diseases in the U.S. Symptoms – pain, stiffness, and swelling of joint(s) Acute forms are caused by bacteria and are treated with antibiotics Chronic forms include osteoarthritis (OA), rheumatoid arthritis, and gouty arthritis After the End of Chapter 8, You Will Find Some Additional Slides with More Detailed Information on Certain Topics for Your Review End Chapter 8 Gliding Movement Figure 8.5a Angular Movement Rotational Movement Special Movements Ligaments and Tendons of Knee all contribute to stability many contribute to fibrous capsule Sprains The ligaments reinforcing a joint are stretched or torn Partially torn ligaments slowly repair themselves Completely torn ligaments require prompt surgical repair Cartilage Injuries The snap and pop of overstressed cartilage Common aerobics injury Repaired with arthroscopic surgery Dislocations Occur when bones are forced out of alignment Usually accompanied by sprains, inflammation, and joint immobilization Caused by serious falls and are common sports injuries Subluxation – partial dislocation of a joint Inflammatory and Degenerative Conditions Bursitis An inflammation of a bursa, usually caused by a blow or friction Symptoms are pain and swelling Treated with anti-inflammatory drugs; excessive fluid may be aspirated Tendonitis Inflammation of tendon sheaths typically caused by overuse Symptoms and treatment are similar to bursitis Developmental Aspects of Joints By embryonic week 8, synovial joints resemble adult joints Few problems occur until late middle age Advancing years take their toll on joints: Ligaments and tendons shorten and weaken Intervertebral discs become more likely to herniate Most people in their 70s have some degree of OA Prudent exercise (especially swimming) that coaxes joints through their full range of motion is key to postponing joint problems End Chapter 8 End of extra review slides