Joints

1. Joints Chapter 8

2. Classifying Joints Functions Classification Structural Functional • Flexibility for movement • Hold bones together

3. Fibrous Joints • Sutures • Only b/w skull bones • Bind, but allow growth • As an adult CT ossifies = synostoses • Syndemoses • Longer than sutures • Length of ligament determines mov’t • E.ginterosseous membrane and tibia-fibula distal ends • Gomphoses • Tooth in alveolar socket • E.g periodontal ligament

4. Cartilaginous Joints • Synchondroses • Temporary, become synostoses • E.g Epiphyseal plates and coastal cartilage • Symphyses • Cartilage fused to fibrocartilage pad/plate • Strength with flexibility • E.g. intervetevbral discs and pubic symphysis

5. Synovial Joint Structure • Synovial cavity filled w/ synovial fluid • Viscous, but thins with mov’t • Articular capsule enloses cavity • Fibrous capsule (ext-) DICT • Synovial membrane (int-) LCT • Articular cartilage (hyaline) • Reinforcing ligaments • Double jointed = looser/stretchier ligaments and capsule

6. Synovial Joints • Prevent friction • Bursae are flattend fibrous synovial sacs • Tendon sheaths are elongated bursa wrapped around a tendon • Provide stability • Articular surface shape • Determine mov’t & some stability • Ligaments • Prevent excessive/undesirable mov’t • Inadequate stabilization stretches (taffy) = snapping • Muscle tone • Tendons stay taut so reactive

7. Synovial Joint Shapes • Plane - intercarpal and –tarsals • Slip 1 or 2 ways (A) • Hinge – elbow and interphalengeal • 1 plane of mov’t (B) • Pivot – C1 & C2 or radius & ulna (C) • 1 plane of mov’t • Condyloid - metacarpophalangeal (knucles) • 2 planes of mov’t (D) • Saddle – carpometacarpal joint (thumb) • 2 planes of mov’t (E) • Ball and socket – shoulder or hip joint • 3 planes mov’t (F)

8. Synovial Joint Movements • Gliding • Slips surfaces across one another • Flexion/extension • Reduces angle of joint/ increases angle • Abduction/adduction • Away from center/ toward midline • Pronation/supination • Face or palm down/ face or palm up • Rotation/circumduction • Turning on an axis/ making small circles • Inversion/eversion • Turn sole medially/ turn sole laterally • Dorsiflexion/plantar flexion (foot and wrist) • Flex/ point • Protraction/retraction • Jaw out/jaw in • Elevation/depression • Lift superiorly/move inferiorly

9. Knee Joint • Single cavity w/ 3 joints • Capsule partially encloses • Strong vertical force, weak lateral • Patellar ligament (knee-jerk) • Prevent hyperextension • Fibular and tibial collateral ligaments • Prevent lateral and medial rotation w/extension • Anterior and posterior cruciate ligaments (tibial attachment) • ACL: runs up posteriorly & laterally; prevents forward tibia mov’t • PCL: runs up anteriorly & medially; prevents backward tibia & forward femur mov’t • Lateral and medial meniscus anterior cruciate ligament

10. Temporomandibular Joint (TMJ) • Mandibularcondyle and fossa mismatched shape • Shallow socket = easy dislocation • Reset: thumbs in molars, push inferior and posterior • Pain and disorders from muscles tension • Lateral exclusion, side to side mov’t, unique to mammals • Grinding, clenching, biting

11. Clinical Terms • Sprain: stretching/tearing of a ligament • Dislocation (luxation): bones forced out of position • Bursitis: inflammation on bursa; blow or friction • Arthritis: synovial membrane thickens, production decrease • Osteoarthritis – degenerative; tissue thickens & bone spurs formed • Rheumatoid arthritis - autoimmune • Gouty arthritis – uric acid accumulation in soft tissue joints • Synovitis: inflammation of synovial membrane • Tendinitis: inflammation of tendon sheaths, overuse;