Joints Chapter 8

Classifying Joints Functions Classification Flexibility for movement Hold bones together Structural Functional Fibrous Joints Cartilaginous Joints Synovial Joints Binding material Joined by fibrous tissue Joined by articular (hyaline) cartilage Separated by synovial fluid cavity Cavity Present No Yes Functional Type Synarthroses (immovable) Amphiarthroses (slightly movable) Diarthroses (freely movable) Examples Sutures Syndesmoses Gomphoses Synchondroses Symphyses Joints of limbs

Fibrous Joints Sutures Syndemoses Gomphoses 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.g interosseous membrane and tibia-fibula distal ends Gomphoses Tooth in alveolar socket E.g periodontal ligament

Cartilaginous Joints Synchondroses Symphyses 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

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

Synovial Joints Prevent friction Provide stability 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

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)

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

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

Temporomandibular Joint (TMJ) Mandibular condyle 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

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;