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Joints

9. Joints. I. Joints. ► bones meet at joints ( articulations ) ► a rthro = joint ► Joints can be classified by function or structure. A. Functional classification is based on amount of movement 1. Synarthroses —immovable 2. Amphiarthroses —slightly movable

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Joints

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  1. 9 Joints

  2. I. Joints ► bones meet at joints (articulations) ► arthro = joint ► Joints can be classified by function or structure

  3. A. Functional classification isbased on amount of movement 1. Synarthroses—immovable 2. Amphiarthroses—slightly movable 3. Diarthroses—freely movable B. Structural classificationis based on: ► Material that binds bones together ► Presence or absence of a joint cavity 1. Fibrous 2. Cartilaginous 3. Synovial

  4. Summary of Joint Classes

  5. II. Fibrous Joints A. bones are connected by fibrous connective tissue B. do not have a joint cavity C. most are immovable or slightly movable ► Sutures ► Syndesmoses ► Gomphoses

  6. Sutures A. bones are tightly bound by a minimal amount of fibrous tissue B. occur only between the bones of the skull C. allow bone growth so the skull can expand ► Synostoses—closed sutures

  7. Syndesmoses A. bones are connected exclusively by ligaments e.g. tibio-fibular joint—immovable synarthrosis e.g. interosseous membrane between radius and ulna ► diarthroses

  8. Gomphoses e.g. tooth in a socket connecting ligament—the periodontal ligament

  9. III. Cartilaginous Joints A. bones are united by cartilage B. lack a joint cavity C. two types: ► Synchondroses ► Symphyses

  10. Synchondroses A. hyaline cartilage unites bones e.g. epiphyseal plates of long bones e.g. Joint between first rib and manubrium Synchondroses Bones united by hyaline cartilage Sternum (manubrium) Epiphysealplate (temporaryhyaline cartilagejoint) Joint betweenfirst rib andsternum (immovable)

  11. Symphyses A. fibrocartilage unites bones B. resists tension and compression C. slightly movable joints that provide strength with flexibility ► Intervertebral discs ► Pubic symphysis Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginousintervertebral disc(sandwiched betweenhyaline cartilage) Pubic symphysis

  12. IV. Synovial Joints A. most movable type of joint B. all are diarthroses C. each contains a fluid-filled joint cavity D. ends of opposing bones are covered with hyaline cartilage ► absorbs compression

  13. V. General Structure of Synovial Joints A. articular cartilage ► ends of opposing bones are covered with hyaline cartilage ► absorbs compression B. joint (articular) cavity ► Unique to synovial joints ► Cavity holds a small amount of synovial fluid

  14. C. Articular capsule—joint cavity is enclosed in a two-layered capsule ► Fibrous layer—dense irregular connective tissue, which strengthens joint ► Synovial membrane—loose connective tissue - lines joint capsule and covers internal joint surfaces functions to make synovial fluid D. Synovial fluid ► viscous fluid similar to raw egg white ► arises from capillaries in synovial membrane ► contains glycoprotein molecules secreted by fibroblasts E. Reinforcing ligaments ► extracapsular ligaments—outside the capsule ► intracapsular ligaments—internal to the capsule

  15. Ligament Joint cavity (with synovial fluid) Articular (hyaline)cartilage Fibrouslayer Articularcapsule Synovialmembrane A typical synovial joint

  16. Articularcapsule A typical synovial joint

  17. VI. How Synovial Joints Function A. Are subjected to compressive forces ► Fluid is squeezed out as opposing cartilages touch ► Cartilages ride on the slippery film B. Bursa - a flattened fibrous sac lined by a synovial membrane C. Tendon sheath - an elongated bursa that wraps around a tendon ► closed bags of lubricant ► reduce friction between body elements

  18. Subacromialbursa Joint cavitycontainingsynovial fluid Fibrous layerof articularcapsule Articularcartilage Tendonsheath Synovialmembrane Fibrouslayer

  19. VII. Synovial Joints - Movements A. Three basic types of movement 1. Gliding—one bone across the surface of another 2. Angular movement—movements change the angle between bones 3. Rotation—movement around a bone's long axis

  20. Gliding Joints Gliding occurs between: ► carpals ► articular processes of vertebrae ► tarsals

  21. Angular Movements A. increase or decrease angle between bones 1. flexion & extension 2. abduction & adduction 3. circumduction

  22. Extension Flexion

  23. Extension Flexion

  24. Extension Flexion Flexion Extension

  25. Abduction Circumduction Adduction

  26. Rotation A. involves turning movement of a bone around its long axis B. only movement allowed between atlas and axis vertebrae C. occurs at the hip and shoulder joints

  27. Rotation Lateralrotation Medialrotation

  28. Elevation—lifting a body part superiorly Depression—moving the elevated part inferiorly ElevationLifting a body partsuperiorly DepressionMoving a body partinferiorly

  29. Protraction—non-angular movement anteriorly Retraction—non-angular movement posteriorly RetractionMoving a body part in theposterior direction ProtractionMoving a body part in theanterior direction

  30. Supination—forearm rotates laterally Pronation—forearm rotates medially Pronation (P)Rotating the forearm so thepalm faces posteriorly Supination (S)Rotating the forearm so thepalm faces anteriorly

  31. Inversion—turns sole medially Eversion—turns sole laterally InversionTurning the sole of the footmedially EversionTurning the sole of the footlaterally

  32. Dorsiflexion—lifting the foot so it approaches the shin Plantar flexion—depressing the foot, elevating the heel DorsiflexionFoot so it approaches the shin Plantar flexionElevating the heel

  33. A. Plane joint ► intertarsal and intercarpal joints ► movements are non-axial VIII. Synovial Joints - Shape Nonaxial movement Plane joint Metacarpals Flat articularsurfaces Gliding Carpals

  34. B. Hinge joints ► Angular movement is allowed in one plane ► Elbow, ankle, and joints between phalanges

  35. C. Pivot joints ► Proximal radio-ulnar joint

  36. D. Condylar (or ellipsoid)joints ► Side to side—abduction–adduction ►Back and forth—flexion–extension

  37. E. Saddle joints ► 1st carpometacarpal joint ► Allows opposition of the thumb

  38. IX. Selected Synovial Joints A. Shoulder (glenohumeral) joint ► The most freely movable joint lacks stability ► Muscle tendons contribute to joint stability

  39. Glenoid labrum Coracoacromialligament Synovial cavitycontainingsynovial fluid Subacromialbursa Fibrous layer ofarticular capsule Articularcartilage Tendonsheath Synovial membrane Fibrous layer ofcapsule Tendon ofbiceps Frontal section through right shoulder joint

  40. B. Elbow joint ► Allows flexion and extension ► Articulation of the humerus with the trochlear notch of the ulna ► Tendons of biceps and triceps brachii provide stability

  41. Humerus Anularligament Medialepicondyle Radius Articularcapsule Coronoidprocessof ulna Ulnarcollateralligament Ulna Cadaver photo of medial view of right elbow

  42. C. Wrist Joint 1. Radiocarpal joint—joint between the radius and proximal carpals ► allows for flexion, extension, adduction, abduction, and circumduction 2. Intercarpal joint—joint between the proximal and distal rows or carpals ► allows for gliding movement

  43. Ulna Radius radiocarpal Intercarpal I V II III IV Thumb Right wrist, anterior (palmar) view

  44. D. Hip joint ► A ball-and-socket structure ► Head of femur articulates with acetabulum ► Stability from acetabulum and capsular ligaments ► Muscle tendons contribute somewhat to stability

  45. Acetabularlabrum Synovial membrane ligamentum teres Headof femur Articularcapsule (cut) Photo of the interior of the hip joint, lateral view

  46. E. Knee joint ► Acts primarily as a hinge joint ► Two fibrocartilage menisci occur within the joint cavity ► Femoropatellar joint—shares the joint cavity

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