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All joints are trade-off between mobility and stability

All joints are trade-off between mobility and stability. Figure 9.1 . Factors that influence mobility and stability of a joint. Articulating surface and surrounding bones Joint capsule and ligaments Muscles that cross joint or are near joint.

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All joints are trade-off between mobility and stability

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  1. All joints are trade-off between mobility and stability Figure 9.1

  2. Factors that influence mobility and stability of a joint • Articulating surface and surrounding bones • Joint capsule and ligaments • Muscles that cross joint or are near joint

  3. Factors that influence mobility and stability of a joint • Articulating surface and surrounding bones • Determines types of movements possible • Bone-hitting-bone can limit movements • Joint capsule and ligaments • Can restrict or permit movements • Muscle that crosses joint or is near joint • Can stabilize joints • Can limit movement • E.g., hip and knee flex more passively than actively

  4. Shoulder (glenohumoral) joint • shallow ball and socket • Very mobile with poor stability • Loose joint capsule (particularly anteriorly) and lacks well developed ligaments • Promotes mobility, lacks stability • Stabilized largely by muscles (rotator cuff) • Small rotator cuff muscles • Small muscles + big forces = easy injury • Other muscles crossing joint • E.g., Tendon of long head of biceps also stabilizes

  5. Figure 9.15

  6. Figure 9.15 continued

  7. Hip/coxal Joint (acetabulofemoral) • Deep ball and socket • Very stable with decent mobility (but significantly less than shoulder) • Thick joint capsule with well developed ligaments • Creates stability • Large muscles stabilize joint • Stabilizes, but may mildly limits mobility

  8. Ball and socket shape allows many types of movement

  9. Deep socket • Acetabular labrum (fibrocartilage), enhances depth • increases stability, but reduces mobility • Movement stops when “bone hits bone” labrum

  10. Thick, complete joint capsule • 3 well developed ligaments • Stabilize the joint, limit movement

  11. Knee joint • “modified hinge joint” • Little stability from articulating surfaces • Joint capsule & Complex set of ligaments • Large muscles cross joint Primary stabilizers Limit mobility

  12. Hinge joint • Primarily flexion and extension • Articulating surfaces do not support one another

  13. Menisci • Improve fit • Stabilizes joint • Distributes weight/force

  14. Joint capsule • Loose, slack anteriorly • Permits flexion • Thick and tight posteriorly • Prevents, “brake to” extension

  15. Collateral (tibial & fibular) ligaments • On medial and lateral joint surfaces • Prevent side-to-side (medial-lateral) displacement

  16. Collateral (tibial & fibular) ligaments

  17. Cruciate Ligaments • Allow flexion and extension • Prevents anterior and posterior displacement of tibia

  18. Cruciate ligaments prevents prevents Posterior cruciate Why not located on anterior and posterior surfaces? Anterior cruciate

  19. Muscles vm vl • Quadriceps femoris group • Petallapetallar ligament • Hamstrings • Gastrocnemius • popliteus

  20. Figure 9.5

  21. Figure 9.19

  22. Page 278_01

  23. Figure 9.19 continued

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